Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.
In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Any method used for determining the location of and relative distances between genes on a chromosome.
Mapping of the KARYOTYPE of a cell.
Staining of bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes. Applications include the determination of chromosome rearrangements in malformation syndromes and cancer, the chemistry of chromosome segments, chromosome changes during evolution, and, in conjunction with cell hybridization studies, chromosome mapping.
An exchange of segments between the sister chromatids of a chromosome, either between the sister chromatids of a meiotic tetrad or between the sister chromatids of a duplicated somatic chromosome. Its frequency is increased by ultraviolet and ionizing radiation and other mutagenic agents and is particularly high in BLOOM SYNDROME.
Abnormal number or structure of the SEX CHROMOSOMES. Some sex chromosome aberrations are associated with SEX CHROMOSOME DISORDERS and SEX CHROMOSOME DISORDERS OF SEX DEVELOPMENT.
A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.
Very long DNA molecules and associated proteins, HISTONES, and non-histone chromosomal proteins (CHROMOSOMAL PROTEINS, NON-HISTONE). Normally 46 chromosomes, including two sex chromosomes are found in the nucleus of human cells. They carry the hereditary information of the individual.
A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.
The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.
Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from Thompson et al., Genetics in Medicine, 5th ed, p429)
Induction and quantitative measurement of chromosomal damage leading to the formation of micronuclei (MICRONUCLEI, CHROMOSOME-DEFECTIVE) in cells which have been exposed to genotoxic agents or IONIZING RADIATION.
Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.
A technique for visualizing CHROMOSOME ABERRATIONS using fluorescently labeled DNA probes which are hybridized to chromosomal DNA. Multiple fluorochromes may be attached to the probes. Upon hybridization, this produces a multicolored, or painted, effect with a unique color at each site of hybridization. This technique may also be used to identify cross-species homology by labeling probes from one species for hybridization with chromosomes from another species.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.
Warfare involving the use of NUCLEAR WEAPONS.
Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.
Actual loss of portion of a chromosome.
A subdiscipline of genetics which deals with the cytological and molecular analysis of the CHROMOSOMES, and location of the GENES on chromosomes, and the movements of chromosomes during the CELL CYCLE.
A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.
Examination of CHROMOSOMES to diagnose, classify, screen for, or manage genetic diseases and abnormalities. Following preparation of the sample, KARYOTYPING is performed and/or the specific chromosomes are analyzed.
The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).
A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.
Americium. A completely man-made radioactive actinide with atomic symbol Am, atomic number 95, and atomic weight 243. Its valence can range from +3 to +6. Because of its nonmagnetic ground state, it is an excellent superconductor. It is also used in bone mineral analysis and as a radiation source for radiotherapy.
White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.
A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.
The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.
A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.
Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.
A specific pair of GROUP B CHROMOSOMES of the human chromosome classification.
A subdiscipline of genetics that studies RADIATION EFFECTS on the components and processes of biological inheritance.
A specific pair GROUP C CHROMSOMES of the human chromosome classification.
Toxic alkylating agent used in industry; also as antineoplastic and research tool to produce chromosome aberrations and cancers.
A specific pair of GROUP C CHROMSOMES of the human chromosome classification.
The phase of cell nucleus division following PROMETAPHASE, in which the CHROMOSOMES line up across the equatorial plane of the SPINDLE APPARATUS prior to separation.
A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.
Rate of energy dissipation along the path of charged particles. In radiobiology and health physics, exposure is measured in kiloelectron volts per micrometer of tissue (keV/micrometer T).
Defective nuclei produced during the TELOPHASE of MITOSIS or MEIOSIS by lagging CHROMOSOMES or chromosome fragments derived from spontaneous or experimentally induced chromosomal structural changes.
A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.
Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.
The medium-sized, submetacentric human chromosomes, called group C in the human chromosome classification. This group consists of chromosome pairs 6, 7, 8, 9, 10, 11, and 12 and the X chromosome.
Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell.
A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.
A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.
Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of MAMMALS.
The alignment of CHROMOSOMES at homologous sequences.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
A specific pair of GROUP F CHROMOSOMES of the human chromosome classification.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
DNA constructs that are composed of, at least, a REPLICATION ORIGIN, for successful replication, propagation to and maintenance as an extra chromosome in bacteria. In addition, they can carry large amounts (about 200 kilobases) of other sequence for a variety of bioengineering purposes.
The possession of a third chromosome of any one type in an otherwise diploid cell.
One of the two pairs of human chromosomes in the group B class (CHROMOSOMES, HUMAN, 4-5).
The human male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans.
Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.
An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.
The large, metacentric human chromosomes, called group A in the human chromosome classification. This group consists of chromosome pairs 1, 2, and 3.
The human female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in humans.
Either of the two longitudinally adjacent threads formed when a eukaryotic chromosome replicates prior to mitosis. The chromatids are held together at the centromere. Sister chromatids are derived from the same chromosome. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.
A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.
Radiation from sources other than the source of interest. It is due to cosmic rays and natural radioactivity in the environment.
A specific pair of GROUP F CHROMOSOMES of the human chromosome classification.
PHENOTHIAZINES with an amino group at the 3-position that are green crystals or powder. They are used as biological stains.
Uncontrolled release of radioactive material from its containment. This either threatens to, or does, cause exposure to a radioactive hazard. Such an incident may occur accidentally or deliberately.
A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.
Derivatives and polymers of styrene. They are used in the manufacturing of synthetic rubber, plastics, and resins. Some of the polymers form the skeletal structures for ion exchange resin beads.
The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.
A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.
An expression of the number of mitoses found in a stated number of cells.
The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Positively charged particles composed of two protons and two NEUTRONS, i.e. equivalent to HELIUM nuclei, which are emitted during disintegration of heavy ISOTOPES. Alpha rays have very strong ionizing power, but weak penetrability.
The short, submetacentric human chromosomes, called group E in the human chromosome classification. This group consists of chromosome pairs 16, 17, and 18.
A chemosterilant agent that is anticipated to be a carcinogen.
A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.
Penetrating, high-energy electromagnetic radiation emitted from atomic nuclei during NUCLEAR DECAY. The range of wavelengths of emitted radiation is between 0.1 - 100 pm which overlaps the shorter, more energetic hard X-RAYS wavelengths. The distinction between gamma rays and X-rays is based on their radiation source.
I'm sorry for any confusion, but "Kazakhstan" is not a medical term and does not have a medical definition; it is the name of a country located in Central Asia, known officially as the Republic of Kazakhstan.
Chromosomes in which fragments of exogenous DNA ranging in length up to several hundred kilobase pairs have been cloned into yeast through ligation to vector sequences. These artificial chromosomes are used extensively in molecular biology for the construction of comprehensive genomic libraries of higher organisms.
The ratio of radiation dosages required to produce identical change based on a formula comparing other types of radiation with that of gamma or roentgen rays.
The medium-sized, acrocentric human chromosomes, called group D in the human chromosome classification. This group consists of chromosome pairs 13, 14, and 15.
Metacentric chromosomes produced during MEIOSIS or MITOSIS when the CENTROMERE splits transversely instead of longitudinally. The chromosomes produced by this abnormal division are one chromosome having the two long arms of the original chromosome, but no short arms, and the other chromosome consisting of the two short arms and no long arms. Each of these isochromosomes constitutes a simultaneous duplication and deletion.
An ancient country in western Asia, by the twentieth century divided among the former USSR, Turkey, and Iran. It was attacked at various times from before the 7th century B.C. to 69 B.C. by Assyrians, Medes, Persians, the Greeks under Alexander, and the Romans. It changed hands frequently in wars between Neo-Persian and Roman Empires from the 3d to 7th centuries and later under Arabs, Seljuks, Byzantines, and Mongols. In the 19th century Armenian nationalism arose but suffered during Russo-Turkish hostilities. It became part of the Soviet Republic in 1921, with part remaining under Turkey. (Webster's New Geographical Dictionary, 1988)
Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)
The co-inheritance of two or more non-allelic GENES due to their being located more or less closely on the same CHROMOSOME.
The short, acrocentric human chromosomes, called group G in the human chromosome classification. This group consists of chromosome pairs 21 and 22 and the Y chromosome.
An aberration in which a chromosomal segment is deleted and reinserted in the same place but turned 180 degrees from its original orientation, so that the gene sequence for the segment is reversed with respect to that of the rest of the chromosome.
The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
Harmful effects of non-experimental exposure to ionizing or non-ionizing radiation in VERTEBRATES.
The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv).
Aberrant chromosomes with no ends, i.e., circular.
The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.
A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.
The large, submetacentric human chromosomes, called group B in the human chromosome classification. This group consists of chromosome pairs 4 and 5.
A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.
ELECTROMAGNETIC RADIATION or particle radiation (high energy ELEMENTARY PARTICLES) capable of directly or indirectly producing IONS in its passage through matter. The wavelengths of ionizing electromagnetic radiation are equal to or smaller than those of short (far) ultraviolet radiation and include gamma and X-rays.
The mechanisms of eukaryotic CELLS that place or keep the CHROMOSOMES in a particular SUBNUCLEAR SPACE.
Unstable isotopes of cobalt that decay or disintegrate emitting radiation. Co atoms with atomic weights of 54-64, except 59, are radioactive cobalt isotopes.
Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.
The degree of replication of the chromosome set in the karyotype.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.
A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
An agent thought to have disinfectant properties and used as an expectorant. (From Martindale, The Extra Pharmacopoeia, 30th ed, p747)
The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.
Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard X-rays are the higher energy, shorter wavelength X-rays. Soft x-rays or Grenz rays are less energetic and longer in wavelength. The short wavelength end of the X-ray spectrum overlaps the GAMMA RAYS wavelength range. The distinction between gamma rays and X-rays is based on their radiation source.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
The reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule which contained damaged regions. The major repair mechanisms are excision repair, in which defective regions in one strand are excised and resynthesized using the complementary base pairing information in the intact strand; photoreactivation repair, in which the lethal and mutagenic effects of ultraviolet light are eliminated; and post-replication repair, in which the primary lesions are not repaired, but the gaps in one daughter duplex are filled in by incorporation of portions of the other (undamaged) daughter duplex. Excision repair and post-replication repair are sometimes referred to as "dark repair" because they do not require light.
The chromosomal constitution of a cell containing multiples of the normal number of CHROMOSOMES; includes triploidy (symbol: 3N), tetraploidy (symbol: 4N), etc.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
The clear constricted portion of the chromosome at which the chromatids are joined and by which the chromosome is attached to the spindle during cell division.
A condition caused by a brief whole body exposure to more than one sievert dose equivalent of radiation. Acute radiation syndrome is initially characterized by ANOREXIA; NAUSEA; VOMITING; but can progress to hematological, gastrointestinal, neurological, pulmonary, and other major organ dysfunction.
Refraction of LIGHT effected by the media of the EYE.
Unstable isotopes of cesium that decay or disintegrate emitting radiation. Cs atoms with atomic weights of 123, 125-132, and 134-145 are radioactive cesium isotopes.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
The ability of some cells or tissues to survive lethal doses of IONIZING RADIATION. Tolerance depends on the species, cell type, and physical and chemical variables, including RADIATION-PROTECTIVE AGENTS and RADIATION-SENSITIZING AGENTS.
A dosage compensation process occurring at an early embryonic stage in mammalian development whereby, at random, one X CHROMOSOME of the pair is repressed in the somatic cells of females.
Toxic, volatile, flammable liquid hydrocarbon byproduct of coal distillation. It is used as an industrial solvent in paints, varnishes, lacquer thinners, gasoline, etc. Benzene causes central nervous system damage acutely and bone marrow damage chronically and is carcinogenic. It was formerly used as parasiticide.
An alkaloid isolated from Colchicum autumnale L. and used as an antineoplastic.
A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.
Agents that reduce the frequency or rate of spontaneous or induced mutations independently of the mechanism involved.
Chemicals especially for use on instruments to destroy pathogenic organisms. (Boucher, Clinical Dental Terminology, 4th ed)
The short, metacentric human chromosomes, called group F in the human chromosome classification. This group consists of chromosome pairs 19 and 20.
Uranium. A radioactive element of the actinide series of metals. It has an atomic symbol U, atomic number 92, and atomic weight 238.03. U-235 is used as the fissionable fuel in nuclear weapons and as fuel in nuclear power reactors.
Structures within the CELL NUCLEUS of insect cells containing DNA.
The process by which a DNA molecule is duplicated.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.
Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.
Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.
The number of copies of a given gene present in the cell of an organism. An increase in gene dosage (by GENE DUPLICATION for example) can result in higher levels of gene product formation. GENE DOSAGE COMPENSATION mechanisms result in adjustments to the level GENE EXPRESSION when there are changes or differences in gene dosage.
An increased tendency of the GENOME to acquire MUTATIONS when various processes involved in maintaining and replicating the genome are dysfunctional.
DNA present in neoplastic tissue.
Structures which are contained in or part of CHROMOSOMES.
An antineoplastic antibiotic produced by Streptomyces caespitosus. It is one of the bi- or tri-functional ALKYLATING AGENTS causing cross-linking of DNA and inhibition of DNA synthesis.
Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.
The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.
Established cell cultures that have the potential to propagate indefinitely.
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.
A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.
Chemicals that kill or inhibit the growth of fungi in agricultural applications, on wood, plastics, or other materials, in swimming pools, etc.
A variety of simple repeat sequences that are distributed throughout the GENOME. They are characterized by a short repeat unit of 2-8 basepairs that is repeated up to 100 times. They are also known as short tandem repeats (STRs).
The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes.
Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.
The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells.
A method for comparing two sets of chromosomal DNA by analyzing differences in the copy number and location of specific sequences. It is used to look for large sequence changes such as deletions, duplications, amplifications, or translocations.
The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.
Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.
A species of fruit fly much used in genetics because of the large size of its chromosomes.
Form of leukemia characterized by an uncontrolled proliferation of the myeloid lineage and their precursors (MYELOID PROGENITOR CELLS) in the bone marrow and other sites.
The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.
The total relative probability, expressed on a logarithmic scale, that a linkage relationship exists among selected loci. Lod is an acronym for "logarithmic odds."
Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.
Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.
The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)
The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.
Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)
Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
Cell changes manifested by escape from control mechanisms, increased growth potential, alterations in the cell surface, karyotypic abnormalities, morphological and biochemical deviations from the norm, and other attributes conferring the ability to invade, metastasize, and kill.
Susceptibility of chromosomes to breakage leading to translocation; CHROMOSOME INVERSION; SEQUENCE DELETION; or other CHROMOSOME BREAKAGE related aberrations.
The full set of CHROMOSOMES presented as a systematized array of METAPHASE chromosomes from a photomicrograph of a single CELL NUCLEUS arranged in pairs in descending order of size and according to the position of the CENTROMERE. (From Stedman, 25th ed)
Chemicals used to destroy pests of any sort. The concept includes fungicides (FUNGICIDES, INDUSTRIAL); INSECTICIDES; RODENTICIDES; etc.
The complete genetic complement contained in the DNA of a set of CHROMOSOMES in a HUMAN. The length of the human genome is about 3 billion base pairs.
An autosomal recessive inherited disorder characterized by choreoathetosis beginning in childhood, progressive CEREBELLAR ATAXIA; TELANGIECTASIS of CONJUNCTIVA and SKIN; DYSARTHRIA; B- and T-cell immunodeficiency, and RADIOSENSITIVITY to IONIZING RADIATION. Affected individuals are prone to recurrent sinobronchopulmonary infections, lymphoreticular neoplasms, and other malignancies. Serum ALPHA-FETOPROTEINS are usually elevated. (Menkes, Textbook of Child Neurology, 5th ed, p688) The gene for this disorder (ATM) encodes a cell cycle checkpoint protein kinase and has been mapped to chromosome 11 (11q22-q23).
The failure of homologous CHROMOSOMES or CHROMATIDS to segregate during MITOSIS or MEIOSIS with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none.
The condition in which one chromosome of a pair is missing. In a normally diploid cell it is represented symbolically as 2N-1.
An aberration in which an extra chromosome or a chromosomal segment is made.
The loss of one allele at a specific locus, caused by a deletion mutation; or loss of a chromosome from a chromosome pair, resulting in abnormal HEMIZYGOSITY. It is detected when heterozygous markers for a locus appear monomorphic because one of the ALLELES was deleted.
A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.
The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.
The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.
Expulsion of the product of FERTILIZATION before completing the term of GESTATION and without deliberate interference.
Elements of limited time intervals, contributing to particular results or situations.
The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS.
In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
The aperture in the iris through which light passes.
New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.
The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.
DNA constructs that are composed of, at least, all elements, such as a REPLICATION ORIGIN; TELOMERE; and CENTROMERE, required for successful replication, propagation to and maintainance in progeny human cells. In addition, they are constructed to carry other sequences for analysis or gene transfer.
Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle.
A microtubule structure that forms during CELL DIVISION. It consists of two SPINDLE POLES, and sets of MICROTUBULES that may include the astral microtubules, the polar microtubules, and the kinetochore microtubules.
A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
An assisted fertilization technique consisting of the microinjection of a single viable sperm into an extracted ovum. It is used principally to overcome low sperm count, low sperm motility, inability of sperm to penetrate the egg, or other conditions related to male infertility (INFERTILITY, MALE).
An assisted reproductive technique that includes the direct handling and manipulation of oocytes and sperm to achieve fertilization in vitro.
A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.
Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.
A technique with which an unknown region of a chromosome can be explored. It is generally used to isolate a locus of interest for which no probe is available but that is known to be linked to a gene which has been identified and cloned. A fragment containing a known gene is selected and used as a probe to identify other overlapping fragments which contain the same gene. The nucleotide sequences of these fragments can then be characterized. This process continues for the length of the chromosome.
'Abnormalities, Multiple' is a broad term referring to the presence of two or more structural or functional anomalies in an individual, which may be genetic or environmental in origin, and can affect various systems and organs of the body.
A selective increase in the number of copies of a gene coding for a specific protein without a proportional increase in other genes. It occurs naturally via the excision of a copy of the repeating sequence from the chromosome and its extrachromosomal replication in a plasmid, or via the production of an RNA transcript of the entire repeating sequence of ribosomal RNA followed by the reverse transcription of the molecule to produce an additional copy of the original DNA sequence. Laboratory techniques have been introduced for inducing disproportional replication by unequal crossing over, uptake of DNA from lysed cells, or generation of extrachromosomal sequences from rolling circle replication.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.
A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.
The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.

Classification of human colorectal adenocarcinoma cell lines. (1/6775)

Eleven human colorectal adenocarcinoma cell lines established in this laboratory were classified into three groups based on morphological features (light and electron microscopy), modal chromosome number, and ability to synthesize carcinoembryonic antigen (CEA). Group 1 cell lines contained both dedifferentiated and differentiating cells growing in tight clusters or islands of epithelium-like cells; their modal chromosome number was about 47, and they synthesized small to moderate amounts of CEA. Group 2 cell lines were more dedifferentiated, were hyperdiploid, and synthesized small amounts of CEA. Group 3 cell lines were morphologically similar to those of Group 1 by light microscopy. They differed ultrastructurally by containing microvesicular bodies; the modal chromosome number varied from hyperdiploid to hypertriploid or they had bimodal populations of hypodiploid and hypertriploid cells, and they synthesized relatively large amounts of CEA. No correlation could be found between Broder's grade or Duke's classification of the original tumor and modal chromosome number or ability to synthesize CEA. These findings support Nowell's hypothesis that the stem line is different for each solid tumor, which makes it difficult to relate chromosomal changes to the initiation of the neoplastic state.  (+info)

Assaying potential carcinogens with Drosophila. (2/6775)

Drosophila offers many advantages for the detection of mutagenic activity of carcinogenic agents. It provides the quickest assay system for detecting mutations in animals today. Its generation time is short, and Drosophila is cheap and easy to breed in large numbers. The simple genetic testing methods give unequivocal answers about the whole spectrum of relevant genetic damage. A comparison of the detection capacity of assays sampling different kinds of genetic damage revealed that various substances are highly effective in inducing mutations but do not produce chromosome breakage effects at all, or only at much higher concentrations than those required for mutation induction. Of the different assay systems available, the classical sex-linked recessive lethal test deserves priority, in view of its superior capacity to detect mutagens. Of practical importance is also its high sensitivity, because a large number of loci in one fifth of the genome is tested for newly induced forward mutations, including small deletions. The recent findings that Drosophila is capable of carrying out the same metabolic activation reactions as the mammalian liver makes the organism eminently suitable for verifying results obtained in prescreening with fast microbial assay systems. An additional advantage in this respect is the capacity of Drosophila for detecting short-lived activation products, because intracellular metabolic activation appears to occur within the spermatids and spermatocytes.  (+info)

Superimposed histologic and genetic mapping of chromosome 9 in progression of human urinary bladder neoplasia: implications for a genetic model of multistep urothelial carcinogenesis and early detection of urinary bladder cancer. (3/6775)

The evolution of alterations on chromosome 9, including the putative tumor suppressor genes mapped to the 9p21-22 region (the MTS genes), was studied in relation to the progression of human urinary bladder neoplasia by using whole organ superimposed histologic and genetic mapping in cystectomy specimens and was verified in urinary bladder tumors of various pathogenetic subsets with longterm follow-up. The applicability of chromosome 9 allelic losses as non-invasive markers of urothelial neoplasia was tested on voided urine and/or bladder washings of patients with urinary bladder cancer. Although sequential multiple hits in the MTS locus were documented in the development of intraurothelial precursor lesions, the MTS genes do not seem to represent a major target for p21-23 deletions in bladder cancer. Two additional tumor suppressor genes involved in bladder neoplasia located distally and proximally to the MTS locus within p22-23 and p11-13 regions respectively were identified. Several distinct putative tumor suppressor gene loci within the q12-13, q21-22, and q34 regions were identified on the q arm. In particular, the pericentromeric q12-13 area may contain the critical tumor suppressor gene or genes for the development of early urothelial neoplasia. Allelic losses of chromosome 9 were associated with expansion of the abnormal urothelial clone which frequently involved large areas of urinary bladder mucosa. These losses could be found in a high proportion of urothelial tumors and in voided urine or bladder washing samples of nearly all patients with urinary bladder carcinoma.  (+info)

Comparative molecular genetic profiles of anaplastic astrocytomas/glioblastomas multiforme and their subsequent recurrences. (4/6775)

Malignant glial tumors (anaplastic astrocytomas and glioblastomas multiforme) arise mostly either from the progression of low grade precursor lesions or rapidly in a de novo fashion and contain distinct genetic alterations. There is, however, a third subset of malignant gliomas in which genetic lesions remain to be identified. Following surgical resection, all gliomas appear to have an inherent tendency to recur. Comparative molecular analysis of ten primary malignant gliomas (three anaplastic astrocytomas and seven glioblastomas multiforme) with their recurrences identified two distinct subgroups of recurrent tumors. In one group, primary tumors harbored genetic aberrations frequently associated with linear progression or de novo formation pathways of glial tumorigenesis and maintained their genetic profiles upon recurrence. In the other subset with no detectable known genetic mutations at first presentation, the recurrent tumors sustained specific abnormalities associated with pathways of linear progression or de novo formation. These included loss of genes on chromosomes 17 and 10, mutations in the p53 gene, homozygous deletion of the DMBTA1 and p16 and/ or p15 genes and amplification and/or overexpression of CDK4 and alpha form of the PDGF receptor. Recurrent tumors from both groups also displayed an abnormal expression profile of the metalloproteinase, gel A, and its inhibitor, TIMP-2, consistent with their highly invasive behavior. Delineation of the molecular differences between malignant glioblastomas and their subsequent recurrences may have important implications for the development of rational clinical approaches for this neoplasm that remains refractory to existing therapeutic modalities.  (+info)

Specific chromosomal aberrations and amplification of the AIB1 nuclear receptor coactivator gene in pancreatic carcinomas. (5/6775)

To screen pancreatic carcinomas for chromosomal aberrations we have applied molecular cytogenetic techniques, including fluorescent in situ hybridization, comparative genomic hybridization, and spectral karyotyping to a series of nine established cell lines. Comparative genomic hybridization revealed recurring chromosomal gains on chromosome arms 3q, 5p, 7p, 8q, 12p, and 20q. Chromosome losses were mapped to chromosome arms 8p, 9p, 17p, 18q, 19p, and chromosome 21. The comparison with comparative genomic hybridization data from primary pancreatic tumors indicates that a specific pattern of chromosomal copy number changes is maintained in cell culture. Metaphase chromosomes from six cell lines were analyzed by spectral karyotyping, a technique that allows one to visualize all chromosomes simultaneously in different colors. Spectral karyotyping identified multiple chromosomal rearrangements, the majority of which were unbalanced. No recurring reciprocal translocation was detected. Cytogenetic aberrations were confirmed using fluorescent in situ hybridization with probes for the MDR gene and the tumor suppressor genes p16 and DCC. Copy number increases on chromosome 20q were validated with a probe specific for the nuclear receptor coactivator AIB1 that maps to chromosome 20q12. Amplification of this gene was identified in six of nine pancreatic cancer cell lines and correlated with increased expression.  (+info)

Conserved mechanism of PLAG1 activation in salivary gland tumors with and without chromosome 8q12 abnormalities: identification of SII as a new fusion partner gene. (6/6775)

We have previously shown (K. Kas et al, Nat. Genet., 15: 170-174, 1997) that the developmentally regulated zinc finger gene pleomorphic adenoma gene 1 (PLAG1) is the target gene in 8q12 in pleomorphic adenomas of the salivary glands with t(3;8)(p21;q12) translocations. The t(3;8) results in promoter swapping between PLAG1 and the constitutively expressed gene for beta-catenin (CTNNB1), leading to activation of PLAG1 expression and reduced expression of CTNNB1. Here we have studied the expression of PLAG1 by Northern blot analysis in 47 primary benign and malignant human tumors with or without cytogenetic abnormalities of 8q12. Overexpression of PLAG1 was found in 23 tumors (49%). Thirteen of 17 pleomorphic adenomas with a normal karyotype and 5 of 10 with 12q13-15 abnormalities overexpressed PLAG1, which demonstrates that PLAG1 activation is a frequent event in adenomas irrespective of karyotype. In contrast, PLAG1 was overexpressed in only 2 of 11 malignant salivary gland tumors analyzed, which suggests that, at least in salivary gland tumors, PLAG1 activation preferentially occurs in benign tumors. PLAG1 over-expression was also found in three of nine mesenchymal tumors, i.e., in two uterine leiomyomas and one leiomyosarcoma. RNase protection, rapid amplification of 5'-cDNA ends (5'-RACE), and reverse transcription-PCR analyses of five adenomas with a normal karyotype revealed fusion transcripts in three tumors. Nucleotide sequence analysis of these showed that they contained fusions between PLAG1 and CTNNB1 (one case) or PLAG1 and a novel fusion partner gene, i.e., the gene encoding the transcription elongation factor SII (two cases). The fusions occurred in the 5' noncoding region of PLAG1, leading to exchange of regulatory control elements and, as a consequence, activation of PLAG1 gene expression. Because all of the cases had grossly normal karyotypes, the rearrangements must result from cryptic rearrangements. The results suggest that in addition to chromosomal translocations and cryptic rearrangements, PLAG1 may also be activated by mutations or indirect mechanisms. Our findings establish a conserved mechanism of PLAG1 activation in salivary gland tumors with and without 8q12 aberrations, which indicates that such activation is a frequent event in these tumors.  (+info)

Partial monosomy and partial trisomy 18 in two offspring of carrier of pericentric inversion of chromosome 18. (7/6775)

A pericentric inversion of chromosome 18 is described in the mother of a patient with clinical diagnosis of 18q--syndrome. The propositus' chromosome complement includes the recombinant 18 with deficiency of the distal one-third of the long arm and duplication of the terminal segment of the short arm. The propositus' sister carrier the recombinant 18 with a duplication of the distal one-third of the long arm and a deficiency of the terminal segment of the short arm. The relative length of the inverted segment represents about 60% of the total chromosome 18 length. The probability of recombinant formation following the occurrence of a chiasma within the inverted segment is predicted to be high.  (+info)

Structure and inheritance of some heterozygous Robertsonian translocation in man. (8/6775)

Banding studies in 25 Robertsonian translocations showed that all could be interpreted as stable dicentrics. The mechanism for their stability is likely to be the proximity of their centromeres but centromeric suppression could also have a role. In many of these dicentric translocations, discontinuous centromeric suppression, as indicated by chromatid separation at one of the centromeric regions, was observed in C-banded preparations. A further observation of undefined relation to the first was that the ratio of the two constitutive centromeric heterochromatin (CCH) regions from the component chromosomes of the translocations was variable in the same translocation type, e.g. t(13;14). It is proposed that this ratio may influence the segregation ratio. Abnormal spermatogenesis is suggested as the likely mechanism for the difference in the proportion of aneuploid offspring in the progeny of maternal and paternal heterozygotes. Neither of the t dic(21;21)s could be interpreted as isochromosomes. It is proposed that Robertsonian fusion translocations be defined as stable, dicentric, whole-arm translocations, with both centromeres in a median position and resulting in the loss of a small acentric fragment during this formation. It is suggested that they occur at high frequency between telocentric or, as in man, certain acrocentric chromosomes because of some intrinsic property of those chromosomes not possessed by metacentric chromosomes and mediated by interphase association of centromeres.  (+info)

Chromosome aberrations refer to structural and numerical changes in the chromosomes that can occur spontaneously or as a result of exposure to mutagenic agents. These changes can affect the genetic material encoded in the chromosomes, leading to various consequences such as developmental abnormalities, cancer, or infertility.

Structural aberrations include deletions, duplications, inversions, translocations, and rings, which result from breaks and rearrangements of chromosome segments. Numerical aberrations involve changes in the number of chromosomes, such as aneuploidy (extra or missing chromosomes) or polyploidy (multiples of a complete set of chromosomes).

Chromosome aberrations can be detected and analyzed using various cytogenetic techniques, including karyotyping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). These methods allow for the identification and characterization of chromosomal changes at the molecular level, providing valuable information for genetic counseling, diagnosis, and research.

Chromosomes are thread-like structures that exist in the nucleus of cells, carrying genetic information in the form of genes. They are composed of DNA and proteins, and are typically present in pairs in the nucleus, with one set inherited from each parent. In humans, there are 23 pairs of chromosomes for a total of 46 chromosomes. Chromosomes come in different shapes and forms, including sex chromosomes (X and Y) that determine the biological sex of an individual. Changes or abnormalities in the number or structure of chromosomes can lead to genetic disorders and diseases.

Chromosome mapping, also known as physical mapping, is the process of determining the location and order of specific genes or genetic markers on a chromosome. This is typically done by using various laboratory techniques to identify landmarks along the chromosome, such as restriction enzyme cutting sites or patterns of DNA sequence repeats. The resulting map provides important information about the organization and structure of the genome, and can be used for a variety of purposes, including identifying the location of genes associated with genetic diseases, studying evolutionary relationships between organisms, and developing genetic markers for use in breeding or forensic applications.

Karyotyping is a medical laboratory test used to study the chromosomes in a cell. It involves obtaining a sample of cells from a patient, usually from blood or bone marrow, and then staining the chromosomes so they can be easily seen under a microscope. The chromosomes are then arranged in pairs based on their size, shape, and other features to create a karyotype. This visual representation allows for the identification and analysis of any chromosomal abnormalities, such as extra or missing chromosomes, or structural changes like translocations or inversions. These abnormalities can provide important information about genetic disorders, diseases, and developmental problems.

Chromosome banding is a technique used in cytogenetics to identify and describe the physical structure and organization of chromosomes. This method involves staining the chromosomes with specific dyes that bind differently to the DNA and proteins in various regions of the chromosome, resulting in a distinct pattern of light and dark bands when viewed under a microscope.

The most commonly used banding techniques are G-banding (Giemsa banding) and R-banding (reverse banding). In G-banding, the chromosomes are stained with Giemsa dye, which preferentially binds to the AT-rich regions, creating a characteristic banding pattern. The bands are numbered from the centromere (the constriction point where the chromatids join) outwards, with the darker bands (rich in A-T base pairs and histone proteins) labeled as "q" arms and the lighter bands (rich in G-C base pairs and arginine-rich proteins) labeled as "p" arms.

R-banding, on the other hand, uses a different staining procedure that results in a reversed banding pattern compared to G-banding. The darker R-bands correspond to the lighter G-bands, and vice versa. This technique is particularly useful for identifying and analyzing specific regions of chromosomes that may be difficult to visualize with G-banding alone.

Chromosome banding plays a crucial role in diagnosing genetic disorders, identifying chromosomal abnormalities, and studying the structure and function of chromosomes in both clinical and research settings.

Sister chromatid exchange (SCE) is a type of genetic recombination that takes place between two identical sister chromatids during the DNA repair process in meiosis or mitosis. It results in an exchange of genetic material between the two chromatids, creating a new combination of genes on each chromatid. This event is a normal part of cell division and helps to increase genetic variability within a population. However, an increased rate of SCEs can also be indicative of exposure to certain genotoxic agents or conditions that cause DNA damage.

Sex chromosome aberrations refer to structural and numerical abnormalities in the sex chromosomes, which are typically represented as X and Y chromosomes in humans. These aberrations can result in variations in the number of sex chromosomes, such as Klinefelter syndrome (47,XXY), Turner syndrome (45,X), and Jacobs/XYY syndrome (47,XYY). They can also include structural changes, such as deletions, duplications, or translocations of sex chromosome material.

Sex chromosome aberrations may lead to a range of phenotypic effects, including differences in physical characteristics, cognitive development, fertility, and susceptibility to certain health conditions. The manifestation and severity of these impacts can vary widely depending on the specific type and extent of the aberration, as well as individual genetic factors and environmental influences.

It is important to note that while sex chromosome aberrations may pose challenges and require medical management, they do not inherently define or limit a person's potential, identity, or worth. Comprehensive care, support, and education can help individuals with sex chromosome aberrations lead fulfilling lives and reach their full potential.

In situ hybridization, fluorescence (FISH) is a type of molecular cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes through the use of fluorescent probes. This technique allows for the direct visualization of genetic material at a cellular level, making it possible to identify chromosomal abnormalities such as deletions, duplications, translocations, and other rearrangements.

The process involves denaturing the DNA in the sample to separate the double-stranded molecules into single strands, then adding fluorescently labeled probes that are complementary to the target DNA sequence. The probe hybridizes to the complementary sequence in the sample, and the location of the probe is detected by fluorescence microscopy.

FISH has a wide range of applications in both clinical and research settings, including prenatal diagnosis, cancer diagnosis and monitoring, and the study of gene expression and regulation. It is a powerful tool for identifying genetic abnormalities and understanding their role in human disease.

Chromosomes are thread-like structures that contain genetic material, i.e., DNA and proteins, present in the nucleus of human cells. In humans, there are 23 pairs of chromosomes, for a total of 46 chromosomes, in each diploid cell. Twenty-two of these pairs are called autosomal chromosomes, which come in identical pairs and contain genes that determine various traits unrelated to sex.

The last pair is referred to as the sex chromosomes (X and Y), which determines a person's biological sex. Females have two X chromosomes (46, XX), while males possess one X and one Y chromosome (46, XY). Chromosomes vary in size, with the largest being chromosome 1 and the smallest being the Y chromosome.

Human chromosomes are typically visualized during mitosis or meiosis using staining techniques that highlight their banding patterns, allowing for identification of specific regions and genes. Chromosomal abnormalities can lead to various genetic disorders, including Down syndrome (trisomy 21), Turner syndrome (monosomy X), and Klinefelter syndrome (XXY).

Human chromosome pair 1 refers to the first pair of chromosomes in a set of 23 pairs found in the cells of the human body, excluding sex cells (sperm and eggs). Each cell in the human body, except for the gametes, contains 46 chromosomes arranged in 23 pairs. These chromosomes are rod-shaped structures that contain genetic information in the form of DNA.

Chromosome pair 1 is the largest pair, making up about 8% of the total DNA in a cell. Each chromosome in the pair consists of two arms - a shorter p arm and a longer q arm - connected at a centromere. Chromosome 1 carries an estimated 2,000-2,500 genes, which are segments of DNA that contain instructions for making proteins or regulating gene expression.

Defects or mutations in the genes located on chromosome 1 can lead to various genetic disorders and diseases, such as Charcot-Marie-Tooth disease type 1A, Huntington's disease, and certain types of cancer.

The X chromosome is one of the two types of sex-determining chromosomes in humans (the other being the Y chromosome). It's one of the 23 pairs of chromosomes that make up a person's genetic material. Females typically have two copies of the X chromosome (XX), while males usually have one X and one Y chromosome (XY).

The X chromosome contains hundreds of genes that are responsible for the production of various proteins, many of which are essential for normal bodily functions. Some of the critical roles of the X chromosome include:

1. Sex Determination: The presence or absence of the Y chromosome determines whether an individual is male or female. If there is no Y chromosome, the individual will typically develop as a female.
2. Genetic Disorders: Since females have two copies of the X chromosome, they are less likely to be affected by X-linked genetic disorders than males. Males, having only one X chromosome, will express any recessive X-linked traits they inherit.
3. Dosage Compensation: To compensate for the difference in gene dosage between males and females, a process called X-inactivation occurs during female embryonic development. One of the two X chromosomes is randomly inactivated in each cell, resulting in a single functional copy per cell.

The X chromosome plays a crucial role in human genetics and development, contributing to various traits and characteristics, including sex determination and dosage compensation.

Chromosome disorders are a group of genetic conditions caused by abnormalities in the number or structure of chromosomes. Chromosomes are thread-like structures located in the nucleus of cells that contain most of the body's genetic material, which is composed of DNA and proteins. Normally, humans have 23 pairs of chromosomes, for a total of 46 chromosomes.

Chromosome disorders can result from changes in the number of chromosomes (aneuploidy) or structural abnormalities in one or more chromosomes. Some common examples of chromosome disorders include:

1. Down syndrome: a condition caused by an extra copy of chromosome 21, resulting in intellectual disability, developmental delays, and distinctive physical features.
2. Turner syndrome: a condition that affects only females and is caused by the absence of all or part of one X chromosome, resulting in short stature, lack of sexual development, and other symptoms.
3. Klinefelter syndrome: a condition that affects only males and is caused by an extra copy of the X chromosome, resulting in tall stature, infertility, and other symptoms.
4. Cri-du-chat syndrome: a condition caused by a deletion of part of the short arm of chromosome 5, resulting in intellectual disability, developmental delays, and a distinctive cat-like cry.
5. Fragile X syndrome: a condition caused by a mutation in the FMR1 gene on the X chromosome, resulting in intellectual disability, behavioral problems, and physical symptoms.

Chromosome disorders can be diagnosed through various genetic tests, such as karyotyping, chromosomal microarray analysis (CMA), or fluorescence in situ hybridization (FISH). Treatment for these conditions depends on the specific disorder and its associated symptoms and may include medical interventions, therapies, and educational support.

A micronucleus test is a type of genetic toxicology assay used to detect the presence of micronuclei in cells, which are small chromosomal fragments or whole chromosomes that have been missegregated during cell division. The test measures the frequency of micronuclei in cells exposed to a potential genotoxic agent, such as a chemical or radiation, and compares it to the frequency in untreated control cells.

The assay is typically performed on cultured mammalian cells, such as human lymphocytes or Chinese hamster ovary (CHO) cells, and involves exposing the cells to the test agent for a specific period of time, followed by staining and examination of the cells under a microscope. The micronuclei are identified based on their size, shape, and staining characteristics, and the frequency of micronucleated cells is calculated as a measure of genotoxic potential.

Micronucleus tests are widely used in regulatory toxicology to assess the genetic safety of chemicals, drugs, and other substances, and can provide valuable information on potential risks to human health. The test is also used in basic research to study the mechanisms of genotoxicity and chromosomal instability.

Mutagenicity tests are a type of laboratory assays used to identify agents that can cause genetic mutations. These tests detect changes in the DNA of organisms, such as bacteria, yeast, or mammalian cells, after exposure to potential mutagens. The most commonly used mutagenicity test is the Ames test, which uses a strain of Salmonella bacteria that is sensitive to mutagens. If a chemical causes an increase in the number of revertants (reversion to the wild type) in the bacterial population, it is considered to be a mutagen. Other tests include the mouse lymphoma assay and the chromosomal aberration test. These tests are used to evaluate the potential genotoxicity of chemicals and are an important part of the safety evaluation process for new drugs, chemicals, and other substances.

Chromosome painting is a molecular cytogenetic technique used to identify and visualize the specific chromosomes or chromosomal regions that are present in an abnormal location or number in a cell. This technique uses fluorescent probes that bind specifically to different chromosomes or chromosomal regions, allowing for their identification under a fluorescence microscope.

The process of chromosome painting involves labeling different chromosomes or chromosomal regions with fluorescent dyes of distinct colors. The labeled probes are then hybridized to the metaphase chromosomes of a cell, and any excess probe is washed away. The resulting fluorescent pattern allows for the identification of specific chromosomes or chromosomal regions that have been gained, lost, or rearranged in the genome.

Chromosome painting has numerous applications in medical genetics, including prenatal diagnosis, cancer cytogenetics, and constitutional genetic disorders. It can help to identify chromosomal abnormalities such as translocations, deletions, and duplications that may contribute to disease or cancer development.

Human chromosome pair 11 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and together they contain the genetic material that is inherited from both parents. They are located on the eleventh position in the standard karyotype, which is a visual representation of the 23 pairs of human chromosomes.

Chromosome 11 is one of the largest human chromosomes and contains an estimated 135 million base pairs. It contains approximately 1,400 genes that provide instructions for making proteins, as well as many non-coding RNA molecules that play a role in regulating gene expression.

Chromosome 11 is known to contain several important genes and genetic regions associated with various human diseases and conditions. For example, it contains the Wilms' tumor 1 (WT1) gene, which is associated with kidney cancer in children, and the neurofibromatosis type 1 (NF1) gene, which is associated with a genetic disorder that causes benign tumors to grow on nerves throughout the body. Additionally, chromosome 11 contains the region where the ABO blood group genes are located, which determine a person's blood type.

It's worth noting that human chromosomes come in pairs because they contain two copies of each gene, one inherited from the mother and one from the father. This redundancy allows for genetic diversity and provides a backup copy of essential genes, ensuring their proper function and maintaining the stability of the genome.

Human chromosome pair 7 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and together they contain the genetic material that is inherited from both parents. They are identical in size, shape, and banding pattern and are therefore referred to as homologous chromosomes.

Chromosome 7 is one of the autosomal chromosomes, meaning it is not a sex chromosome (X or Y). It is composed of double-stranded DNA that contains approximately 159 million base pairs and around 1,200 genes. Chromosome 7 contains several important genes associated with human health and disease, including those involved in the development of certain types of cancer, such as colon cancer and lung cancer, as well as genetic disorders such as Williams-Beuren syndrome and Charcot-Marie-Tooth disease.

Abnormalities in chromosome 7 have been linked to various genetic conditions, including deletions, duplications, translocations, and other structural changes. These abnormalities can lead to developmental delays, intellectual disabilities, physical abnormalities, and increased risk of certain types of cancer.

Sex chromosomes, often denoted as X and Y, are one of the 23 pairs of human chromosomes found in each cell of the body. Normally, females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY). The sex chromosomes play a significant role in determining the sex of an individual. They contain genes that contribute to physical differences between men and women. Any variations or abnormalities in the number or structure of these chromosomes can lead to various genetic disorders and conditions related to sexual development and reproduction.

Mutagens are physical or chemical agents that can cause permanent changes in the structure of genetic material, including DNA and chromosomes, leading to mutations. These mutations can be passed down to future generations and may increase the risk of cancer and other diseases. Examples of mutagens include ultraviolet (UV) radiation, tobacco smoke, and certain chemicals found in industrial settings. It is important to note that not all mutations are harmful, but some can have negative effects on health and development.

Nuclear warfare is not a medical term per se, but it refers to a military conflict using nuclear weapons. However, the medical and public health communities have studied the potential consequences of nuclear warfare extensively due to its catastrophic health impacts.

In a medical context, a nuclear explosion releases a massive amount of energy in the form of light, heat, and a shockwave, which can cause significant destruction and loss of life from the blast alone. Additionally, the explosion produces radioactive materials that contaminate the environment, leading to both immediate and long-term health effects.

Immediate medical consequences of nuclear warfare include:

1. Blast injuries: The shockwave from a nuclear explosion can cause severe trauma, including fractures, internal injuries, and burns.
2. Radiation exposure: Acute radiation sickness can occur in individuals exposed to high levels of ionizing radiation, leading to symptoms such as nausea, vomiting, diarrhea, fever, and potentially death.
3. Thermal burns: The intense heat generated by a nuclear explosion can cause severe thermal burns, similar to those seen in major fires or explosions.
4. Eye injuries: Flash blindness and retinal burns can occur due to the bright flash of light emitted during the explosion.

Long-term medical consequences of nuclear warfare include:

1. Radiation-induced cancers: Exposure to ionizing radiation increases the risk of developing various types of cancer, such as leukemia and solid tumors, over time.
2. Genetic mutations: Ionizing radiation can cause genetic mutations that may be passed down through generations, potentially leading to birth defects and other health issues.
3. Psychological trauma: The aftermath of a nuclear war would likely result in significant psychological distress, including post-traumatic stress disorder (PTSD), depression, and anxiety.
4. Environmental contamination: Radioactive fallout from a nuclear explosion can contaminate the environment, making large areas uninhabitable for extended periods. This contamination could lead to food and water shortages, further exacerbating health issues.

Preparing for and responding to a nuclear warfare event would require a coordinated effort between medical professionals, emergency responders, and public health officials to minimize the immediate and long-term health impacts on affected populations.

Corneal wavefront aberration is a measurement of the irregularities in the shape and curvature of the cornea, which can affect the way light enters the eye and is focused on the retina. A wavefront aberration test uses a device to measure the refraction of light as it passes through the cornea and calculates the degree of any distortions or irregularities in the wavefront of the light. This information can be used to guide treatment decisions, such as the prescription for eyeglasses or contact lenses, or the planning of a surgical procedure to correct the aberration.

Corneal wavefront aberrations can be classified into two types: low-order and high-order aberrations. Low-order aberrations include myopia (nearsightedness), hyperopia (farsightedness), and astigmatism, which are common refractive errors that can be easily corrected with glasses or contact lenses. High-order aberrations are more complex irregularities in the wavefront of light that cannot be fully corrected with traditional eyeglasses or contact lenses. These may include coma, trefoil, and spherical aberration, among others.

High-order corneal wavefront aberrations can affect visual quality, causing symptoms such as glare, halos around lights, and decreased contrast sensitivity. They are often associated with conditions that cause changes in the shape of the cornea, such as keratoconus or corneal surgery. In some cases, high-order aberrations can be corrected with specialized contact lenses or refractive surgery procedures such as wavefront-guided LASIK or PRK.

A chromosome deletion is a type of genetic abnormality that occurs when a portion of a chromosome is missing or deleted. Chromosomes are thread-like structures located in the nucleus of cells that contain our genetic material, which is organized into genes.

Chromosome deletions can occur spontaneously during the formation of reproductive cells (eggs or sperm) or can be inherited from a parent. They can affect any chromosome and can vary in size, from a small segment to a large portion of the chromosome.

The severity of the symptoms associated with a chromosome deletion depends on the size and location of the deleted segment. In some cases, the deletion may be so small that it does not cause any noticeable symptoms. However, larger deletions can lead to developmental delays, intellectual disabilities, physical abnormalities, and various medical conditions.

Chromosome deletions are typically detected through a genetic test called karyotyping, which involves analyzing the number and structure of an individual's chromosomes. Other more precise tests, such as fluorescence in situ hybridization (FISH) or chromosomal microarray analysis (CMA), may also be used to confirm the diagnosis and identify the specific location and size of the deletion.

Cytogenetics is a branch of genetics that deals with the study of chromosomes and their structure, function, and abnormalities. It involves the examination of chromosome number and structure in the cells of an organism, usually through microscopic analysis of chromosomes prepared from cell cultures or tissue samples. Cytogenetic techniques can be used to identify chromosomal abnormalities associated with genetic disorders, cancer, and other diseases.

The process of cytogenetics typically involves staining the chromosomes to make them visible under a microscope, and then analyzing their number, size, shape, and banding pattern. Chromosomal abnormalities such as deletions, duplications, inversions, translocations, and aneuploidy (abnormal number of chromosomes) can be detected through cytogenetic analysis.

Cytogenetics is an important tool in medical genetics and has many clinical applications, including prenatal diagnosis, cancer diagnosis and monitoring, and identification of genetic disorders. Advances in molecular cytogenetic techniques, such as fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH), have improved the resolution and accuracy of chromosome analysis and expanded its clinical applications.

Translocation, genetic, refers to a type of chromosomal abnormality in which a segment of a chromosome is transferred from one chromosome to another, resulting in an altered genome. This can occur between two non-homologous chromosomes (non-reciprocal translocation) or between two homologous chromosomes (reciprocal translocation). Genetic translocations can lead to various clinical consequences, depending on the genes involved and the location of the translocation. Some translocations may result in no apparent effects, while others can cause developmental abnormalities, cancer, or other genetic disorders. In some cases, translocations can also increase the risk of having offspring with genetic conditions.

Cytogenetic analysis is a laboratory technique used to identify and study the structure and function of chromosomes, which are the structures in the cell that contain genetic material. This type of analysis involves examining the number, size, shape, and banding pattern of chromosomes in cells, typically during metaphase when they are at their most condensed state.

There are several methods used for cytogenetic analysis, including karyotyping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). Karyotyping involves staining the chromosomes with a dye to visualize their banding patterns and then arranging them in pairs based on their size and shape. FISH uses fluorescent probes to label specific DNA sequences, allowing for the detection of genetic abnormalities such as deletions, duplications, or translocations. CGH compares the DNA content of two samples to identify differences in copy number, which can be used to detect chromosomal imbalances.

Cytogenetic analysis is an important tool in medical genetics and is used for a variety of purposes, including prenatal diagnosis, cancer diagnosis and monitoring, and the identification of genetic disorders.

Aneuploidy is a medical term that refers to an abnormal number of chromosomes in a cell. Chromosomes are thread-like structures located inside the nucleus of cells that contain genetic information in the form of genes.

In humans, the normal number of chromosomes in a cell is 46, arranged in 23 pairs. Aneuploidy occurs when there is an extra or missing chromosome in one or more of these pairs. For example, Down syndrome is a condition that results from an extra copy of chromosome 21, also known as trisomy 21.

Aneuploidy can arise during the formation of gametes (sperm or egg cells) due to errors in the process of cell division called meiosis. These errors can result in eggs or sperm with an abnormal number of chromosomes, which can then lead to aneuploidy in the resulting embryo.

Aneuploidy is a significant cause of birth defects and miscarriages. The severity of the condition depends on which chromosomes are affected and the extent of the abnormality. In some cases, aneuploidy may have no noticeable effects, while in others it can lead to serious health problems or developmental delays.

Human chromosome pair 13 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.

Chromosomes carry genetic information in the form of genes, which are sequences of DNA that code for specific traits and functions. Human cells typically have 23 pairs of chromosomes, for a total of 46 chromosomes. Chromosome pair 13 is one of the autosomal pairs, meaning it is not a sex chromosome (X or Y).

Chromosome pair 13 contains several important genes that are associated with various genetic disorders, such as cri-du-chat syndrome and Phelan-McDermid syndrome. Cri-du-chat syndrome is caused by a deletion of the short arm of chromosome 13 (13p), resulting in distinctive cat-like crying sounds in infants, developmental delays, and intellectual disabilities. Phelan-McDermid syndrome is caused by a deletion or mutation of the terminal end of the long arm of chromosome 13 (13q), leading to developmental delays, intellectual disability, absent or delayed speech, and autistic behaviors.

It's important to note that while some genetic disorders are associated with specific chromosomal abnormalities, many factors can contribute to the development and expression of these conditions, including environmental influences and interactions between multiple genes.

Americium (Am-241) is a radioactive metallic element with the symbol "Am" and atomic number 95. It is a member of the actinide series and does not occur naturally, but can be produced in nuclear reactors. Americium-241 is most commonly used as a source of ionizing radiation in smoke detectors.

It is important to note that handling and storing americium requires proper training and equipment due to its radioactive nature. Improper handling or disposal can result in serious health risks, including radiation exposure and contamination.

Lymphocytes are a type of white blood cell that is an essential part of the immune system. They are responsible for recognizing and responding to potentially harmful substances such as viruses, bacteria, and other foreign invaders. There are two main types of lymphocytes: B-lymphocytes (B-cells) and T-lymphocytes (T-cells).

B-lymphocytes produce antibodies, which are proteins that help to neutralize or destroy foreign substances. When a B-cell encounters a foreign substance, it becomes activated and begins to divide and differentiate into plasma cells, which produce and secrete large amounts of antibodies. These antibodies bind to the foreign substance, marking it for destruction by other immune cells.

T-lymphocytes, on the other hand, are involved in cell-mediated immunity. They directly attack and destroy infected cells or cancerous cells. T-cells can also help to regulate the immune response by producing chemical signals that activate or inhibit other immune cells.

Lymphocytes are produced in the bone marrow and mature in either the bone marrow (B-cells) or the thymus gland (T-cells). They circulate throughout the body in the blood and lymphatic system, where they can be found in high concentrations in lymph nodes, the spleen, and other lymphoid organs.

Abnormalities in the number or function of lymphocytes can lead to a variety of immune-related disorders, including immunodeficiency diseases, autoimmune disorders, and cancer.

Human chromosome pair 17 consists of two rod-shaped structures present in the nucleus of each human cell. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex called chromatin. Chromosomes carry genetic information in the form of genes, which are segments of DNA that contain instructions for the development and function of an organism.

Human cells typically have 23 pairs of chromosomes, for a total of 46 chromosomes. Pair 17 is one of the autosomal pairs, meaning it is not a sex chromosome (X or Y). Chromosome 17 is a medium-sized chromosome and contains an estimated 800 million base pairs of DNA. It contains approximately 1,500 genes that provide instructions for making proteins and regulating various cellular processes.

Chromosome 17 is associated with several genetic disorders, including inherited cancer syndromes such as Li-Fraumeni syndrome and hereditary nonpolyposis colorectal cancer (HNPCC). Mutations in genes located on chromosome 17 can increase the risk of developing various types of cancer, including breast, ovarian, colon, and pancreatic cancer.

Chromosome segregation is the process that occurs during cell division (mitosis or meiosis) where replicated chromosomes are separated and distributed equally into two daughter cells. Each chromosome consists of two sister chromatids, which are identical copies of genetic material. During chromosome segregation, these sister chromatids are pulled apart by a structure called the mitotic spindle and moved to opposite poles of the cell. This ensures that each new cell receives one copy of each chromosome, preserving the correct number and composition of chromosomes in the organism.

Chromosome breakage is a medical term that refers to the breaking or fragmentation of chromosomes, which are thread-like structures located in the nucleus of cells that carry genetic information. Normally, chromosomes are tightly coiled and consist of two strands called chromatids, joined together at a central point called the centromere.

Chromosome breakage can occur spontaneously or be caused by environmental factors such as radiation or chemicals, or inherited genetic disorders. When a chromosome breaks, it can result in various genetic abnormalities, depending on the location and severity of the break.

For instance, if the break occurs in a region containing important genes, it can lead to the loss or alteration of those genes, causing genetic diseases or birth defects. In some cases, the broken ends of the chromosome may rejoin incorrectly, leading to chromosomal rearrangements such as translocations, deletions, or inversions. These rearrangements can also result in genetic disorders or cancer.

Chromosome breakage is commonly observed in individuals with certain inherited genetic conditions, such as Bloom syndrome, Fanconi anemia, and ataxia-telangiectasia, which are characterized by an increased susceptibility to chromosome breakage due to defects in DNA repair mechanisms.

Bacterial chromosomes are typically circular, double-stranded DNA molecules that contain the genetic material of bacteria. Unlike eukaryotic cells, which have their DNA housed within a nucleus, bacterial chromosomes are located in the cytoplasm of the cell, often associated with the bacterial nucleoid.

Bacterial chromosomes can vary in size and structure among different species, but they typically contain all of the genetic information necessary for the survival and reproduction of the organism. They may also contain plasmids, which are smaller circular DNA molecules that can carry additional genes and can be transferred between bacteria through a process called conjugation.

One important feature of bacterial chromosomes is their ability to replicate rapidly, allowing bacteria to divide quickly and reproduce in large numbers. The replication of the bacterial chromosome begins at a specific origin point and proceeds in opposite directions until the entire chromosome has been copied. This process is tightly regulated and coordinated with cell division to ensure that each daughter cell receives a complete copy of the genetic material.

Overall, the study of bacterial chromosomes is an important area of research in microbiology, as understanding their structure and function can provide insights into bacterial genetics, evolution, and pathogenesis.

Human chromosome pair 4 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and they are identical or very similar in length and gene content. Chromosomes are made up of DNA, which contains genetic information, and proteins that package and organize the DNA.

Human chromosomes are numbered from 1 to 22, with chromosome pair 4 being one of the autosomal pairs, meaning it is not a sex chromosome (X or Y). Chromosome pair 4 is a medium-sized pair and contains an estimated 1,800-2,000 genes. These genes provide instructions for making proteins that are essential for various functions in the body, such as development, growth, and metabolism.

Abnormalities in chromosome pair 4 can lead to genetic disorders, including Wolf-Hirschhorn syndrome, which is caused by a deletion of part of the short arm of chromosome 4, and 4p16.3 microdeletion syndrome, which is caused by a deletion of a specific region on the short arm of chromosome 4. These conditions can result in developmental delays, intellectual disability, physical abnormalities, and other health problems.

Radiation genetics is a field of study that focuses on the effects of ionizing radiation on genetic material, including DNA and chromosomes. It examines how exposure to radiation can cause mutations in genes and chromosomes, which can then be passed down from one generation to the next. This field of study is important for understanding the potential health risks associated with exposure to ionizing radiation, such as those experienced by nuclear industry workers, medical professionals who use radiation in their practice, and people living near nuclear power plants or waste disposal sites. It also has applications in cancer treatment, where radiation is used to kill cancer cells but can also cause genetic damage.

Human chromosome pair 6 consists of two rod-shaped structures present in the nucleus of each human cell. They are identical in size and shape and contain genetic material, made up of DNA and proteins, that is essential for the development and function of the human body.

Chromosome pair 6 is one of the 23 pairs of chromosomes found in humans, with one chromosome inherited from each parent. Each chromosome contains thousands of genes that provide instructions for the production of proteins and regulate various cellular processes.

Chromosome pair 6 contains several important genes, including those involved in the development and function of the immune system, such as the major histocompatibility complex (MHC) genes. It also contains genes associated with certain genetic disorders, such as hereditary neuropathy with liability to pressure palsies (HNPP), a condition that affects the nerves, and Waardenburg syndrome, a disorder that affects pigmentation and hearing.

Abnormalities in chromosome pair 6 can lead to various genetic disorders, including numerical abnormalities such as trisomy 6 (three copies of chromosome 6) or monosomy 6 (only one copy of chromosome 6), as well as structural abnormalities such as deletions, duplications, or translocations of parts of the chromosome.

Triethylenemelamine (TEM) is not typically classified as a medication, but rather as a chemical compound. However, it has been used in the past in some experimental cancer treatments.

Medically, TEM is known as an alkylating agent, which means it works by chemically modifying and damaging the DNA of cells, preventing them from dividing and replicating. This makes it a potential antineoplastic agent, or a chemical used to treat cancer. However, due to its significant side effects and the development of more effective treatments, TEM is no longer commonly used in cancer therapy.

It's important to note that the use of TEM as a medical treatment is highly specialized and not routinely used in modern medicine. Always consult with a healthcare professional or pharmacist for accurate and up-to-date information on medical definitions and treatments.

Human chromosome pair 9 consists of two rod-shaped structures present in the nucleus of each cell of the human body. Each member of the pair contains thousands of genes and other genetic material, encoded in the form of DNA molecules. The two chromosomes in a pair are identical or very similar to each other in terms of their size, shape, and genetic makeup.

Chromosome 9 is one of the autosomal chromosomes, meaning that it is not a sex chromosome (X or Y) and is present in two copies in all cells of the body, regardless of sex. Chromosome 9 is a medium-sized chromosome, and it is estimated to contain around 135 million base pairs of DNA and approximately 1200 genes.

Chromosome 9 contains several important genes that are associated with various human traits and diseases. For example, mutations in the gene that encodes the protein APOE on chromosome 9 have been linked to an increased risk of developing Alzheimer's disease. Additionally, variations in the gene that encodes the protein EGFR on chromosome 9 have been associated with an increased risk of developing certain types of cancer.

Overall, human chromosome pair 9 plays a critical role in the development and function of the human body, and variations in its genetic makeup can contribute to a wide range of traits and diseases.

Metaphase is a phase in the cell division process (mitosis or meiosis) where the chromosomes align in the middle of the cell, also known as the metaphase plate or equatorial plane. During this stage, each chromosome consists of two sister chromatids attached to each other by a protein complex called the centromere. The spindle fibers from opposite poles of the cell attach to the centromeres of each chromosome, and through a process called congression, they align the chromosomes in the middle of the cell. This alignment allows for accurate segregation of genetic material during the subsequent anaphase stage.

Human chromosome pair 21 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and they are identical to each other. Chromosomes are made up of DNA, which contains genetic information that determines many of an individual's traits and characteristics.

Chromosome pair 21 is one of the 23 pairs of human autosomal chromosomes, meaning they are not sex chromosomes (X or Y). Chromosome pair 21 is the smallest of the human chromosomes, and it contains approximately 48 million base pairs of DNA. It contains around 200-300 genes that provide instructions for making proteins and regulating various cellular processes.

Down syndrome, a genetic disorder characterized by intellectual disability, developmental delays, distinct facial features, and sometimes heart defects, is caused by an extra copy of chromosome pair 21 or a part of it. This additional genetic material can lead to abnormalities in brain development and function, resulting in the characteristic symptoms of Down syndrome.

Linear Energy Transfer (LET) is a concept in radiation physics that describes the amount of energy that is transferred from an ionizing particle to a medium per unit length along its path. It is usually expressed in units of keV/μm (kiloelectron volts per micrometer). High-LET radiations, such as alpha particles and heavy ions, transfer more energy to the medium per unit length than low-LET radiations, such as X-rays and gamma rays. This results in a higher probability of producing dense ionizations and causing biological damage along the particle's path. Therefore, LET is an important factor in determining the relative biological effectiveness (RBE) of different types of radiation.

Micronuclei, chromosome-defective, refer to small additional nuclei that form during cell division when the genetic material is not properly divided between the two resulting daughter cells. These micronuclei can contain whole chromosomes or fragments of chromosomes that were not incorporated into either of the main nuclei during cell division. Chromosome-defective micronuclei are often associated with genomic instability, DNA damage, and chromosomal aberrations, which can lead to various health issues, including cancer and developmental defects. They can be used as a biomarker for genetic damage in cells and are commonly observed in response to exposure to mutagenic agents such as radiation or chemicals.

Human chromosome pair 18 consists of two rod-shaped structures present in the nucleus of each cell of the human body. Chromosomes are made up of DNA, protein, and RNA, and they carry genetic information that determines an individual's physical characteristics, biochemical processes, and susceptibility to disease.

Chromosome pair 18 is one of the 23 pairs of chromosomes that make up the human genome. Each member of chromosome pair 18 has a length of about 75 million base pairs and contains around 600 genes. Chromosome pair 18 is also known as the "smart chromosome" because it contains many genes involved in brain development, function, and cognition.

Abnormalities in chromosome pair 18 can lead to genetic disorders such as Edwards syndrome (trisomy 18), in which there is an extra copy of chromosome 18, or deletion of a portion of the chromosome, leading to various developmental and cognitive impairments.

Chromosomes in plants are thread-like structures that contain genetic material, DNA, and proteins. They are present in the nucleus of every cell and are inherited from the parent plants during sexual reproduction. Chromosomes come in pairs, with each pair consisting of one chromosome from each parent.

In plants, like in other organisms, chromosomes play a crucial role in inheritance, development, and reproduction. They carry genetic information that determines various traits and characteristics of the plant, such as its physical appearance, growth patterns, and resistance to diseases.

Plant chromosomes are typically much larger than those found in animals, making them easier to study under a microscope. The number of chromosomes varies among different plant species, ranging from as few as 2 in some ferns to over 1000 in certain varieties of wheat.

During cell division, the chromosomes replicate and then separate into two identical sets, ensuring that each new cell receives a complete set of genetic information. This process is critical for the growth and development of the plant, as well as for the production of viable seeds and offspring.

Chromosomes are thread-like structures that contain genetic material, made up of DNA and proteins, in the nucleus of cells. In humans, there are typically 46 chromosomes arranged in 23 pairs, with one member of each pair coming from each parent. The six pairs of chromosomes numbered 6 through 12, along with the X chromosome, are part of these 23 pairs and are referred to as autosomal chromosomes and a sex chromosome.

Human chromosome 6 is one of the autosomal chromosomes and contains an estimated 170 million base pairs and around 1,500 genes. It plays a role in several important functions, including immune response, cell signaling, and nervous system function.

Human chromosome 7 is another autosomal chromosome that contains approximately 159 million base pairs and around 1,200 genes. Chromosome 7 is best known for containing the gene for the cystic fibrosis transmembrane conductance regulator (CFTR) protein, whose mutations can lead to cystic fibrosis.

Human chromosome 8 is an autosomal chromosome that contains around 146 million base pairs and approximately 900 genes. Chromosome 8 has been associated with several genetic disorders, including Smith-Magenis syndrome and 8p deletion syndrome.

Human chromosome 9 is an autosomal chromosome that contains around 139 million base pairs and approximately 950 genes. Chromosome 9 has been linked to several genetic disorders, including Hereditary Spherocytosis and CHARGE syndrome.

Human chromosome 10 is an autosomal chromosome that contains around 135 million base pairs and approximately 800 genes. Chromosome 10 has been associated with several genetic disorders, including Dyschondrosteosis and Melanoma.

Human chromosome 11 is an autosomal chromosome that contains around 135 million base pairs and approximately 800 genes. Chromosome 11 has been linked to several genetic disorders, including Wilms tumor and Beckwith-Wiedemann syndrome.

Human chromosome 12 is an autosomal chromosome that contains around 133 million base pairs and approximately 750 genes. Chromosome 12 has been associated with several genetic disorders, including Charcot-Marie-Tooth disease type 1A and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP).

The X chromosome is one of the two sex chromosomes in humans. Females have two X chromosomes, while males have one X and one Y chromosome. The X chromosome contains around 155 million base pairs and approximately 1,000 genes. It has been linked to several genetic disorders, including Duchenne muscular dystrophy and Fragile X syndrome.

The Y chromosome is the other sex chromosome in humans. Males have one X and one Y chromosome, while females have two X chromosomes. The Y chromosome contains around 59 million base pairs and approximately 70 genes. It is primarily responsible for male sexual development and fertility.

In summary, the human genome consists of 23 pairs of chromosomes, including 22 autosomal pairs and one sex chromosome pair (XX in females and XY in males). The total length of the human genome is approximately 3 billion base pairs, and it contains around 20,000-25,000 protein-coding genes. Chromosomes are made up of DNA and proteins called histones, which help to package the DNA into a compact structure. The chromosomes contain genetic information that is passed down from parents to their offspring through reproduction.

Chromosomes in fungi are thread-like structures that contain genetic material, composed of DNA and proteins, present in the nucleus of a cell. Unlike humans and other eukaryotes that have a diploid number of chromosomes in their somatic cells, fungal chromosome numbers can vary widely between and within species.

Fungal chromosomes are typically smaller and fewer in number compared to those found in plants and animals. The chromosomal organization in fungi is also different from other eukaryotes. In many fungi, the chromosomes are condensed throughout the cell cycle, whereas in other eukaryotes, chromosomes are only condensed during cell division.

Fungi can have linear or circular chromosomes, depending on the species. For example, the model organism Saccharomyces cerevisiae (budding yeast) has a set of 16 small circular chromosomes, while other fungi like Neurospora crassa (red bread mold) and Aspergillus nidulans (a filamentous fungus) have linear chromosomes.

Fungal chromosomes play an essential role in the growth, development, reproduction, and survival of fungi. They carry genetic information that determines various traits such as morphology, metabolism, pathogenicity, and resistance to environmental stresses. Advances in genomic technologies have facilitated the study of fungal chromosomes, leading to a better understanding of their structure, function, and evolution.

Human chromosome pair 16 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.

Chromosomes come in pairs, with one chromosome inherited from each parent. Chromosome pair 16 contains two homologous chromosomes, which are similar in size, shape, and genetic content but may have slight variations due to differences in the DNA sequences inherited from each parent.

Chromosome pair 16 is one of the 22 autosomal pairs, meaning it contains non-sex chromosomes that are present in both males and females. Chromosome 16 is a medium-sized chromosome, and it contains around 2,800 genes that provide instructions for making proteins and regulating various cellular processes.

Abnormalities in chromosome pair 16 can lead to genetic disorders such as chronic myeloid leukemia, some forms of mental retardation, and other developmental abnormalities.

Human chromosome pair 2 consists of two rod-shaped structures present in the nucleus of each cell of the human body. Each member of the pair contains thousands of genes and other genetic material, encoded in the form of DNA molecules. Chromosomes are the physical carriers of inheritance, and human cells typically contain 23 pairs of chromosomes for a total of 46 chromosomes.

Chromosome pair 2 is one of the autosomal pairs, meaning that it is not a sex chromosome (X or Y). Each member of chromosome pair 2 is approximately 247 million base pairs in length and contains an estimated 1,000-1,300 genes. These genes play crucial roles in various biological processes, including development, metabolism, and response to environmental stimuli.

Abnormalities in chromosome pair 2 can lead to genetic disorders, such as cat-eye syndrome (CES), which is characterized by iris abnormalities, anal atresia, hearing loss, and intellectual disability. This disorder arises from the presence of an extra copy of a small region on chromosome 2, resulting in partial trisomy of this region. Other genetic conditions associated with chromosome pair 2 include proximal 2q13.3 microdeletion syndrome and Potocki-Lupski syndrome (PTLS).

Human chromosome pair 8 consists of two rod-shaped structures present in the nucleus of each cell of the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure known as a chromatin.

Human cells have 23 pairs of chromosomes, for a total of 46 chromosomes. Pair 8 is one of the autosomal pairs, meaning that it is not a sex chromosome (X or Y). Each member of chromosome pair 8 has a similar size, shape, and banding pattern, and they are identical in males and females.

Chromosome pair 8 contains several genes that are essential for various cellular functions and human development. Some of the genes located on chromosome pair 8 include those involved in the regulation of metabolism, nerve function, immune response, and cell growth and division.

Abnormalities in chromosome pair 8 can lead to genetic disorders such as Wolf-Hirschhorn syndrome, which is caused by a partial deletion of the short arm of chromosome 4, or partial trisomy 8, which results from an extra copy of all or part of chromosome 8. Both of these conditions are associated with developmental delays, intellectual disability, and various physical abnormalities.

Human chromosome pair 22 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.

Chromosome pair 22 is one of the 22 autosomal pairs of human chromosomes, meaning they are not sex chromosomes (X or Y). Chromosome 22 is the second smallest human chromosome, with each arm of the chromosome designated as p and q. The short arm is labeled "p," and the long arm is labeled "q."

Chromosome 22 contains several genes that are associated with various genetic disorders, including DiGeorge syndrome, velocardiofacial syndrome, and cat-eye syndrome, which result from deletions or duplications of specific regions on the chromosome. Additionally, chromosome 22 is the location of the NRXN1 gene, which has been associated with an increased risk for autism spectrum disorder (ASD) and schizophrenia when deleted or disrupted.

Understanding the genetic makeup of human chromosome pair 22 can provide valuable insights into human genetics, evolution, and disease susceptibility, as well as inform medical diagnoses, treatments, and research.

Mammalian chromosomes are thread-like structures that exist in the nucleus of mammalian cells, consisting of DNA, hist proteins, and RNA. They carry genetic information that is essential for the development and function of all living organisms. In mammals, each cell contains 23 pairs of chromosomes, for a total of 46 chromosomes, with one set inherited from the mother and the other from the father.

The chromosomes are typically visualized during cell division, where they condense and become visible under a microscope. Each chromosome is composed of two identical arms, separated by a constriction called the centromere. The short arm of the chromosome is labeled as "p," while the long arm is labeled as "q."

Mammalian chromosomes play a critical role in the transmission of genetic information from one generation to the next and are essential for maintaining the stability and integrity of the genome. Abnormalities in the number or structure of mammalian chromosomes can lead to various genetic disorders, including Down syndrome, Turner syndrome, and Klinefelter syndrome.

Chromosome pairing, also known as chromosome synapsis, is a process that occurs during meiosis, which is the type of cell division that results in the formation of sex cells or gametes (sperm and eggs).

In humans, each cell contains 23 pairs of chromosomes, for a total of 46 chromosomes. Of these, 22 pairs are called autosomal chromosomes, and they are similar in size and shape between the two copies in a pair. The last pair is called the sex chromosomes (X and Y), which determine the individual's biological sex.

During meiosis, homologous chromosomes (one from each parent) come together and pair up along their lengths in a process called synapsis. This pairing allows for the precise alignment of corresponding genes and genetic regions between the two homologous chromosomes. Once paired, the chromosomes exchange genetic material through a process called crossing over, which increases genetic diversity in the resulting gametes.

After crossing over, the homologous chromosomes separate during meiosis I, followed by the separation of sister chromatids (the two copies of each chromosome) during meiosis II. The end result is four haploid cells, each containing 23 chromosomes, which then develop into sperm or eggs.

Chromosome pairing is a crucial step in the process of sexual reproduction, ensuring that genetic information is accurately passed from one generation to the next while also promoting genetic diversity through recombination and independent assortment of chromosomes.

Human chromosome pair 10 refers to a group of genetic materials that are present in every cell of the human body. Chromosomes are thread-like structures that carry our genes and are located in the nucleus of most cells. They come in pairs, with one set inherited from each parent.

Chromosome pair 10 is one of the 22 autosomal chromosome pairs, meaning they contain genes that are not related to sex determination. Each member of chromosome pair 10 is a single, long DNA molecule that contains thousands of genes and other genetic material.

Chromosome pair 10 is responsible for carrying genetic information that influences various traits and functions in the human body. Some of the genes located on chromosome pair 10 are associated with certain medical conditions, such as hereditary breast and ovarian cancer syndrome, neurofibromatosis type 1, and Waardenburg syndrome type 2A.

It's important to note that while chromosomes carry genetic information, not all variations in the DNA sequence will result in a change in phenotype or function. Some variations may have no effect at all, while others may lead to changes in how proteins are made and function, potentially leading to disease or other health issues.

Human chromosome pair 19 refers to a group of 19 identical chromosomes that are present in every cell of the human body, except for the sperm and egg cells which contain only 23 chromosomes. Chromosomes are thread-like structures that carry genetic information in the form of DNA (deoxyribonucleic acid) molecules.

Each chromosome is made up of two arms, a shorter p arm and a longer q arm, separated by a centromere. Human chromosome pair 19 is an acrocentric chromosome, which means that the centromere is located very close to the end of the short arm (p arm).

Chromosome pair 19 contains approximately 58 million base pairs of DNA and encodes for around 1,400 genes. It is one of the most gene-dense chromosomes in the human genome, with many genes involved in important biological processes such as metabolism, immunity, and neurological function.

Abnormalities in chromosome pair 19 have been associated with various genetic disorders, including Sotos syndrome, which is characterized by overgrowth, developmental delay, and distinctive facial features, and Smith-Magenis syndrome, which is marked by intellectual disability, behavioral problems, and distinct physical features.

Human chromosome pair 12 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.

Chromosomes come in pairs, with one chromosome inherited from each parent. In humans, there are 23 pairs of chromosomes, for a total of 46 chromosomes in each cell. Chromosome pair 12 is the 12th pair of autosomal chromosomes, meaning they are not sex chromosomes (X or Y).

Chromosome 12 is a medium-sized chromosome and contains an estimated 130 million base pairs of DNA. It contains around 1,200 genes that provide instructions for making proteins and regulating various cellular processes. Some of the genes located on chromosome 12 include those involved in metabolism, development, and response to environmental stimuli.

Abnormalities in chromosome 12 can lead to genetic disorders, such as partial trisomy 12q, which is characterized by an extra copy of the long arm of chromosome 12, and Jacobsen syndrome, which is caused by a deletion of the distal end of the long arm of chromosome 12.

Artificial bacterial chromosomes (ABCs) are synthetic replicons that are designed to function like natural bacterial chromosomes. They are created through the use of molecular biology techniques, such as recombination and cloning, to construct large DNA molecules that can stably replicate and segregate within a host bacterium.

ABCs are typically much larger than traditional plasmids, which are smaller circular DNA molecules that can also replicate in bacteria but have a limited capacity for carrying genetic information. ABCs can accommodate large DNA inserts, making them useful tools for cloning and studying large genes, gene clusters, or even entire genomes of other organisms.

There are several types of ABCs, including bacterial artificial chromosomes (BACs), P1-derived artificial chromosomes (PACs), and yeast artificial chromosomes (YACs). BACs are the most commonly used type of ABC and can accommodate inserts up to 300 kilobases (kb) in size. They have been widely used in genome sequencing projects, functional genomics studies, and protein production.

Overall, artificial bacterial chromosomes provide a powerful tool for manipulating and studying large DNA molecules in a controlled and stable manner within bacterial hosts.

Trisomy is a genetic condition where there is an extra copy of a particular chromosome, resulting in 47 chromosomes instead of the typical 46 in a cell. This usually occurs due to an error in cell division during the development of the egg, sperm, or embryo.

Instead of the normal pair, there are three copies (trisomy) of that chromosome. The most common form of trisomy is Trisomy 21, also known as Down syndrome, where there is an extra copy of chromosome 21. Other forms include Trisomy 13 (Patau syndrome) and Trisomy 18 (Edwards syndrome), which are associated with more severe developmental issues and shorter lifespans.

Trisomy can also occur in a mosaic form, where some cells have the extra chromosome while others do not, leading to varying degrees of symptoms depending on the proportion of affected cells.

Human chromosome pair 5 consists of two rod-shaped structures present in the nucleus of human cells, which contain genetic material in the form of DNA and proteins. Each member of chromosome pair 5 is a single chromosome, and humans typically have 23 pairs of chromosomes for a total of 46 chromosomes in every cell of their body (except gametes or sex cells, which contain 23 chromosomes).

Chromosome pair 5 is one of the autosomal pairs, meaning it is not a sex chromosome. Each member of chromosome pair 5 is approximately 197 million base pairs in length and contains around 800-900 genes that provide instructions for making proteins and regulating various cellular processes.

Chromosome pair 5 is associated with several genetic disorders, including cri du chat syndrome (resulting from a deletion on the short arm of chromosome 5), Prader-Willi syndrome and Angelman syndrome (both resulting from abnormalities in gene expression on the long arm of chromosome 5).

Human Y chromosomes are one of the two sex-determining chromosomes in humans (the other being the X chromosome). They are found in the 23rd pair of human chromosomes and are significantly smaller than the X chromosome.

The Y chromosome is passed down from father to son through the paternal line, and it plays a crucial role in male sex determination. The SRY gene (sex-determining region Y) on the Y chromosome initiates the development of male sexual characteristics during embryonic development.

In addition to the SRY gene, the human Y chromosome contains several other genes that are essential for sperm production and male fertility. However, the Y chromosome has a much lower gene density compared to other chromosomes, with only about 80 protein-coding genes, making it one of the most gene-poor chromosomes in the human genome.

Because of its small size and low gene density, the Y chromosome is particularly susceptible to genetic mutations and deletions, which can lead to various genetic disorders and male infertility. Nonetheless, the Y chromosome remains a critical component of human genetics and evolution, providing valuable insights into sex determination, inheritance patterns, and human diversity.

DNA damage refers to any alteration in the structure or composition of deoxyribonucleic acid (DNA), which is the genetic material present in cells. DNA damage can result from various internal and external factors, including environmental exposures such as ultraviolet radiation, tobacco smoke, and certain chemicals, as well as normal cellular processes such as replication and oxidative metabolism.

Examples of DNA damage include base modifications, base deletions or insertions, single-strand breaks, double-strand breaks, and crosslinks between the two strands of the DNA helix. These types of damage can lead to mutations, genomic instability, and chromosomal aberrations, which can contribute to the development of diseases such as cancer, neurodegenerative disorders, and aging-related conditions.

The body has several mechanisms for repairing DNA damage, including base excision repair, nucleotide excision repair, mismatch repair, and double-strand break repair. However, if the damage is too extensive or the repair mechanisms are impaired, the cell may undergo apoptosis (programmed cell death) to prevent the propagation of potentially harmful mutations.

Chromosomal instability is a term used in genetics to describe a type of genetic alteration where there are abnormalities in the number or structure of chromosomes within cells. Chromosomes are thread-like structures that contain our genetic material, and they usually exist in pairs in the nucleus of a cell.

Chromosomal instability can arise due to various factors, including errors in DNA replication or repair, problems during cell division, or exposure to environmental mutagens. This instability can lead to an increased frequency of chromosomal abnormalities, such as deletions, duplications, translocations, or changes in the number of chromosomes.

Chromosomal instability is associated with several human diseases, including cancer. In cancer cells, chromosomal instability can contribute to tumor heterogeneity, drug resistance, and disease progression. It is also observed in certain genetic disorders, such as Down syndrome, where an extra copy of chromosome 21 is present, and in some rare inherited syndromes, such as Bloom syndrome and Fanconi anemia, which are characterized by a high risk of cancer and other health problems.

Human chromosomes are the thread-like structures located in the nucleus of human cells, which carry genetic information in the form of DNA. Humans have a total of 46 chromosomes arranged in 23 pairs. The first 22 pairs are called autosomes, and the last pair are the sex chromosomes, X and Y.

Chromosomes 1-3 are the largest human chromosomes, and they contain a significant portion of the human genome. Here is a brief overview of each:

1. Chromosome 1: This is the largest human chromosome, spanning about 8% of the human genome. It contains approximately 2,800 genes that are responsible for various functions such as cell growth and division, nerve function, and response to stimuli.
2. Chromosome 2: The second largest human chromosome, spanning about 7% of the human genome. It contains approximately 2,300 genes that are involved in various functions such as metabolism, development, and immune response.
3. Chromosome 3: This is the third largest human chromosome, spanning about 6% of the human genome. It contains approximately 1,900 genes that are responsible for various functions such as DNA repair, cell signaling, and response to stress.

It's worth noting that while these chromosomes contain a large number of genes, they also have significant amounts of non-coding DNA, which means that not all of the genetic material on these chromosomes is responsible for encoding proteins or other functional elements.

A chromosome is a thread-like structure that contains genetic material, made up of DNA and proteins, in the nucleus of a cell. In humans, there are 23 pairs of chromosomes, for a total of 46 chromosomes, in each cell of the body, with the exception of the sperm and egg cells which contain only 23 chromosomes.

The X chromosome is one of the two sex-determining chromosomes in humans. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The X chromosome contains hundreds of genes that are responsible for various functions in the body, including some related to sexual development and reproduction.

Humans inherit one X chromosome from their mother and either an X or a Y chromosome from their father. In females, one of the two X chromosomes is randomly inactivated during embryonic development, resulting in each cell having only one active X chromosome. This process, known as X-inactivation, helps to ensure that females have roughly equal levels of gene expression from the X chromosome, despite having two copies.

Abnormalities in the number or structure of the X chromosome can lead to various genetic disorders, such as Turner syndrome (X0), Klinefelter syndrome (XXY), and fragile X syndrome (an X-linked disorder caused by a mutation in the FMR1 gene).

Chromatids are defined as the individual strands that make up a duplicated chromosome. They are formed during the S phase of the cell cycle, when replication occurs and each chromosome is copied, resulting in two identical sister chromatids. These chromatids are connected at a region called the centromere and are held together by cohesin protein complexes until they are separated during mitosis or meiosis.

During mitosis, the sister chromatids are pulled apart by the mitotic spindle apparatus and distributed equally to each daughter cell. In meiosis, which is a type of cell division that occurs in the production of gametes (sex cells), homologous chromosomes pair up and exchange genetic material through a process called crossing over. After crossing over, each homologous chromosome consists of two recombinant chromatids that are separated during meiosis I, and then sister chromatids are separated during meiosis II.

Chromatids play an essential role in the faithful transmission of genetic information from one generation to the next, ensuring that each daughter cell or gamete receives a complete set of chromosomes with intact and functional genes.

A dose-response relationship in radiation refers to the correlation between the amount of radiation exposure (dose) and the biological response or adverse health effects observed in exposed individuals. As the level of radiation dose increases, the severity and frequency of the adverse health effects also tend to increase. This relationship is crucial in understanding the risks associated with various levels of radiation exposure and helps inform radiation protection standards and guidelines.

The effects of ionizing radiation can be categorized into two types: deterministic and stochastic. Deterministic effects have a threshold dose below which no effect is observed, and above this threshold, the severity of the effect increases with higher doses. Examples include radiation-induced cataracts or radiation dermatitis. Stochastic effects, on the other hand, do not have a clear threshold and are based on probability; as the dose increases, so does the likelihood of the adverse health effect occurring, such as an increased risk of cancer.

Understanding the dose-response relationship in radiation exposure is essential for setting limits on occupational and public exposure to ionizing radiation, optimizing radiation protection practices, and developing effective medical countermeasures in case of radiation emergencies.

Human chromosome pair 14 consists of two rod-shaped structures present in the nucleus of human cells, which contain genetic material in the form of DNA and proteins. Each member of the pair contains a single very long DNA molecule that carries an identical set of genes and other genetic elements, totaling approximately 105 million base pairs. These chromosomes play a crucial role in the development, functioning, and reproduction of human beings.

Chromosome 14 is one of the autosomal chromosomes, meaning it is not involved in determining the sex of an individual. It contains around 800-1,000 genes that provide instructions for producing various proteins responsible for numerous cellular functions and processes. Some notable genes located on chromosome 14 include those associated with neurodevelopmental disorders, cancer susceptibility, and immune system regulation.

Human cells typically have 23 pairs of chromosomes, including 22 autosomal pairs (numbered 1-22) and one pair of sex chromosomes (XX for females or XY for males). Chromosome pair 14 is the eighth largest autosomal pair in terms of its total length.

It's important to note that genetic information on chromosome 14, like all human chromosomes, can vary between individuals due to genetic variations and mutations. These differences contribute to the unique characteristics and traits found among humans.

Background radiation refers to the ionizing radiation that is present in the natural environment and originates from various sources, both natural and human-made. The term "background" indicates that this radiation exists as a constant presence that is always present, even if at low levels.

The primary sources of natural background radiation include:

1. Cosmic radiation: High-energy particles from space, such as protons and alpha particles, continuously bombard the Earth's atmosphere. When these particles collide with atoms in the atmosphere, they produce secondary particles called muons and neutrinos, which can penetrate through buildings and living tissues, contributing to background radiation exposure.
2. Terrestrial radiation: Radioactive elements present in the Earth's crust, such as uranium, thorium, and potassium-40, emit alpha and gamma radiation. These radioactive elements are found in rocks, soil, and building materials, leading to varying levels of background radiation depending on location.
3. Radon: A naturally occurring radioactive gas produced by the decay of radium, which is present in trace amounts in rocks and soil. Radon can accumulate in buildings, particularly in basements and crawl spaces, leading to increased exposure for occupants.

Human-made sources of background radiation include medical diagnostic procedures (e.g., X-rays and CT scans), consumer products (e.g., smoke detectors containing americium-241), and residual nuclear fallout from past nuclear weapons testing or accidents, such as the Chernobyl disaster.

It is important to note that background radiation levels vary significantly depending on location, altitude, geology, and other factors. While it is not possible to avoid background radiation entirely, understanding its sources and taking appropriate precautions when exposed to higher levels (e.g., limiting time in high radon areas) can help minimize potential health risks associated with ionizing radiation exposure.

Human chromosome pair 20 is one of the 23 pairs of human chromosomes present in every cell of the body, except for the sperm and egg cells which contain only 23 individual chromosomes. Chromosomes are thread-like structures that carry genetic information in the form of genes.

Human chromosome pair 20 is an acrocentric chromosome, meaning it has a short arm (p arm) and a long arm (q arm), with the centromere located near the junction of the two arms. The short arm of chromosome 20 is very small and contains few genes, while the long arm contains several hundred genes that play important roles in various biological processes.

Chromosome pair 20 is associated with several genetic disorders, including DiGeorge syndrome, which is caused by a deletion of a portion of the long arm of chromosome 20. This syndrome is characterized by birth defects affecting the heart, face, and immune system. Other conditions associated with abnormalities of chromosome pair 20 include some forms of intellectual disability, autism spectrum disorder, and cancer.

'Azure stains' is a term used in pathology to describe a histological staining technique that uses a type of dye called methyl blue, which turns the stained structures a blue-purple color. This technique is often used to stain acid mucins, which are found in various types of tissues and can be indicative of certain medical conditions.

In particular, azure stains are sometimes used to help diagnose certain types of cancer, such as mucoepidermoid carcinoma, a type of salivary gland tumor that produces acid mucins. The staining technique can help pathologists identify the presence and distribution of these mucins within the tumor cells, which can aid in making an accurate diagnosis and determining the best course of treatment.

It's worth noting that there are several different types of histological stains that use various dyes to highlight different structures or features within tissues. Azure stains are just one example of these techniques, and they are typically used in conjunction with other staining methods to provide a comprehensive picture of the tissue being examined.

A "Radioactive Hazard Release" is defined in medical and environmental health terms as an uncontrolled or accidental release of radioactive material into the environment, which can pose significant risks to human health and the ecosystem. This can occur due to various reasons such as nuclear accidents, improper handling or disposal of radioactive sources, or failure of radiation-generating equipment.

The released radioactive materials can contaminate air, water, and soil, leading to both external and internal exposure pathways. External exposure occurs through direct contact with the skin or by inhaling radioactive particles, while internal exposure happens when radioactive substances are ingested or inhaled and become deposited within the body.

The health effects of radioactive hazard release depend on several factors, including the type and amount of radiation released, the duration and intensity of exposure, and the sensitivity of the exposed individuals. Potential health impacts range from mild radiation sickness to severe diseases such as cancer and genetic mutations, depending on the level and length of exposure.

Prompt identification, assessment, and management of radioactive hazard releases are crucial to minimize potential health risks and protect public health.

Human chromosome pair 15 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.

Chromosomes come in pairs, with one chromosome inherited from each parent. Chromosome pair 15 includes two homologous chromosomes, meaning they have the same size, shape, and gene content but may contain slight variations in their DNA sequences.

These chromosomes play a crucial role in inheritance and the development and function of the human body. Chromosome pair 15 contains around 100 million base pairs of DNA and approximately 700 protein-coding genes, which are involved in various biological processes such as growth, development, metabolism, and regulation of gene expression.

Abnormalities in chromosome pair 15 can lead to genetic disorders, including Prader-Willi syndrome and Angelman syndrome, which are caused by the loss or alteration of specific regions on chromosome 15.

Styrene is not typically referred to as "Styrenes" in a medical context. Instead, it is simply called Styrene. Here is a medical definition for it:

Styrene is an organic compound with the chemical formula C8H8. It is a colorless oily liquid that evaporates easily and has a sweet smell and taste. Styrene is used in the manufacture of polystyrene plastics and resins, as well as in rubber and latex manufacturing.

In terms of its health effects, styrene is classified as a possible carcinogen by the International Agency for Research on Cancer (IARC). Exposure to high levels of styrene can cause neurological symptoms such as headache, fatigue, and difficulty concentrating. Long-term exposure has been linked to an increased risk of certain types of cancer, including leukemia and lymphoma. However, the evidence for these associations is not conclusive, and more research is needed to fully understand the health effects of styrene exposure.

Mosaicism, in the context of genetics and medicine, refers to the presence of two or more cell lines with different genetic compositions in an individual who has developed from a single fertilized egg. This means that some cells have one genetic makeup, while others have a different genetic makeup. This condition can occur due to various reasons such as errors during cell division after fertilization.

Mosaicism can involve chromosomes (where whole or parts of chromosomes are present in some cells but not in others) or it can involve single genes (where a particular gene is present in one form in some cells and a different form in others). The symptoms and severity of mosaicism can vary widely, depending on the type and location of the genetic difference and the proportion of cells that are affected. Some individuals with mosaicism may not experience any noticeable effects, while others may have significant health problems.

Mitosis is a type of cell division in which the genetic material of a single cell, called the mother cell, is equally distributed into two identical daughter cells. It's a fundamental process that occurs in multicellular organisms for growth, maintenance, and repair, as well as in unicellular organisms for reproduction.

The process of mitosis can be broken down into several stages: prophase, prometaphase, metaphase, anaphase, and telophase. During prophase, the chromosomes condense and become visible, and the nuclear envelope breaks down. In prometaphase, the nuclear membrane is completely disassembled, and the mitotic spindle fibers attach to the chromosomes at their centromeres.

During metaphase, the chromosomes align at the metaphase plate, an imaginary line equidistant from the two spindle poles. In anaphase, sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell. Finally, in telophase, new nuclear envelopes form around each set of chromosomes, and the chromosomes decondense and become less visible.

Mitosis is followed by cytokinesis, a process that divides the cytoplasm of the mother cell into two separate daughter cells. The result of mitosis and cytokinesis is two genetically identical cells, each with the same number and kind of chromosomes as the original parent cell.

The Mitotic Index (MI) is a measure of cell proliferation that reflects the percentage of cells in a population or sample that are undergoing mitosis, which is the process of cell division. It is often expressed as the number of mitotic figures (dividing cells) per 100 or 1,000 cells counted in a microscopic field. The Mitotic Index is used in various fields, including pathology and research, to assess the growth fraction of cells in tissues or cultures, and to monitor the effects of treatments that affect cell division, such as chemotherapy or radiation therapy.

Aberrometry is a medical diagnostic technique used to measure the amount and type of aberration or distortion in the optical system of the eye. It is often used to evaluate the quality of vision, particularly in cases where traditional methods of measuring visual acuity are not sufficient.

During an aberrometry test, the patient looks into a specialized instrument called a wavefront sensor while a series of light patterns are projected onto the retina. The sensor then measures how the light is distorted as it passes through the eye's optical system, including the cornea and lens. This information is used to create a detailed map of the eye's aberrations, which can help doctors identify any irregularities that may be contributing to visual symptoms such as blurred vision, glare, or halos around lights.

Aberrometry is often used in conjunction with other diagnostic tests to evaluate patients who are considering refractive surgery, such as LASIK or PRK. By identifying any abnormalities in the eye's optical system, doctors can determine whether a patient is a good candidate for surgery and make more informed decisions about how to proceed with treatment.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Alpha particles are a type of radiation that consist of two protons and two neutrons. They are essentially the nuclei of helium atoms and are produced during the decay of radioactive isotopes, such as uranium or radon. When an alpha particle is emitted from a radioactive atom, it carries away energy and causes the atom to transform into a different element with a lower atomic number and mass number.

Alpha particles have a positive charge and are relatively massive compared to other types of radiation, such as beta particles (which are high-energy electrons) or gamma rays (which are high-energy photons). Because of their charge and mass, alpha particles can cause significant ionization and damage to biological tissue. However, they have a limited range in air and cannot penetrate the outer layers of human skin, making them generally less hazardous than other forms of radiation if exposure is external.

Internal exposure to alpha-emitting radionuclides, however, can be much more dangerous because alpha particles can cause significant damage to cells and DNA when they are emitted inside the body. This is why inhaling or ingesting radioactive materials that emit alpha particles can pose a serious health risk.

Chromosomes are thread-like structures located in the nucleus of cells that contain most of the DNA present in cells. They come in pairs, with one set inherited from each parent. In humans, there are typically 23 pairs of chromosomes, for a total of 46 chromosomes.

Chromosomes 16-18 refer to the specific chromosomes that make up the 16th and 17th pairs in human cells. Chromosome 16 is an acrocentric chromosome, meaning it has a short arm (p arm) and a long arm (q arm), with the centromere located near the middle of the chromosome. It contains around 115 million base pairs of DNA and encodes approximately 1,100 genes.

Chromosome 17 is a metacentric chromosome, meaning it has a centromere located in the middle, dividing the chromosome into two arms of equal length. It contains around 81 million base pairs of DNA and encodes approximately 1,300 genes.

Chromosome 18 is a small acrocentric chromosome with a short arm (p arm) and a long arm (q arm), with the centromere located near the end of the short arm. It contains around 76 million base pairs of DNA and encodes approximately 1,200 genes.

Abnormalities in these chromosomes can lead to various genetic disorders, such as Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), and some forms of Down syndrome (translocation between chromosomes 14 and 21).

I'm sorry for any confusion, but "Hempa" is not a term commonly used in medical terminology. It's possible that there may be a typo or misunderstanding in the term you're looking for. If you're referring to "hemp," I can provide some information related to this.

Hemp is a variety of the Cannabis sativa plant species that is grown specifically for industrial purposes. It has very low concentrations of tetrahydrocannabinol (THC), the main psychoactive compound found in cannabis, making it unsuitable for use as a recreational drug. Hemp is used to produce a wide range of products, including textiles, paper, rope, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.

If you meant to ask about something else or if there's more information you need regarding hemp, please let me know!

Genetic markers are specific segments of DNA that are used in genetic mapping and genotyping to identify specific genetic locations, diseases, or traits. They can be composed of short tandem repeats (STRs), single nucleotide polymorphisms (SNPs), restriction fragment length polymorphisms (RFLPs), or variable number tandem repeats (VNTRs). These markers are useful in various fields such as genetic research, medical diagnostics, forensic science, and breeding programs. They can help to track inheritance patterns, identify genetic predispositions to diseases, and solve crimes by linking biological evidence to suspects or victims.

Gamma rays are a type of ionizing radiation that is released from the nucleus of an atom during radioactive decay. They are high-energy photons, with wavelengths shorter than 0.01 nanometers and frequencies greater than 3 x 10^19 Hz. Gamma rays are electromagnetic radiation, similar to X-rays, but with higher energy levels and the ability to penetrate matter more deeply. They can cause damage to living tissue and are used in medical imaging and cancer treatment.

I'm sorry for any confusion, but "Kazakhstan" is not a medical term or concept. It is the world's largest landlocked country, located in Central Asia. If you have any questions about medical terms or concepts, I would be happy to help with those!

Artificial chromosomes, yeast are synthetic chromosomes that have been created in the laboratory and can function in yeast cells. They are made up of DNA sequences that have been chemically synthesized or engineered from existing yeast chromosomes. These artificial chromosomes can be used to introduce new genes or modify existing ones in yeast, allowing for the study of gene function and genetic interactions in a controlled manner.

The creation of artificial chromosomes in yeast has been an important tool in biotechnology and synthetic biology, enabling the development of novel industrial processes and the engineering of yeast strains with enhanced properties for various applications, such as biofuel production or the manufacture of pharmaceuticals. Additionally, the study of artificial chromosomes in yeast has provided valuable insights into the fundamental principles of genome organization, replication, and inheritance.

Relative Biological Effectiveness (RBE) is a term used in radiation biology and medicine to describe the relative effectiveness of different types or energies of ionizing radiation in causing biological damage, compared to a reference radiation such as high-energy photons (X-rays or gamma rays). RBE takes into account the differences in biological impact between various types of radiation, which can be due to differences in linear energy transfer (LET), quality factor, and other factors. It is used to estimate the biological effects of mixed radiation fields, such as those encountered in radiotherapy treatments that combine different types or energies of radiation. The RBE value for a specific type of radiation is determined through experimental studies that compare its biological impact to that of the reference radiation.

Human chromosomes 13-15 are part of a set of 23 pairs of chromosomes found in the cells of the human body. Chromosomes are thread-like structures that contain genetic material, or DNA, that is inherited from each parent. They are responsible for the development and function of all the body's organs and systems.

Chromosome 13 is a medium-sized chromosome and contains an estimated 114 million base pairs of DNA. It is associated with several genetic disorders, including cri du chat syndrome, which is caused by a deletion on the short arm of the chromosome. Chromosome 13 also contains several important genes, such as those involved in the production of enzymes and proteins that help regulate growth and development.

Chromosome 14 is a medium-sized chromosome and contains an estimated 107 million base pairs of DNA. It is known to contain many genes that are important for the normal functioning of the brain and nervous system, as well as genes involved in the production of immune system proteins. Chromosome 14 is also associated with a number of genetic disorders, including Wolf-Hirschhorn syndrome, which is caused by a deletion on the short arm of the chromosome.

Chromosome 15 is a medium-sized chromosome and contains an estimated 102 million base pairs of DNA. It is associated with several genetic disorders, including Prader-Willi syndrome and Angelman syndrome, which are caused by abnormalities in the expression of genes on the chromosome. Chromosome 15 also contains important genes involved in the regulation of growth and development, as well as genes that play a role in the production of neurotransmitters, the chemical messengers of the brain.

It is worth noting that while chromosomes 13-15 are important for normal human development and function, abnormalities in these chromosomes can lead to a variety of genetic disorders and developmental issues.

Isochromosomes are abnormal chromosomes that contain identical arms on both sides, instead of having one arm longer than the other. This occurs due to an error in cell division where the centromere, the region where the chromatids (the two copies of chromosome) are attached, is duplicated and then separated improperly. As a result, each new chromosome has two identical arms.

Isochromosomes can lead to genetic disorders because they can disrupt the balance of genes on the chromosome. For example, if an isochromosome forms for chromosome 18 (i(18)), there will be three copies of the genes on one arm and only one copy on the other arm, leading to an overexpression of some genes and a loss of expression of others. This can cause developmental abnormalities and intellectual disabilities.

Isochromosomes are often associated with certain types of cancer, as well as genetic disorders such as Turner syndrome and Klinefelter syndrome.

I must clarify that "Armenia" is not a medical term or condition. It's the name of a country located in the South Caucasus region, situated at the crossroads of Western Asia and Eastern Europe. Armenia is known for its rich history, unique culture, and natural beauty.

If you have any questions related to medical conditions, diseases, or healthcare practices in Armenia, I would be happy to help answer those. However, it's important to note that providing a medical definition of a country isn't applicable.

Nucleic acid hybridization is a process in molecular biology where two single-stranded nucleic acids (DNA, RNA) with complementary sequences pair together to form a double-stranded molecule through hydrogen bonding. The strands can be from the same type of nucleic acid or different types (i.e., DNA-RNA or DNA-cDNA). This process is commonly used in various laboratory techniques, such as Southern blotting, Northern blotting, polymerase chain reaction (PCR), and microarray analysis, to detect, isolate, and analyze specific nucleic acid sequences. The hybridization temperature and conditions are critical to ensure the specificity of the interaction between the two strands.

Genetic linkage is the phenomenon where two or more genetic loci (locations on a chromosome) tend to be inherited together because they are close to each other on the same chromosome. This occurs during the process of sexual reproduction, where homologous chromosomes pair up and exchange genetic material through a process called crossing over.

The closer two loci are to each other on a chromosome, the lower the probability that they will be separated by a crossover event. As a result, they are more likely to be inherited together and are said to be linked. The degree of linkage between two loci can be measured by their recombination frequency, which is the percentage of meiotic events in which a crossover occurs between them.

Linkage analysis is an important tool in genetic research, as it allows researchers to identify and map genes that are associated with specific traits or diseases. By analyzing patterns of linkage between markers (identifiable DNA sequences) and phenotypes (observable traits), researchers can infer the location of genes that contribute to those traits or diseases on chromosomes.

Human chromosomes are thread-like structures that contain genetic material, composed of DNA and proteins, present in the nucleus of human cells. Each chromosome is a single, long DNA molecule that carries hundreds to thousands of genes.

Chromosomes 21, 22, and Y are three of the 23 pairs of human chromosomes. Here's what you need to know about each:

* Chromosome 21 is the smallest human autosomal chromosome, with a total length of about 47 million base pairs. It contains an estimated 200-300 genes and is associated with several genetic disorders, most notably Down syndrome, which occurs when there is an extra copy of this chromosome (trisomy 21).
* Chromosome 22 is the second smallest human autosomal chromosome, with a total length of about 50 million base pairs. It contains an estimated 500-600 genes and is associated with several genetic disorders, including DiGeorge syndrome and cat-eye syndrome.
* The Y chromosome is one of the two sex chromosomes (the other being the X chromosome) and is found only in males. It is much smaller than the X chromosome, with a total length of about 59 million base pairs and an estimated 70-200 genes. The Y chromosome determines maleness by carrying the gene for the testis-determining factor (TDF), which triggers male development in the embryo.

It's worth noting that while we have a standard set of 23 pairs of chromosomes, there can be variations and abnormalities in the number or structure of these chromosomes that can lead to genetic disorders.

A chromosome inversion is a genetic rearrangement where a segment of a chromosome has been reversed end to end, so that its order of genes is opposite to the original. This means that the gene sequence on the segment of the chromosome has been inverted.

In an inversion, the chromosome breaks in two places, and the segment between the breaks rotates 180 degrees before reattaching. This results in a portion of the chromosome being inverted, or turned upside down, relative to the rest of the chromosome.

Chromosome inversions can be either paracentric or pericentric. Paracentric inversions involve a segment that does not include the centromere (the central constriction point of the chromosome), while pericentric inversions involve a segment that includes the centromere.

Inversions can have various effects on an individual's phenotype, depending on whether the inversion involves genes and if so, how those genes are affected by the inversion. In some cases, inversions may have no noticeable effect, while in others they may cause genetic disorders or predispose an individual to certain health conditions.

Interphase is a phase in the cell cycle during which the cell primarily performs its functions of growth and DNA replication. It is the longest phase of the cell cycle, consisting of G1 phase (during which the cell grows and prepares for DNA replication), S phase (during which DNA replication occurs), and G2 phase (during which the cell grows further and prepares for mitosis). During interphase, the chromosomes are in their relaxed, extended form and are not visible under the microscope. Interphase is followed by mitosis, during which the chromosomes condense and separate to form two genetically identical daughter cells.

Cricetinae is a subfamily of rodents that includes hamsters, gerbils, and relatives. These small mammals are characterized by having short limbs, compact bodies, and cheek pouches for storing food. They are native to various parts of the world, particularly in Europe, Asia, and Africa. Some species are popular pets due to their small size, easy care, and friendly nature. In a medical context, understanding the biology and behavior of Cricetinae species can be important for individuals who keep them as pets or for researchers studying their physiology.

Radiation injuries refer to the damages that occur to living tissues as a result of exposure to ionizing radiation. These injuries can be acute, occurring soon after exposure to high levels of radiation, or chronic, developing over a longer period after exposure to lower levels of radiation. The severity and type of injury depend on the dose and duration of exposure, as well as the specific tissues affected.

Acute radiation syndrome (ARS), also known as radiation sickness, is the most severe form of acute radiation injury. It can cause symptoms such as nausea, vomiting, diarrhea, fatigue, fever, and skin burns. In more severe cases, it can lead to neurological damage, hemorrhage, infection, and death.

Chronic radiation injuries, on the other hand, may not appear until months or even years after exposure. They can cause a range of symptoms, including fatigue, weakness, skin changes, cataracts, reduced fertility, and an increased risk of cancer.

Radiation injuries can be treated with supportive care, such as fluids and electrolytes replacement, antibiotics, wound care, and blood transfusions. In some cases, surgery may be necessary to remove damaged tissue or control bleeding. Prevention is the best approach to radiation injuries, which includes limiting exposure through proper protective measures and monitoring radiation levels in the environment.

Radiation dosage, in the context of medical physics, refers to the amount of radiation energy that is absorbed by a material or tissue, usually measured in units of Gray (Gy), where 1 Gy equals an absorption of 1 Joule of radiation energy per kilogram of matter. In the clinical setting, radiation dosage is used to plan and assess the amount of radiation delivered to a patient during treatments such as radiotherapy. It's important to note that the biological impact of radiation also depends on other factors, including the type and energy level of the radiation, as well as the sensitivity of the irradiated tissues or organs.

A ring chromosome is a structurally abnormal chromosome that has formed a circle or ring shape. This occurs when both ends of the chromosome break off and the resulting fragments join together to form a circular structure. Ring chromosomes can vary in size, and the loss of genetic material during the formation of the ring can lead to genetic disorders and developmental delays. The effects of a ring chromosome depend on the location of the breakpoints and the amount of genetic material lost. Some individuals with ring chromosomes may have mild symptoms, while others may have severe disabilities or health problems.

Corneal topography is a non-invasive medical imaging technique used to create a detailed map of the surface curvature of the cornea, which is the clear, dome-shaped surface at the front of the eye. This procedure provides valuable information about the shape and condition of the cornea, helping eye care professionals assess various eye conditions such as astigmatism, keratoconus, and other corneal abnormalities. It can also be used in contact lens fitting, refractive surgery planning, and post-surgical evaluation.

The Comet Assay, also known as single-cell gel electrophoresis (SCGE), is a sensitive method used to detect and measure DNA damage at the level of individual cells. The assay gets its name from the comet-like shape that formed DNA fragments migrate towards the anode during electrophoresis, creating a "tail" that represents the damaged DNA.

In this assay, cells are embedded in low melting point agarose on a microscope slide and then lysed to remove the cell membranes and histones, leaving the DNA intact. The slides are then subjected to electrophoresis under neutral or alkaline conditions, which causes the negatively charged DNA fragments to migrate out of the nucleus towards the anode. After staining with a DNA-binding dye, the slides are visualized under a fluorescence microscope and the degree of DNA damage is quantified by measuring the length and intensity of the comet "tail."

The Comet Assay is widely used in genetic toxicology to assess the genotoxic potential of chemicals, drugs, and environmental pollutants. It can also be used to measure DNA repair capacity and oxidative DNA damage.

Chromosomes are thread-like structures located in the nucleus of cells that carry genetic information in the form of genes. In humans, there are 23 pairs of chromosomes for a total of 46 chromosomes in every cell of the body, except for the sperm and egg cells which contain only 23 chromosomes.

Human chromosomes are numbered from 1 to 22, based on their size, with chromosome 1 being the largest and chromosome 22 being the smallest. The last two pairs of human chromosomes are known as the sex chromosomes because they determine a person's biological sex. These are labeled X and Y, with females having two X chromosomes (44+XX) and males having one X and one Y chromosome (44+XY).

Therefore, "Chromosomes, Human, 4-5" refers to the fourth and fifth pairs of human chromosomes. Chromosome 4 is an acrocentric chromosome, meaning its centromere is located near one end, resulting in a short arm (p) and a long arm (q). It contains about 190 million base pairs and encodes approximately 700 genes.

Chromosome 5 is a submetacentric chromosome, with the centromere located closer to the middle, creating two arms of roughly equal length: the short arm (p) and the long arm (q). It contains about 182 million base pairs and encodes approximately 900 genes.

Both chromosomes 4 and 5 are involved in various genetic disorders when abnormalities occur, such as deletions, duplications, or translocations. Some of the well-known genetic conditions associated with these chromosomes include:

* Chromosome 4: Wolf-Hirschhorn syndrome (deletion), Charcot-Marie-Tooth disease type 1A (duplication)
* Chromosome 5: Cri du Chat syndrome (deletion), Duchenne muscular dystrophy (deletion or mutation in a gene located on chromosome 5)

"Cricetulus" is a genus of rodents that includes several species of hamsters. These small, burrowing animals are native to Asia and have a body length of about 8-15 centimeters, with a tail that is usually shorter than the body. They are characterized by their large cheek pouches, which they use to store food. Some common species in this genus include the Chinese hamster (Cricetulus griseus) and the Daurian hamster (Cricetulus dauuricus). These animals are often kept as pets or used in laboratory research.

Ionizing radiation is a type of radiation that carries enough energy to ionize atoms or molecules, which means it can knock electrons out of their orbits and create ions. These charged particles can cause damage to living tissue and DNA, making ionizing radiation dangerous to human health. Examples of ionizing radiation include X-rays, gamma rays, and some forms of subatomic particles such as alpha and beta particles. The amount and duration of exposure to ionizing radiation are important factors in determining the potential health effects, which can range from mild skin irritation to an increased risk of cancer and other diseases.

Chromosome positioning, also known as chromosome organization or chromosome architecture, refers to the specific location and spatial arrangement of chromosomes within the nucleus of a eukaryotic cell. This complex process is critical for proper regulation of gene expression, DNA replication, and chromosomal stability during the cell cycle.

Chromosomes are not randomly positioned in the nucleus; instead, they occupy distinct territories that are non-randomly organized with respect to each other. Chromosome positioning is influenced by several factors, including the presence of nuclear bodies, such as the nucleolus and nuclear speckles, as well as by the interactions between chromatin regions and the nuclear lamina.

The spatial organization of chromosomes can have significant consequences for gene regulation, as genes that are located in close proximity to each other may be more likely to interact and influence each other's expression. Chromosome positioning has also been implicated in various diseases, including cancer, where abnormalities in chromosome organization have been associated with changes in gene expression and genomic instability.

Overall, the medical definition of 'chromosome positioning' refers to the complex and dynamic process by which chromosomes are organized within the nucleus of a cell, and how this organization influences various cellular processes and functions.

Cobalt radioisotopes are radioactive forms of the element cobalt, which are used in various medical applications. The most commonly used cobalt radioisotope is Cobalt-60 (Co-60), which has a half-life of 5.27 years.

Co-60 emits gamma rays and beta particles, making it useful for radiation therapy to treat cancer, as well as for sterilizing medical equipment and food irradiation. In radiation therapy, Co-60 is used in teletherapy machines to deliver a focused beam of radiation to tumors, helping to destroy cancer cells while minimizing damage to surrounding healthy tissue.

It's important to note that handling and disposal of cobalt radioisotopes require strict safety measures due to their radioactive nature, as they can pose risks to human health and the environment if not managed properly.

Genetic recombination is the process by which genetic material is exchanged between two similar or identical molecules of DNA during meiosis, resulting in new combinations of genes on each chromosome. This exchange occurs during crossover, where segments of DNA are swapped between non-sister homologous chromatids, creating genetic diversity among the offspring. It is a crucial mechanism for generating genetic variability and facilitating evolutionary change within populations. Additionally, recombination also plays an essential role in DNA repair processes through mechanisms such as homologous recombinational repair (HRR) and non-homologous end joining (NHEJ).

Ploidy is a term used in genetics to describe the number of sets of chromosomes in a cell or an organism. The ploidy level can have important implications for genetic inheritance and expression, as well as for evolutionary processes such as speciation and hybridization.

In most animals, including humans, the normal ploidy level is diploid, meaning that each cell contains two sets of chromosomes - one set inherited from each parent. However, there are also many examples of polyploidy, in which an organism has more than two sets of chromosomes.

Polyploidy can arise through various mechanisms, such as genome duplication or hybridization between different species. In some cases, polyploidy may confer evolutionary advantages, such as increased genetic diversity and adaptability to new environments. However, it can also lead to reproductive isolation and the formation of new species.

In plants, polyploidy is relatively common and has played a significant role in their evolution and diversification. Many crop plants are polyploids, including wheat, cotton, and tobacco. In some cases, artificial induction of polyploidy has been used to create new varieties with desirable traits for agriculture and horticulture.

Overall, ploidy is an important concept in genetics and evolution, with implications for a wide range of biological processes and phenomena.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

Occupational exposure refers to the contact of an individual with potentially harmful chemical, physical, or biological agents as a result of their job or occupation. This can include exposure to hazardous substances such as chemicals, heavy metals, or dusts; physical agents such as noise, radiation, or ergonomic stressors; and biological agents such as viruses, bacteria, or fungi.

Occupational exposure can occur through various routes, including inhalation, skin contact, ingestion, or injection. Prolonged or repeated exposure to these hazards can increase the risk of developing acute or chronic health conditions, such as respiratory diseases, skin disorders, neurological damage, or cancer.

Employers have a legal and ethical responsibility to minimize occupational exposures through the implementation of appropriate control measures, including engineering controls, administrative controls, personal protective equipment, and training programs. Regular monitoring and surveillance of workers' health can also help identify and prevent potential health hazards in the workplace.

A telomere is a region of repetitive DNA sequences found at the end of chromosomes, which protects the genetic data from damage and degradation during cell division. Telomeres naturally shorten as cells divide, and when they become too short, the cell can no longer divide and becomes senescent or dies. This natural process is associated with aging and various age-related diseases. The length of telomeres can also be influenced by various genetic and environmental factors, including stress, diet, and lifestyle.

Deoxyribonucleic acid (DNA) is the genetic material present in the cells of organisms where it is responsible for the storage and transmission of hereditary information. DNA is a long molecule that consists of two strands coiled together to form a double helix. Each strand is made up of a series of four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - that are linked together by phosphate and sugar groups. The sequence of these bases along the length of the molecule encodes genetic information, with A always pairing with T and C always pairing with G. This base-pairing allows for the replication and transcription of DNA, which are essential processes in the functioning and reproduction of all living organisms.

Guaiacol is not a medical term per se, but it is a chemical compound with potential applications in the medical field. Here's a general definition:

Guaiacol (also known as 2-methoxyphenol) is an organic compound that belongs to the class of phenols. It is a colorless or slightly yellow oily liquid with a characteristic smoky odor, and it is soluble in alcohol and ether but only sparingly soluble in water. Guaiacol occurs naturally in the smoke of wood fires and is also found in certain plants, such as guaiacum and creosote bush. It has antimicrobial properties and is used in some medical and industrial applications, including as a precursor for the synthesis of other chemicals.

"Gene rearrangement" is a process that involves the alteration of the order, orientation, or copy number of genes or gene segments within an organism's genome. This natural mechanism plays a crucial role in generating diversity and specificity in the immune system, particularly in vertebrates.

In the context of the immune system, gene rearrangement occurs during the development of B-cells and T-cells, which are responsible for adaptive immunity. The process involves breaking and rejoining DNA segments that encode antigen recognition sites, resulting in a unique combination of gene segments and creating a vast array of possible antigen receptors.

There are two main types of gene rearrangement:

1. V(D)J recombination: This process occurs in both B-cells and T-cells. It involves the recombination of variable (V), diversity (D), and joining (J) gene segments to form a functional antigen receptor gene. In humans, there are multiple copies of V, D, and J segments for each antigen receptor gene, allowing for a vast number of possible combinations.
2. Class switch recombination: This process occurs only in mature B-cells after antigen exposure. It involves the replacement of the constant (C) region of the immunoglobulin heavy chain gene with another C region, resulting in the production of different isotypes of antibodies (IgG, IgA, or IgE) that have distinct effector functions while maintaining the same antigen specificity.

These processes contribute to the generation of a diverse repertoire of antigen receptors, allowing the immune system to recognize and respond effectively to a wide range of pathogens.

X-rays, also known as radiographs, are a type of electromagnetic radiation with higher energy and shorter wavelength than visible light. In medical imaging, X-rays are used to produce images of the body's internal structures, such as bones and organs, by passing the X-rays through the body and capturing the resulting shadows or patterns on a specialized film or digital detector.

The amount of X-ray radiation used is carefully controlled to minimize exposure and ensure patient safety. Different parts of the body absorb X-rays at different rates, allowing for contrast between soft tissues and denser structures like bone. This property makes X-rays an essential tool in diagnosing and monitoring a wide range of medical conditions, including fractures, tumors, infections, and foreign objects within the body.

A base sequence in the context of molecular biology refers to the specific order of nucleotides in a DNA or RNA molecule. In DNA, these nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, uracil (U) takes the place of thymine. The base sequence contains genetic information that is transcribed into RNA and ultimately translated into proteins. It is the exact order of these bases that determines the genetic code and thus the function of the DNA or RNA molecule.

DNA repair is the process by which cells identify and correct damage to the DNA molecules that encode their genome. DNA can be damaged by a variety of internal and external factors, such as radiation, chemicals, and metabolic byproducts. If left unrepaired, this damage can lead to mutations, which may in turn lead to cancer and other diseases.

There are several different mechanisms for repairing DNA damage, including:

1. Base excision repair (BER): This process repairs damage to a single base in the DNA molecule. An enzyme called a glycosylase removes the damaged base, leaving a gap that is then filled in by other enzymes.
2. Nucleotide excision repair (NER): This process repairs more severe damage, such as bulky adducts or crosslinks between the two strands of the DNA molecule. An enzyme cuts out a section of the damaged DNA, and the gap is then filled in by other enzymes.
3. Mismatch repair (MMR): This process repairs errors that occur during DNA replication, such as mismatched bases or small insertions or deletions. Specialized enzymes recognize the error and remove a section of the newly synthesized strand, which is then replaced by new nucleotides.
4. Double-strand break repair (DSBR): This process repairs breaks in both strands of the DNA molecule. There are two main pathways for DSBR: non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ directly rejoins the broken ends, while HR uses a template from a sister chromatid to repair the break.

Overall, DNA repair is a crucial process that helps maintain genome stability and prevent the development of diseases caused by genetic mutations.

Polyploidy is a condition in which a cell or an organism has more than two sets of chromosomes, unlike the typical diploid state where there are only two sets (one from each parent). Polyploidy can occur through various mechanisms such as errors during cell division, fusion of egg and sperm cells that have an abnormal number of chromosomes, or through the reproduction process in plants.

Polyploidy is common in the plant kingdom, where it often leads to larger size, increased biomass, and sometimes hybrid vigor. However, in animals, polyploidy is less common and usually occurs in only certain types of cells or tissues, as most animals require a specific number of chromosomes for normal development and reproduction. In humans, polyploidy is typically not compatible with life and can lead to developmental abnormalities and miscarriage.

Refractive errors are a group of vision conditions that include nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. These conditions occur when the shape of the eye prevents light from focusing directly on the retina, causing blurred or distorted vision.

Myopia is a condition where distant objects appear blurry while close-up objects are clear. This occurs when the eye is too long or the cornea is too curved, causing light to focus in front of the retina instead of directly on it.

Hyperopia, on the other hand, is a condition where close-up objects appear blurry while distant objects are clear. This happens when the eye is too short or the cornea is not curved enough, causing light to focus behind the retina.

Astigmatism is a condition that causes blurred vision at all distances due to an irregularly shaped cornea or lens.

Presbyopia is a natural aging process that affects everyone as they get older, usually around the age of 40. It causes difficulty focusing on close-up objects and can be corrected with reading glasses, bifocals, or progressive lenses.

Refractive errors can be diagnosed through a comprehensive eye exam and are typically corrected with eyeglasses, contact lenses, or refractive surgery such as LASIK.

A centromere is a specialized region found on chromosomes that plays a crucial role in the separation of replicated chromosomes during cell division. It is the point where the sister chromatids (the two copies of a chromosome formed during DNA replication) are joined together. The centromere contains highly repeated DNA sequences and proteins that form a complex structure known as the kinetochore, which serves as an attachment site for microtubules of the mitotic spindle during cell division.

During mitosis or meiosis, the kinetochore facilitates the movement of chromosomes by interacting with the microtubules, allowing for the accurate distribution of genetic material to the daughter cells. Centromeres can vary in their position and structure among different species, ranging from being located near the middle of the chromosome (metacentric) to being positioned closer to one end (acrocentric). The precise location and characteristics of centromeres are essential for proper chromosome segregation and maintenance of genomic stability.

Acute Radiation Syndrome (ARS), also known as radiation sickness, is a set of symptoms that occur within 24 hours after exposure to high levels of ionizing radiation. The severity of the syndrome depends on the dose of radiation received and the duration of exposure. It can be caused by accidental exposure or intentional use in nuclear warfare or terrorist activities.

ARS is typically divided into three categories based on the symptoms and affected organs: hematopoietic, gastrointestinal, and neurovascular.

1. Hematopoietic ARS: This type of ARS affects the bone marrow and results in a decrease in white blood cells, red blood cells, and platelets. Symptoms include fatigue, weakness, fever, infection, and bleeding.
2. Gastrointestinal ARS: This type of ARS affects the gastrointestinal tract and results in nausea, vomiting, diarrhea, abdominal pain, and dehydration.
3. Neurovascular ARS: This is the most severe form of ARS and affects the central nervous system. Symptoms include confusion, disorientation, seizures, coma, and death.

Treatment for ARS includes supportive care such as fluid replacement, blood transfusions, antibiotics, and medications to manage symptoms. In some cases, bone marrow transplantation may be necessary. Prevention measures include limiting exposure to ionizing radiation and using appropriate protective equipment when working with radioactive materials.

Ocular refraction is a medical term that refers to the bending of light as it passes through the optical media of the eye, including the cornea and lens. This process allows the eye to focus light onto the retina, creating a clear image. The refractive power of the eye is determined by the curvature and transparency of these structures.

In a normal eye, light rays are bent or refracted in such a way that they converge at a single point on the retina, producing a sharp and focused image. However, if the curvature of the cornea or lens is too steep or too flat, the light rays may not converge properly, resulting in a refractive error such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism.

Ocular refraction can be measured using a variety of techniques, including retinoscopy, automated refraction, and subjective refraction. These measurements are used to determine the appropriate prescription for corrective lenses such as eyeglasses or contact lenses. In some cases, ocular refractive errors may be corrected surgically through procedures such as LASIK or PRK.

Cesium radioisotopes are different forms of the element cesium that have unstable nuclei and emit radiation. Some commonly used medical cesium radioisotopes include Cs-134 and Cs-137, which are produced from nuclear reactions in nuclear reactors or during nuclear weapons testing.

In medicine, cesium radioisotopes have been used in cancer treatment for the brachytherapy of certain types of tumors. Brachytherapy involves placing a small amount of radioactive material directly into or near the tumor to deliver a high dose of radiation to the cancer cells while minimizing exposure to healthy tissues.

Cesium-137, for example, has been used in the treatment of cervical, endometrial, and prostate cancers. However, due to concerns about potential long-term risks associated with the use of cesium radioisotopes, their use in cancer therapy is becoming less common.

It's important to note that handling and using radioactive materials requires specialized training and equipment to ensure safety and prevent radiation exposure.

A phenotype is the physical or biochemical expression of an organism's genes, or the observable traits and characteristics resulting from the interaction of its genetic constitution (genotype) with environmental factors. These characteristics can include appearance, development, behavior, and resistance to disease, among others. Phenotypes can vary widely, even among individuals with identical genotypes, due to differences in environmental influences, gene expression, and genetic interactions.

Radiation tolerance, in the context of medicine and particularly radiation oncology, refers to the ability of tissues or organs to withstand and recover from exposure to ionizing radiation without experiencing significant damage or loss of function. It is often used to describe the maximum dose of radiation that can be safely delivered to a specific area of the body during radiotherapy treatments.

Radiation tolerance varies depending on the type and location of the tissue or organ. For example, some tissues such as the brain, spinal cord, and lungs have lower radiation tolerance than others like the skin or bone. Factors that can affect radiation tolerance include the total dose of radiation, the fractionation schedule (the number and size of radiation doses), the volume of tissue treated, and the individual patient's overall health and genetic factors.

Assessing radiation tolerance is critical in designing safe and effective radiotherapy plans for cancer patients, as excessive radiation exposure can lead to serious side effects such as radiation-induced injury, fibrosis, or even secondary malignancies.

X chromosome inactivation (XCI) is a process that occurs in females of mammalian species, including humans, to compensate for the difference in gene dosage between the sexes. Females have two X chromosomes, while males have one X and one Y chromosome. To prevent females from having twice as many X-linked genes expressed as males, one of the two X chromosomes in each female cell is randomly inactivated during early embryonic development.

XCI results in the formation of a condensed and transcriptionally inactive structure called a Barr body, which can be observed in the nucleus of female cells. This process ensures that females express similar levels of X-linked genes as males, maintaining a balanced gene dosage. The choice of which X chromosome is inactivated (maternal or paternal) is random and occurs independently in each cell, leading to a mosaic expression pattern of X-linked genes in different cells and tissues of the female body.

Benzene is a colorless, flammable liquid with a sweet odor. It has the molecular formula C6H6 and is composed of six carbon atoms arranged in a ring, bonded to six hydrogen atoms. Benzene is an important industrial solvent and is used as a starting material in the production of various chemicals, including plastics, rubber, resins, and dyes. It is also a natural component of crude oil and gasoline.

In terms of medical relevance, benzene is classified as a human carcinogen by the International Agency for Research on Cancer (IARC) and the Environmental Protection Agency (EPA). Long-term exposure to high levels of benzene can cause various health effects, including anemia, leukemia, and other blood disorders. Occupational exposure to benzene is regulated by the Occupational Safety and Health Administration (OSHA) to protect workers from potential health hazards.

It's important to note that while benzene has legitimate uses in industry, it should be handled with care due to its known health risks. Exposure to benzene can occur through inhalation, skin contact, or accidental ingestion, so appropriate safety measures must be taken when handling this chemical.

Demecolcine is a medication that belongs to the class of drugs called anticholinergics. It is derived from the plant alkaloid colchicine and has been used in medical research for its ability to arrest cells in metaphase, a specific stage of cell division. This property makes demecolcine useful in various laboratory procedures such as chromosome analysis and the production of cultured cell lines.

In clinical settings, demecolcine is not commonly used due to its narrow therapeutic index and potential for toxicity. However, it has been used off-label in some cases to treat conditions associated with uncontrolled cell division, such as certain types of cancer. Its use in these situations is typically reserved for when other treatments have failed or are not well tolerated.

It's important to note that demecolcine should only be administered under the close supervision of a healthcare professional and its use is generally avoided in pregnant women due to the risk of fetal harm.

Meiosis is a type of cell division that results in the formation of four daughter cells, each with half the number of chromosomes as the parent cell. It is a key process in sexual reproduction, where it generates gametes or sex cells (sperm and eggs).

The process of meiosis involves one round of DNA replication followed by two successive nuclear divisions, meiosis I and meiosis II. In meiosis I, homologous chromosomes pair, form chiasma and exchange genetic material through crossing over, then separate from each other. In meiosis II, sister chromatids separate, leading to the formation of four haploid cells. This process ensures genetic diversity in offspring by shuffling and recombining genetic information during the formation of gametes.

Antimutagenic agents are substances that prevent or reduce the frequency of mutations in DNA, which can be caused by various factors such as radiation, chemicals, and free radicals. These agents work by preventing the formation of mutations or by repairing the damage already done to the DNA. They can be found naturally in foods, such as antioxidants, or they can be synthesized in a laboratory. Antimutagenic agents have potential use in cancer prevention and treatment, as well as in reducing the negative effects of environmental mutagens.

Dental disinfectants are antimicrobial agents that are used to inactivate or destroy microorganisms present on dental instruments, equipment, and surfaces in order to prevent the transmission of infectious diseases. These disinfectants are intended to reduce the number of pathogens to a level that is considered safe and poses minimal risk of infection.

Dental disinfectants can be classified based on their spectrum of activity, which ranges from low-level disinfectants that are effective against vegetative bacteria, fungi, and viruses, to high-level disinfectants that also inactivate bacterial spores. The choice of a particular dental disinfectant depends on the intended use, the level of contamination, and the type of microorganisms present.

It is important to follow the manufacturer's instructions for use, including the recommended contact time, concentration, and method of application, to ensure the effectiveness of dental disinfectants. Additionally, proper handling, storage, and disposal of these agents are essential to prevent harm to patients, staff, and the environment.

Human chromosomes are thread-like structures that contain genetic information in the form of DNA and proteins. Each human cell typically contains 46 chromosomes arranged in 23 pairs, except for the sperm and egg cells which contain only 23 chromosomes (one half of the full set).

Chromosome 19 is one of the autosomal chromosomes, meaning it is not a sex chromosome. It is the fifth smallest human chromosome, spanning about 58 million base pairs and representing approximately 1.9% of the total DNA in cells. Chromosome 19 contains more than 1,200 genes that provide instructions for making proteins and RNA molecules involved in various cellular processes.

Chromosome 20 is also an autosomal chromosome, slightly smaller than chromosome 19. It spans about 54 million base pairs and contains around 800 genes that code for proteins and RNA molecules. Chromosome 20 is known to contain several important genes involved in cancer development, such as the tumor suppressor gene TP53.

Together, chromosomes 19 and 20 carry crucial genetic information necessary for normal human growth, development, and health. Abnormalities in these chromosomes can lead to various genetic disorders and diseases.

I'm sorry for any confusion, but "Uranium" is not a medical term. It is a chemical element with the symbol "U" and atomic number 92. Uranium is a dense, silvery-gray metal that is hard and brittle at room temperature. It's primarily used as a fuel in nuclear power plants and in the manufacture of weapons.

While uranium does not have direct medical applications, it does pose potential health risks due to its radioactivity. Exposure to high levels of radiation from uranium can lead to acute radiation sickness, anemia, and an increased risk of cancer. However, under normal circumstances, the general public is not exposed to significant amounts of uranium, so it's not a common health concern.

Chromosomes in insects are thread-like structures that contain genetic material, made up of DNA and proteins, found in the nucleus of a cell. In insects, like other eukaryotes, chromosomes come in pairs, with one set inherited from each parent. They are crucial for the inheritance, storage, and transmission of genetic information from one generation to the next.

Insects typically have a diploid number of chromosomes (2n), which varies among species. The chromosomes are present in the cell's nucleus during interphase as loosely coiled structures called chromatin. During cell division, they condense and become visible under the microscope as distinct, X-shaped structures called metaphase chromosomes.

The insect chromosome set includes autosomal chromosomes, which are identical in appearance and function between males and females, and sex chromosomes, which differ between males and females. In many insects, the males have an XY sex chromosome constitution, while the females have an XX sex chromosome constitution. The sex chromosomes carry genes that determine the sex of the individual.

Insect chromosomes play a vital role in various biological processes, including development, reproduction, and evolution. They are also essential for genetic research and breeding programs in agriculture and medicine.

DNA replication is the biological process by which DNA makes an identical copy of itself during cell division. It is a fundamental mechanism that allows genetic information to be passed down from one generation of cells to the next. During DNA replication, each strand of the double helix serves as a template for the synthesis of a new complementary strand. This results in the creation of two identical DNA molecules. The enzymes responsible for DNA replication include helicase, which unwinds the double helix, and polymerase, which adds nucleotides to the growing strands.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

A DNA probe is a single-stranded DNA molecule that contains a specific sequence of nucleotides, and is labeled with a detectable marker such as a radioisotope or a fluorescent dye. It is used in molecular biology to identify and locate a complementary sequence within a sample of DNA. The probe hybridizes (forms a stable double-stranded structure) with its complementary sequence through base pairing, allowing for the detection and analysis of the target DNA. This technique is widely used in various applications such as genetic testing, diagnosis of infectious diseases, and forensic science.

Genetic models are theoretical frameworks used in genetics to describe and explain the inheritance patterns and genetic architecture of traits, diseases, or phenomena. These models are based on mathematical equations and statistical methods that incorporate information about gene frequencies, modes of inheritance, and the effects of environmental factors. They can be used to predict the probability of certain genetic outcomes, to understand the genetic basis of complex traits, and to inform medical management and treatment decisions.

There are several types of genetic models, including:

1. Mendelian models: These models describe the inheritance patterns of simple genetic traits that follow Mendel's laws of segregation and independent assortment. Examples include autosomal dominant, autosomal recessive, and X-linked inheritance.
2. Complex trait models: These models describe the inheritance patterns of complex traits that are influenced by multiple genes and environmental factors. Examples include heart disease, diabetes, and cancer.
3. Population genetics models: These models describe the distribution and frequency of genetic variants within populations over time. They can be used to study evolutionary processes, such as natural selection and genetic drift.
4. Quantitative genetics models: These models describe the relationship between genetic variation and phenotypic variation in continuous traits, such as height or IQ. They can be used to estimate heritability and to identify quantitative trait loci (QTLs) that contribute to trait variation.
5. Statistical genetics models: These models use statistical methods to analyze genetic data and infer the presence of genetic associations or linkage. They can be used to identify genetic risk factors for diseases or traits.

Overall, genetic models are essential tools in genetics research and medical genetics, as they allow researchers to make predictions about genetic outcomes, test hypotheses about the genetic basis of traits and diseases, and develop strategies for prevention, diagnosis, and treatment.

I'm sorry for any confusion, but "hybrid cells" is not a standard medical term with a widely accepted or specific definition in the field of medicine. The term "hybrid" is used in various scientific and medical contexts to describe combinations or mixtures of different elements, such as hybridoma cells (a type of fusion cell used in research, created by combining a B cell and a tumor cell) or hybridization (in genetics, the process of combining DNA from two different sources).

Without more specific context, it's difficult to provide an accurate medical definition for "hybrid cells." If you could provide more information about the context in which this term was used, I would be happy to help you further!

Gene dosage, in genetic terms, refers to the number of copies of a particular gene present in an organism's genome. Each gene usually has two copies (alleles) in diploid organisms, one inherited from each parent. An increase or decrease in the number of copies of a specific gene can lead to changes in the amount of protein it encodes, which can subsequently affect various biological processes and phenotypic traits.

For example, gene dosage imbalances have been associated with several genetic disorders, such as Down syndrome (trisomy 21), where an individual has three copies of chromosome 21 instead of the typical two copies, leading to developmental delays and intellectual disabilities. Similarly, in certain cases of cancer, gene amplification (an increase in the number of copies of a particular gene) can result in overexpression of oncogenes, contributing to tumor growth and progression.

Genomic instability is a term used in genetics and molecular biology to describe a state of increased susceptibility to genetic changes or mutations in the genome. It can be defined as a condition where the integrity and stability of the genome are compromised, leading to an increased rate of DNA alterations such as point mutations, insertions, deletions, and chromosomal rearrangements.

Genomic instability is a hallmark of cancer cells and can also be observed in various other diseases, including genetic disorders and aging. It can arise due to defects in the DNA repair mechanisms, telomere maintenance, epigenetic regulation, or chromosome segregation during cell division. These defects can result from inherited genetic mutations, acquired somatic mutations, exposure to environmental mutagens, or age-related degenerative changes.

Genomic instability is a significant factor in the development and progression of cancer as it promotes the accumulation of oncogenic mutations that contribute to tumor initiation, growth, and metastasis. Therefore, understanding the mechanisms underlying genomic instability is crucial for developing effective strategies for cancer prevention, diagnosis, and treatment.

The term "DNA, neoplasm" is not a standard medical term or concept. DNA refers to deoxyribonucleic acid, which is the genetic material present in the cells of living organisms. A neoplasm, on the other hand, is a tumor or growth of abnormal tissue that can be benign (non-cancerous) or malignant (cancerous).

In some contexts, "DNA, neoplasm" may refer to genetic alterations found in cancer cells. These genetic changes can include mutations, amplifications, deletions, or rearrangements of DNA sequences that contribute to the development and progression of cancer. Identifying these genetic abnormalities can help doctors diagnose and treat certain types of cancer more effectively.

However, it's important to note that "DNA, neoplasm" is not a term that would typically be used in medical reports or research papers without further clarification. If you have any specific questions about DNA changes in cancer cells or neoplasms, I would recommend consulting with a healthcare professional or conducting further research on the topic.

Chromosomes are thread-like structures located in the nucleus of cells that carry genetic information in the form of genes. A chromosome is made up of one long DNA molecule coiled tightly with proteins called histones to form a compact structure. In humans, there are 23 pairs of chromosomes, for a total of 46 chromosomes in every cell of the body, except for the sperm and egg cells which contain only 23 chromosomes each.

Chromosome structures can be described by their number, shape, size, and banding pattern. The number of chromosomes in a cell is usually constant for a species, but can vary between species. Chromosomes come in different shapes, including rod-shaped, V-shaped, or J-shaped, depending on the position of the centromere, which is the constricted region where the chromatids (the two copies of chromosome) are joined together.

The size of chromosomes also varies, with some being much larger than others. Chromosomes can be classified into several groups based on their size and banding pattern, which is a series of light and dark bands that appear when chromosomes are stained with certain dyes. The banding pattern is unique to each chromosome and can be used to identify specific regions or genes on the chromosome.

Chromosome structures can also be affected by genetic changes, such as mutations, deletions, duplications, inversions, and translocations, which can lead to genetic disorders and diseases. Understanding the structure and function of chromosomes is essential for diagnosing and treating genetic conditions, as well as for advancing our knowledge of genetics and human health.

Mitomycin is an antineoplastic antibiotic derived from Streptomyces caespitosus. It is primarily used in cancer chemotherapy, particularly in the treatment of various carcinomas including gastrointestinal tract malignancies and breast cancer. Mitomycin works by forming cross-links in DNA, thereby inhibiting its replication and transcription, which ultimately leads to cell death.

In addition to its systemic use, mitomycin is also used topically in ophthalmology for the treatment of certain eye conditions such as glaucoma and various ocular surface disorders. The topical application of mitomycin can help reduce scarring and fibrosis by inhibiting the proliferation of fibroblasts.

It's important to note that mitomycin has a narrow therapeutic index, meaning there is only a small range between an effective dose and a toxic one. Therefore, its use should be closely monitored to minimize side effects, which can include myelosuppression, mucositis, alopecia, and potential secondary malignancies.

Spermatozoa are the male reproductive cells, or gametes, that are produced in the testes. They are microscopic, flagellated (tail-equipped) cells that are highly specialized for fertilization. A spermatozoon consists of a head, neck, and tail. The head contains the genetic material within the nucleus, covered by a cap-like structure called the acrosome which contains enzymes to help the sperm penetrate the female's egg (ovum). The long, thin tail propels the sperm forward through fluid, such as semen, enabling its journey towards the egg for fertilization.

Radiometry is the measurement of electromagnetic radiation, including visible light. It quantifies the amount and characteristics of radiant energy in terms of power or intensity, wavelength, direction, and polarization. In medical physics, radiometry is often used to measure therapeutic and diagnostic radiation beams used in various imaging techniques and cancer treatments such as X-rays, gamma rays, and ultraviolet or infrared light. Radiometric measurements are essential for ensuring the safe and effective use of these medical technologies.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

The cell cycle is a series of events that take place in a cell leading to its division and duplication. It consists of four main phases: G1 phase, S phase, G2 phase, and M phase.

During the G1 phase, the cell grows in size and synthesizes mRNA and proteins in preparation for DNA replication. In the S phase, the cell's DNA is copied, resulting in two complete sets of chromosomes. During the G2 phase, the cell continues to grow and produces more proteins and organelles necessary for cell division.

The M phase is the final stage of the cell cycle and consists of mitosis (nuclear division) and cytokinesis (cytoplasmic division). Mitosis results in two genetically identical daughter nuclei, while cytokinesis divides the cytoplasm and creates two separate daughter cells.

The cell cycle is regulated by various checkpoints that ensure the proper completion of each phase before progressing to the next. These checkpoints help prevent errors in DNA replication and division, which can lead to mutations and cancer.

Human chromosome pair 3 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and together they contain the genetic material that is inherited from both parents. Chromosomes are made up of DNA, which contains the instructions for the development and function of all living organisms.

Human chromosomes are numbered from 1 to 22, with an additional two sex chromosomes (X and Y) that determine biological sex. Chromosome pair 3 is one of the autosomal pairs, meaning it contains genes that are not related to sex determination. Each member of chromosome pair 3 is identical in size and shape and contains a single long DNA molecule that is coiled tightly around histone proteins to form a compact structure.

Chromosome pair 3 is associated with several genetic disorders, including Waardenburg syndrome, which affects pigmentation and hearing; Marfan syndrome, which affects the connective tissue; and some forms of retinoblastoma, a rare eye cancer that typically affects young children.

Industrial fungicides are antimicrobial agents used to prevent, destroy, or inhibit the growth of fungi and their spores in industrial settings. These can include uses in manufacturing processes, packaging materials, textiles, paints, and other industrial products. They work by interfering with the cellular structure or metabolic processes of fungi, thereby preventing their growth or reproduction. Examples of industrial fungicides include:

* Sodium hypochlorite (bleach)
* Formaldehyde
* Glutaraldehyde
* Quaternary ammonium compounds
* Peracetic acid
* Chlorhexidine
* Iodophors

It's important to note that some of these fungicides can be harmful or toxic to humans and other organisms, so they must be used with caution and in accordance with safety guidelines.

Microsatellite repeats, also known as short tandem repeats (STRs), are repetitive DNA sequences made up of units of 1-6 base pairs that are repeated in a head-to-tail manner. These repeats are spread throughout the human genome and are highly polymorphic, meaning they can have different numbers of repeat units in different individuals.

Microsatellites are useful as genetic markers because of their high degree of variability. They are commonly used in forensic science to identify individuals, in genealogy to trace ancestry, and in medical research to study genetic diseases and disorders. Mutations in microsatellite repeats have been associated with various neurological conditions, including Huntington's disease and fragile X syndrome.

Crossing over, genetic is a process that occurs during meiosis, where homologous chromosomes exchange genetic material with each other. It is a crucial mechanism for generating genetic diversity in sexually reproducing organisms.

Here's a more detailed explanation:

During meiosis, homologous chromosomes pair up and align closely with each other. At this point, sections of the chromosomes can break off and reattach to the corresponding section on the homologous chromosome. This exchange of genetic material is called crossing over or genetic recombination.

The result of crossing over is that the two resulting chromosomes are no longer identical to each other or to the original chromosomes. Instead, they contain a unique combination of genetic material from both parents. Crossing over can lead to new combinations of alleles (different forms of the same gene) and can increase genetic diversity in the population.

Crossing over is a random process, so the location and frequency of crossover events vary between individuals and between chromosomes. The number and position of crossovers can affect the likelihood that certain genes will be inherited together or separated, which is an important consideration in genetic mapping and breeding studies.

DNA-binding proteins are a type of protein that have the ability to bind to DNA (deoxyribonucleic acid), the genetic material of organisms. These proteins play crucial roles in various biological processes, such as regulation of gene expression, DNA replication, repair and recombination.

The binding of DNA-binding proteins to specific DNA sequences is mediated by non-covalent interactions, including electrostatic, hydrogen bonding, and van der Waals forces. The specificity of binding is determined by the recognition of particular nucleotide sequences or structural features of the DNA molecule.

DNA-binding proteins can be classified into several categories based on their structure and function, such as transcription factors, histones, and restriction enzymes. Transcription factors are a major class of DNA-binding proteins that regulate gene expression by binding to specific DNA sequences in the promoter region of genes and recruiting other proteins to modulate transcription. Histones are DNA-binding proteins that package DNA into nucleosomes, the basic unit of chromatin structure. Restriction enzymes are DNA-binding proteins that recognize and cleave specific DNA sequences, and are widely used in molecular biology research and biotechnology applications.

Bone marrow is the spongy tissue found inside certain bones in the body, such as the hips, thighs, and vertebrae. It is responsible for producing blood-forming cells, including red blood cells, white blood cells, and platelets. There are two types of bone marrow: red marrow, which is involved in blood cell production, and yellow marrow, which contains fatty tissue.

Red bone marrow contains hematopoietic stem cells, which can differentiate into various types of blood cells. These stem cells continuously divide and mature to produce new blood cells that are released into the circulation. Red blood cells carry oxygen throughout the body, white blood cells help fight infections, and platelets play a crucial role in blood clotting.

Bone marrow also serves as a site for immune cell development and maturation. It contains various types of immune cells, such as lymphocytes, macrophages, and dendritic cells, which help protect the body against infections and diseases.

Abnormalities in bone marrow function can lead to several medical conditions, including anemia, leukopenia, thrombocytopenia, and various types of cancer, such as leukemia and multiple myeloma. Bone marrow aspiration and biopsy are common diagnostic procedures used to evaluate bone marrow health and function.

Comparative genomic hybridization (CGH) is a molecular cytogenetic technique used to detect and measure changes in the DNA content of an individual's genome. It is a type of microarray-based analysis that compares the DNA of two samples, typically a test sample and a reference sample, to identify copy number variations (CNVs), including gains or losses of genetic material.

In CGH, the DNA from both samples is labeled with different fluorescent dyes, typically one sample with a green fluorophore and the other with a red fluorophore. The labeled DNAs are then co-hybridized to a microarray, which contains thousands of DNA probes representing specific genomic regions. The intensity of each spot on the array reflects the amount of DNA from each sample that has hybridized to the probe.

By comparing the ratio of green to red fluorescence intensities for each probe, CGH can detect gains or losses of genetic material in the test sample relative to the reference sample. A ratio of 1 indicates no difference in copy number between the two samples, while a ratio greater than 1 suggests a gain of genetic material, and a ratio less than 1 suggests a loss.

CGH is a powerful tool for detecting genomic imbalances associated with various genetic disorders, including cancer, developmental delay, intellectual disability, and congenital abnormalities. It can also be used to study the genomics of organisms in evolutionary biology and ecological studies.

I must clarify that the term "pedigree" is not typically used in medical definitions. Instead, it is often employed in genetics and breeding, where it refers to the recorded ancestry of an individual or a family, tracing the inheritance of specific traits or diseases. In human genetics, a pedigree can help illustrate the pattern of genetic inheritance in families over multiple generations. However, it is not a medical term with a specific clinical definition.

"Genetic crosses" refer to the breeding of individuals with different genetic characteristics to produce offspring with specific combinations of traits. This process is commonly used in genetics research to study the inheritance patterns and function of specific genes.

There are several types of genetic crosses, including:

1. Monohybrid cross: A cross between two individuals that differ in the expression of a single gene or trait.
2. Dihybrid cross: A cross between two individuals that differ in the expression of two genes or traits.
3. Backcross: A cross between an individual from a hybrid population and one of its parental lines.
4. Testcross: A cross between an individual with unknown genotype and a homozygous recessive individual.
5. Reciprocal cross: A cross in which the male and female parents are reversed to determine if there is any effect of sex on the expression of the trait.

These genetic crosses help researchers to understand the mode of inheritance, linkage, recombination, and other genetic phenomena.

'Drosophila melanogaster' is the scientific name for a species of fruit fly that is commonly used as a model organism in various fields of biological research, including genetics, developmental biology, and evolutionary biology. Its small size, short generation time, large number of offspring, and ease of cultivation make it an ideal subject for laboratory studies. The fruit fly's genome has been fully sequenced, and many of its genes have counterparts in the human genome, which facilitates the understanding of genetic mechanisms and their role in human health and disease.

Here is a brief medical definition:

Drosophila melanogaster (droh-suh-fih-luh meh-lon-guh-ster): A species of fruit fly used extensively as a model organism in genetic, developmental, and evolutionary research. Its genome has been sequenced, revealing many genes with human counterparts, making it valuable for understanding genetic mechanisms and their role in human health and disease.

Leukemia, myeloid is a type of cancer that originates in the bone marrow, where blood cells are produced. Myeloid leukemia affects the myeloid cells, which include red blood cells, platelets, and most types of white blood cells. In this condition, the bone marrow produces abnormal myeloid cells that do not mature properly and accumulate in the bone marrow and blood. These abnormal cells hinder the production of normal blood cells, leading to various symptoms such as anemia, fatigue, increased risk of infections, and easy bruising or bleeding.

There are several types of myeloid leukemias, including acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). AML progresses rapidly and requires immediate treatment, while CML tends to progress more slowly. The exact causes of myeloid leukemia are not fully understood, but risk factors include exposure to radiation or certain chemicals, smoking, genetic disorders, and a history of chemotherapy or other cancer treatments.

Cell survival refers to the ability of a cell to continue living and functioning normally, despite being exposed to potentially harmful conditions or treatments. This can include exposure to toxins, radiation, chemotherapeutic drugs, or other stressors that can damage cells or interfere with their normal processes.

In scientific research, measures of cell survival are often used to evaluate the effectiveness of various therapies or treatments. For example, researchers may expose cells to a particular drug or treatment and then measure the percentage of cells that survive to assess its potential therapeutic value. Similarly, in toxicology studies, measures of cell survival can help to determine the safety of various chemicals or substances.

It's important to note that cell survival is not the same as cell proliferation, which refers to the ability of cells to divide and multiply. While some treatments may promote cell survival, they may also inhibit cell proliferation, making them useful for treating diseases such as cancer. Conversely, other treatments may be designed to specifically target and kill cancer cells, even if it means sacrificing some healthy cells in the process.

A LOD (Logarithm of Odds) score is not a medical term per se, but rather a statistical concept that is used in genetic research and linkage analysis to determine the likelihood of a gene or genetic marker being linked to a particular disease or trait. The LOD score compares the odds of observing the pattern of inheritance of a genetic marker in a family if the marker is linked to the disease, versus the odds if the marker is not linked. A LOD score of 3 or higher is generally considered evidence for linkage, while a score of -2 or lower is considered evidence against linkage.

An allele is a variant form of a gene that is located at a specific position on a specific chromosome. Alleles are alternative forms of the same gene that arise by mutation and are found at the same locus or position on homologous chromosomes.

Each person typically inherits two copies of each gene, one from each parent. If the two alleles are identical, a person is said to be homozygous for that trait. If the alleles are different, the person is heterozygous.

For example, the ABO blood group system has three alleles, A, B, and O, which determine a person's blood type. If a person inherits two A alleles, they will have type A blood; if they inherit one A and one B allele, they will have type AB blood; if they inherit two B alleles, they will have type B blood; and if they inherit two O alleles, they will have type O blood.

Alleles can also influence traits such as eye color, hair color, height, and other physical characteristics. Some alleles are dominant, meaning that only one copy of the allele is needed to express the trait, while others are recessive, meaning that two copies of the allele are needed to express the trait.

Cell cycle proteins are a group of regulatory proteins that control the progression of the cell cycle, which is the series of events that take place in a eukaryotic cell leading to its division and duplication. These proteins can be classified into several categories based on their functions during different stages of the cell cycle.

The major groups of cell cycle proteins include:

1. Cyclin-dependent kinases (CDKs): CDKs are serine/threonine protein kinases that regulate key transitions in the cell cycle. They require binding to a regulatory subunit called cyclin to become active. Different CDK-cyclin complexes are activated at different stages of the cell cycle.
2. Cyclins: Cyclins are a family of regulatory proteins that bind and activate CDKs. Their levels fluctuate throughout the cell cycle, with specific cyclins expressed during particular phases. For example, cyclin D is important for the G1 to S phase transition, while cyclin B is required for the G2 to M phase transition.
3. CDK inhibitors (CKIs): CKIs are regulatory proteins that bind to and inhibit CDKs, thereby preventing their activation. CKIs can be divided into two main families: the INK4 family and the Cip/Kip family. INK4 family members specifically inhibit CDK4 and CDK6, while Cip/Kip family members inhibit a broader range of CDKs.
4. Anaphase-promoting complex/cyclosome (APC/C): APC/C is an E3 ubiquitin ligase that targets specific proteins for degradation by the 26S proteasome. During the cell cycle, APC/C regulates the metaphase to anaphase transition and the exit from mitosis by targeting securin and cyclin B for degradation.
5. Other regulatory proteins: Several other proteins play crucial roles in regulating the cell cycle, such as p53, a transcription factor that responds to DNA damage and arrests the cell cycle, and the polo-like kinases (PLKs), which are involved in various aspects of mitosis.

Overall, cell cycle proteins work together to ensure the proper progression of the cell cycle, maintain genomic stability, and prevent uncontrolled cell growth, which can lead to cancer.

Ocular accommodation is the process by which the eye changes optical power to maintain a clear image or focus on an object as its distance varies. This is primarily achieved by the lens of the eye changing shape through the action of the ciliary muscles inside the eye. When you look at something far away, the lens becomes flatter, and when you look at something close up, the lens thickens. This ability to adjust focus allows for clear vision at different distances.

Environmental exposure refers to the contact of an individual with any chemical, physical, or biological agent in the environment that can cause a harmful effect on health. These exposures can occur through various pathways such as inhalation, ingestion, or skin contact. Examples of environmental exposures include air pollution, water contamination, occupational chemicals, and allergens. The duration and level of exposure, as well as the susceptibility of the individual, can all contribute to the risk of developing an adverse health effect.

Astigmatism is a common eye condition that occurs when the cornea or lens has an irregular shape, causing blurred or distorted vision. The cornea and lens are typically smooth and curved uniformly in all directions, allowing light to focus clearly on the retina. However, if the cornea or lens is not smoothly curved and has a steeper curve in one direction than the other, it causes light to focus unevenly on the retina, leading to astigmatism.

Astigmatism can cause blurred vision at all distances, as well as eye strain, headaches, and fatigue. It is often present from birth and can be hereditary, but it can also develop later in life due to eye injuries or surgery. Astigmatism can be corrected with glasses, contact lenses, or refractive surgery such as LASIK.

Fibroblasts are specialized cells that play a critical role in the body's immune response and wound healing process. They are responsible for producing and maintaining the extracellular matrix (ECM), which is the non-cellular component present within all tissues and organs, providing structural support and biochemical signals for surrounding cells.

Fibroblasts produce various ECM proteins such as collagens, elastin, fibronectin, and laminins, forming a complex network of fibers that give tissues their strength and flexibility. They also help in the regulation of tissue homeostasis by controlling the turnover of ECM components through the process of remodeling.

In response to injury or infection, fibroblasts become activated and start to proliferate rapidly, migrating towards the site of damage. Here, they participate in the inflammatory response, releasing cytokines and chemokines that attract immune cells to the area. Additionally, they deposit new ECM components to help repair the damaged tissue and restore its functionality.

Dysregulation of fibroblast activity has been implicated in several pathological conditions, including fibrosis (excessive scarring), cancer (where they can contribute to tumor growth and progression), and autoimmune diseases (such as rheumatoid arthritis).

Molecular cloning is a laboratory technique used to create multiple copies of a specific DNA sequence. This process involves several steps:

1. Isolation: The first step in molecular cloning is to isolate the DNA sequence of interest from the rest of the genomic DNA. This can be done using various methods such as PCR (polymerase chain reaction), restriction enzymes, or hybridization.
2. Vector construction: Once the DNA sequence of interest has been isolated, it must be inserted into a vector, which is a small circular DNA molecule that can replicate independently in a host cell. Common vectors used in molecular cloning include plasmids and phages.
3. Transformation: The constructed vector is then introduced into a host cell, usually a bacterial or yeast cell, through a process called transformation. This can be done using various methods such as electroporation or chemical transformation.
4. Selection: After transformation, the host cells are grown in selective media that allow only those cells containing the vector to grow. This ensures that the DNA sequence of interest has been successfully cloned into the vector.
5. Amplification: Once the host cells have been selected, they can be grown in large quantities to amplify the number of copies of the cloned DNA sequence.

Molecular cloning is a powerful tool in molecular biology and has numerous applications, including the production of recombinant proteins, gene therapy, functional analysis of genes, and genetic engineering.

Neoplastic cell transformation is a process in which a normal cell undergoes genetic alterations that cause it to become cancerous or malignant. This process involves changes in the cell's DNA that result in uncontrolled cell growth and division, loss of contact inhibition, and the ability to invade surrounding tissues and metastasize (spread) to other parts of the body.

Neoplastic transformation can occur as a result of various factors, including genetic mutations, exposure to carcinogens, viral infections, chronic inflammation, and aging. These changes can lead to the activation of oncogenes or the inactivation of tumor suppressor genes, which regulate cell growth and division.

The transformation of normal cells into cancerous cells is a complex and multi-step process that involves multiple genetic and epigenetic alterations. It is characterized by several hallmarks, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabling replicative immortality, induction of angiogenesis, activation of invasion and metastasis, reprogramming of energy metabolism, and evading immune destruction.

Neoplastic cell transformation is a fundamental concept in cancer biology and is critical for understanding the molecular mechanisms underlying cancer development and progression. It also has important implications for cancer diagnosis, prognosis, and treatment, as identifying the specific genetic alterations that underlie neoplastic transformation can help guide targeted therapies and personalized medicine approaches.

Chromosome fragility refers to the susceptibility of specific regions on chromosomes to break or become unstable during cell division. These fragile sites are prone to forming gaps or breaks in the chromosome structure, which can lead to genetic rearrangements, including deletions, duplications, or translocations.

Chromosome fragility is often associated with certain genetic disorders and syndromes. For example, the most common fragile site in human chromosomes is FRAXA, located on the X chromosome, which is linked to Fragile X Syndrome, a leading cause of inherited intellectual disability and autism.

Environmental factors such as exposure to chemicals or radiation can also increase chromosome fragility, leading to an increased risk of genetic mutations and diseases.

A karyotype is a method used in genetics to describe the number and visual appearance of chromosomes in the nucleus of a cell. It includes the arrangement of the chromosomes by length, position of the centromeres, and banding pattern. A karyotype is often represented as a photograph or image of an individual's chromosomes, arranged in pairs from largest to smallest, that has been stained to show the bands of DNA. This information can be used to identify genetic abnormalities, such as extra or missing chromosomes, or structural changes, such as deletions, duplications, or translocations. A karyotype is typically obtained by culturing cells from a sample of blood or tissue, then arresting the cell division at metaphase and staining the chromosomes to make them visible for analysis.

Pesticides are substances or mixtures of substances intended for preventing, destroying, or repelling pests. Pests can be insects, rodents, fungi, weeds, or other organisms that can cause damage to crops, animals, or humans and their living conditions. The term "pesticide" includes all of the following: insecticides, herbicides, fungicides, rodenticides, bactericides, and various other substances used to control pests.

It is important to note that while pesticides are designed to be toxic to the target pests, they can also pose risks to non-target organisms, including humans, if not used properly. Therefore, it is essential to follow all label instructions and safety precautions when handling and applying pesticides.

A human genome is the complete set of genetic information contained within the 23 pairs of chromosomes found in the nucleus of most human cells. It includes all of the genes, which are segments of DNA that contain the instructions for making proteins, as well as non-coding regions of DNA that regulate gene expression and provide structural support to the chromosomes.

The human genome contains approximately 3 billion base pairs of DNA and is estimated to contain around 20,000-25,000 protein-coding genes. The sequencing of the human genome was completed in 2003 as part of the Human Genome Project, which has had a profound impact on our understanding of human biology, disease, and evolution.

Ataxia telangiectasia is a rare, inherited genetic disorder that affects the nervous system, immune system, and overall development. The condition is characterized by progressive difficulty with coordination and balance (ataxia), as well as the development of small, dilated blood vessels (telangiectasias) on the skin and eyes.

The underlying cause of ataxia telangiectasia is a mutation in the ATM gene, which provides instructions for making a protein that plays a critical role in DNA repair and maintaining genetic stability. When this gene is mutated, cells are unable to properly repair damaged DNA, leading to an increased risk of cancer and other health problems.

Individuals with ataxia telangiectasia typically begin to show symptoms during early childhood, with progressive difficulties in coordination and balance, slurred speech, and recurrent respiratory infections due to weakened immune function. Over time, these symptoms can worsen, leading to significant disability and reduced life expectancy.

There is currently no cure for ataxia telangiectasia, and treatment is focused on managing the symptoms and complications of the condition. This may include physical therapy, speech therapy, and medications to help control infections and other health problems.

Nondisjunction is a genetic term that refers to the failure of homologous chromosomes or sister chromatids to properly separate during cell division, resulting in an abnormal number of chromosomes in the daughter cells. This can occur during either mitosis (resulting in somatic mutations) or meiosis (leading to gametes with an incorrect number of chromosomes).

In humans, nondisjunction of chromosome 21 during meiosis is the most common cause of Down syndrome, resulting in three copies of chromosome 21 (trisomy 21) in the affected individual. Nondisjunction can also result in other aneuploidies, such as Turner syndrome (X monosomy), Klinefelter syndrome (XXY), and Edwards syndrome (trisomy 18).

Nondisjunction is typically a random event, although maternal age has been identified as a risk factor for nondisjunction during meiosis. In some cases, structural chromosomal abnormalities or genetic factors may predispose an individual to nondisjunction events.

Monosomy is a type of chromosomal abnormality in which there is only one copy of a particular chromosome instead of the usual pair in a diploid cell. In monosomy, an individual has one less chromosome than the normal diploid number (46 chromosomes) due to the absence of one member of a chromosome pair. This condition arises from the loss of one chromosome in an egg or sperm during gamete formation or at conception.

Examples of monosomy include Turner syndrome, which is characterized by the presence of only one X chromosome (45,X), and Cri du Chat syndrome, which results from a deletion of a portion of the short arm of chromosome 5 (46,del(5)(p15.2)). Monosomy can lead to developmental abnormalities, physical defects, intellectual disabilities, and various health issues depending on the chromosome involved.

Chromosome duplication is a genetic alteration where a segment of a chromosome or the entire chromosome is present in an extra copy. This results in an additional portion of genetic material, leading to an abnormal number of genes. In humans, chromosomes typically occur in pairs (23 pairs for a total of 46 chromosomes), and any deviation from this normal number can cause genetic disorders or developmental abnormalities.

Duplication can occur in various ways:

1. Duplication of a chromosome segment: A specific region of a chromosome is repeated, leading to an extra copy of the genes present in that area. This type of duplication may not always cause noticeable effects, depending on the size and location of the duplicated segment. However, if the duplicated region contains important genes or growth regulatory elements, it can lead to genetic disorders or developmental abnormalities.
2. Duplication of a whole chromosome: An entire chromosome is present in an extra copy, leading to 3 copies instead of the typical 2 copies (one from each parent). This condition is called trisomy and can result in various genetic disorders, depending on which chromosome is duplicated. For example, Trisomy 21 or Down syndrome occurs when there are three copies of chromosome 21.
3. Mosaicism: When an individual has some cells with a normal number of chromosomes and others with the extra copy, it is called mosaicism. The severity of symptoms depends on the proportion of cells carrying the duplication and the specific genes involved in the duplicated region.

Chromosome duplications can occur spontaneously during cell division or may be inherited from a parent. They are often detected through prenatal testing, such as amniocentesis or chorionic villus sampling (CVS), or through genetic testing for individuals with developmental delays, intellectual disabilities, or birth defects.

Loss of Heterozygosity (LOH) is a term used in genetics to describe the loss of one copy of a gene or a segment of a chromosome, where there was previously a pair of different genes or chromosomal segments (heterozygous). This can occur due to various genetic events such as mutation, deletion, or mitotic recombination.

LOH is often associated with the development of cancer, as it can lead to the loss of tumor suppressor genes, which normally help to regulate cell growth and division. When both copies of a tumor suppressor gene are lost or inactivated, it can result in uncontrolled cell growth and the formation of a tumor.

In medical terms, LOH is used as a biomarker for cancer susceptibility, progression, and prognosis. It can also be used to identify individuals who may be at increased risk for certain types of cancer, or to monitor patients for signs of cancer recurrence.

DNA Sequence Analysis is the systematic determination of the order of nucleotides in a DNA molecule. It is a critical component of modern molecular biology, genetics, and genetic engineering. The process involves determining the exact order of the four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - in a DNA molecule or fragment. This information is used in various applications such as identifying gene mutations, studying evolutionary relationships, developing molecular markers for breeding, and diagnosing genetic diseases.

The process of DNA Sequence Analysis typically involves several steps, including DNA extraction, PCR amplification (if necessary), purification, sequencing reaction, and electrophoresis. The resulting data is then analyzed using specialized software to determine the exact sequence of nucleotides.

In recent years, high-throughput DNA sequencing technologies have revolutionized the field of genomics, enabling the rapid and cost-effective sequencing of entire genomes. This has led to an explosion of genomic data and new insights into the genetic basis of many diseases and traits.

Pregnancy is a physiological state or condition where a fertilized egg (zygote) successfully implants and grows in the uterus of a woman, leading to the development of an embryo and finally a fetus. This process typically spans approximately 40 weeks, divided into three trimesters, and culminates in childbirth. Throughout this period, numerous hormonal and physical changes occur to support the growing offspring, including uterine enlargement, breast development, and various maternal adaptations to ensure the fetus's optimal growth and well-being.

Genotype, in genetics, refers to the complete heritable genetic makeup of an individual organism, including all of its genes. It is the set of instructions contained in an organism's DNA for the development and function of that organism. The genotype is the basis for an individual's inherited traits, and it can be contrasted with an individual's phenotype, which refers to the observable physical or biochemical characteristics of an organism that result from the expression of its genes in combination with environmental influences.

It is important to note that an individual's genotype is not necessarily identical to their genetic sequence. Some genes have multiple forms called alleles, and an individual may inherit different alleles for a given gene from each parent. The combination of alleles that an individual inherits for a particular gene is known as their genotype for that gene.

Understanding an individual's genotype can provide important information about their susceptibility to certain diseases, their response to drugs and other treatments, and their risk of passing on inherited genetic disorders to their offspring.

Spontaneous abortion, also known as miscarriage, is the unintentional expulsion of a nonviable fetus from the uterus before the 20th week of gestation. It is a common complication of early pregnancy, with most miscarriages occurring during the first trimester. Spontaneous abortion can have various causes, including chromosomal abnormalities, maternal health conditions, infections, hormonal imbalances, and structural issues of the uterus or cervix. In many cases, the exact cause may remain unknown.

The symptoms of spontaneous abortion can vary but often include vaginal bleeding, which may range from light spotting to heavy bleeding; abdominal pain or cramping; and the passing of tissue or clots from the vagina. While some miscarriages occur suddenly and are immediately noticeable, others may progress slowly over several days or even weeks.

In medical practice, healthcare providers often use specific terminology to describe different stages and types of spontaneous abortion. For example:

* Threatened abortion: Vaginal bleeding during early pregnancy, but the cervix remains closed, and there is no evidence of fetal demise or passing of tissue.
* Inevitable abortion: Vaginal bleeding with an open cervix, indicating that a miscarriage is imminent or already in progress.
* Incomplete abortion: The expulsion of some but not all products of conception from the uterus, requiring medical intervention to remove any remaining tissue.
* Complete abortion: The successful passage of all products of conception from the uterus, often confirmed through an ultrasound or pelvic examination.
* Missed abortion: The death of a fetus in the uterus without any expulsion of the products of conception, which may be discovered during routine prenatal care.
* Septic abortion: A rare and life-threatening complication of spontaneous abortion characterized by infection of the products of conception and the surrounding tissues, requiring prompt medical attention and antibiotic treatment.

Healthcare providers typically monitor patients who experience a spontaneous abortion to ensure that all products of conception have been expelled and that there are no complications, such as infection or excessive bleeding. In some cases, medication or surgical intervention may be necessary to remove any remaining tissue or address other issues related to the miscarriage. Counseling and support services are often available for individuals and couples who experience a spontaneous abortion, as they may face emotional challenges and concerns about future pregnancies.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

A mammalian embryo is the developing offspring of a mammal, from the time of implantation of the fertilized egg (blastocyst) in the uterus until the end of the eighth week of gestation. During this period, the embryo undergoes rapid cell division and organ differentiation to form a complex structure with all the major organs and systems in place. This stage is followed by fetal development, which continues until birth. The study of mammalian embryos is important for understanding human development, evolution, and reproductive biology.

Polymerase Chain Reaction (PCR) is a laboratory technique used to amplify specific regions of DNA. It enables the production of thousands to millions of copies of a particular DNA sequence in a rapid and efficient manner, making it an essential tool in various fields such as molecular biology, medical diagnostics, forensic science, and research.

The PCR process involves repeated cycles of heating and cooling to separate the DNA strands, allow primers (short sequences of single-stranded DNA) to attach to the target regions, and extend these primers using an enzyme called Taq polymerase, resulting in the exponential amplification of the desired DNA segment.

In a medical context, PCR is often used for detecting and quantifying specific pathogens (viruses, bacteria, fungi, or parasites) in clinical samples, identifying genetic mutations or polymorphisms associated with diseases, monitoring disease progression, and evaluating treatment effectiveness.

A pupil, in medical terms, refers to the circular opening in the center of the iris (the colored part of the eye) that allows light to enter and reach the retina. The size of the pupil can change involuntarily in response to light intensity and emotional state, as well as voluntarily through certain eye exercises or with the use of eye drops. Pupillary reactions are important in clinical examinations as they can provide valuable information about the nervous system's functioning, particularly the brainstem and cranial nerves II and III.

Neoplasms are abnormal growths of cells or tissues in the body that serve no physiological function. They can be benign (non-cancerous) or malignant (cancerous). Benign neoplasms are typically slow growing and do not spread to other parts of the body, while malignant neoplasms are aggressive, invasive, and can metastasize to distant sites.

Neoplasms occur when there is a dysregulation in the normal process of cell division and differentiation, leading to uncontrolled growth and accumulation of cells. This can result from genetic mutations or other factors such as viral infections, environmental exposures, or hormonal imbalances.

Neoplasms can develop in any organ or tissue of the body and can cause various symptoms depending on their size, location, and type. Treatment options for neoplasms include surgery, radiation therapy, chemotherapy, immunotherapy, and targeted therapy, among others.

Diploidy is a term used in genetics to describe the state of having two sets of chromosomes in each cell. In diploid organisms, one set of chromosomes is inherited from each parent, resulting in a total of 2 sets of chromosomes.

In humans, for example, most cells are diploid and contain 46 chromosomes arranged in 23 pairs. This includes 22 pairs of autosomal chromosomes and one pair of sex chromosomes (XX in females or XY in males). Diploidy is a characteristic feature of many complex organisms, including animals, plants, and fungi.

Diploid cells can undergo a process called meiosis, which results in the formation of haploid cells that contain only one set of chromosomes. These haploid cells can then combine with other haploid cells during fertilization to form a new diploid organism.

Abnormalities in diploidy can lead to genetic disorders, such as Down syndrome, which occurs when an individual has three copies of chromosome 21 instead of the typical two. This extra copy of the chromosome can result in developmental delays and intellectual disabilities.

Artificial human chromosomes are artificially constructed chromosomes that contain human genetic material. They are created in a laboratory setting and can be used for various research purposes, such as studying the function of specific genes or creating cell lines with modified genetic characteristics. Artificial human chromosomes are typically created by combining pieces of human DNA with a scaffold made of non-human DNA, which provides structural support and allows the artificial chromosome to behave like a natural human chromosome. These chromosomes can then be introduced into human cells through various methods, such as microcell-mediated chromosome transfer or direct injection into the cell nucleus. It is important to note that artificial human chromosomes are not present in nature and are solely created for research purposes.

Kinetochores are specialized protein structures that form on the centromere region of a chromosome. They play a crucial role in the process of cell division, specifically during mitosis and meiosis. The primary function of kinetochores is to connect the chromosomes to the microtubules of the spindle apparatus, which is responsible for separating the sister chromatids during cell division. Through this connection, kinetochores facilitate the movement of chromosomes towards opposite poles of the cell during anaphase, ensuring equal distribution of genetic material to each resulting daughter cell.

The spindle apparatus is a microtubule-based structure that plays a crucial role in the process of cell division, specifically during mitosis and meiosis. It consists of three main components:

1. The spindle poles: These are organized structures composed of microtubules and associated proteins that serve as the anchoring points for the spindle fibers. In animal cells, these poles are typically formed by centrosomes, while in plant cells, they form around nucleation sites called microtubule-organizing centers (MTOCs).
2. The spindle fibers: These are dynamic arrays of microtubules that extend between the two spindle poles. They can be categorized into three types: kinetochore fibers, which connect to the kinetochores on chromosomes; astral fibers, which radiate from the spindle poles and help position the spindle within the cell; and interpolar fibers, which lie between the two spindle poles and contribute to their separation during anaphase.
3. Regulatory proteins: Various motor proteins, such as dynein and kinesin, as well as non-motor proteins like tubulin and septins, are involved in the assembly, maintenance, and dynamics of the spindle apparatus. These proteins help to generate forces that move chromosomes, position the spindle, and ultimately segregate genetic material between two daughter cells during cell division.

The spindle apparatus is essential for ensuring accurate chromosome separation and maintaining genomic stability during cell division. Dysfunction of the spindle apparatus can lead to various abnormalities, including aneuploidy (abnormal number of chromosomes) and chromosomal instability, which have been implicated in several diseases, such as cancer and developmental disorders.

Southern blotting is a type of membrane-based blotting technique that is used in molecular biology to detect and locate specific DNA sequences within a DNA sample. This technique is named after its inventor, Edward M. Southern.

In Southern blotting, the DNA sample is first digested with one or more restriction enzymes, which cut the DNA at specific recognition sites. The resulting DNA fragments are then separated based on their size by gel electrophoresis. After separation, the DNA fragments are denatured to convert them into single-stranded DNA and transferred onto a nitrocellulose or nylon membrane.

Once the DNA has been transferred to the membrane, it is hybridized with a labeled probe that is complementary to the sequence of interest. The probe can be labeled with radioactive isotopes, fluorescent dyes, or chemiluminescent compounds. After hybridization, the membrane is washed to remove any unbound probe and then exposed to X-ray film (in the case of radioactive probes) or scanned (in the case of non-radioactive probes) to detect the location of the labeled probe on the membrane.

The position of the labeled probe on the membrane corresponds to the location of the specific DNA sequence within the original DNA sample. Southern blotting is a powerful tool for identifying and characterizing specific DNA sequences, such as those associated with genetic diseases or gene regulation.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Intracytoplasmic Sperm Injection (ICSI) is a specialized form of assisted reproductive technology (ART), specifically used in the context of in vitro fertilization (IVF). It involves the direct injection of a single sperm into the cytoplasm of a mature egg (oocyte) to facilitate fertilization. This technique is often used when there are issues with male infertility, such as low sperm count or poor sperm motility, to increase the chances of successful fertilization. The resulting embryos can then be transferred to the uterus in hopes of achieving a pregnancy.

Fertilization in vitro, also known as in-vitro fertilization (IVF), is a medical procedure where an egg (oocyte) and sperm are combined in a laboratory dish to facilitate fertilization. The fertilized egg (embryo) is then transferred to a uterus with the hope of establishing a successful pregnancy. This procedure is often used when other assisted reproductive technologies have been unsuccessful or are not applicable, such as in cases of blocked fallopian tubes, severe male factor infertility, and unexplained infertility. The process involves ovarian stimulation, egg retrieval, fertilization, embryo culture, and embryo transfer. In some cases, additional techniques such as intracytoplasmic sperm injection (ICSI) or preimplantation genetic testing (PGT) may be used to increase the chances of success.

Gene deletion is a type of mutation where a segment of DNA, containing one or more genes, is permanently lost or removed from a chromosome. This can occur due to various genetic mechanisms such as homologous recombination, non-homologous end joining, or other types of genomic rearrangements.

The deletion of a gene can have varying effects on the organism, depending on the function of the deleted gene and its importance for normal physiological processes. If the deleted gene is essential for survival, the deletion may result in embryonic lethality or developmental abnormalities. However, if the gene is non-essential or has redundant functions, the deletion may not have any noticeable effects on the organism's phenotype.

Gene deletions can also be used as a tool in genetic research to study the function of specific genes and their role in various biological processes. For example, researchers may use gene deletion techniques to create genetically modified animal models to investigate the impact of gene deletion on disease progression or development.

Chromosomal proteins, non-histone, are a diverse group of proteins that are associated with chromatin, the complex of DNA and histone proteins, but do not have the characteristic structure of histones. These proteins play important roles in various nuclear processes such as DNA replication, transcription, repair, recombination, and chromosome condensation and segregation during cell division. They can be broadly classified into several categories based on their functions, including architectural proteins, enzymes, transcription factors, and structural proteins. Examples of non-histone chromosomal proteins include high mobility group (HMG) proteins, poly(ADP-ribose) polymerases (PARPs), and condensins.

Chromosome walking is a historical term used in genetics to describe the process of mapping and sequencing DNA along a chromosome. It involves the identification and characterization of a specific starting point, or "landmark," on a chromosome, followed by the systematic analysis of adjacent DNA segments, one after another, in a step-by-step manner.

The technique typically employs the use of molecular biology tools such as restriction enzymes, cloning vectors, and genetic markers to physically isolate and characterize overlapping DNA fragments that cover the region of interest. By identifying shared sequences or markers between adjacent fragments, researchers can "walk" along the chromosome, gradually building up a more detailed map of the genetic sequence.

Chromosome walking was an important technique in the early days of genetics and genomics research, as it allowed scientists to systematically analyze large stretches of DNA before the advent of high-throughput sequencing technologies. Today, while whole-genome sequencing has largely replaced chromosome walking for many applications, the technique is still used in some specialized contexts where a targeted approach is required.

'Abnormalities, Multiple' is a broad term that refers to the presence of two or more structural or functional anomalies in an individual. These abnormalities can be present at birth (congenital) or can develop later in life (acquired). They can affect various organs and systems of the body and can vary greatly in severity and impact on a person's health and well-being.

Multiple abnormalities can occur due to genetic factors, environmental influences, or a combination of both. Chromosomal abnormalities, gene mutations, exposure to teratogens (substances that cause birth defects), and maternal infections during pregnancy are some of the common causes of multiple congenital abnormalities.

Examples of multiple congenital abnormalities include Down syndrome, Turner syndrome, and VATER/VACTERL association. Acquired multiple abnormalities can result from conditions such as trauma, infection, degenerative diseases, or cancer.

The medical evaluation and management of individuals with multiple abnormalities depend on the specific abnormalities present and their impact on the individual's health and functioning. A multidisciplinary team of healthcare professionals is often involved in the care of these individuals to address their complex needs.

Gene amplification is a process in molecular biology where a specific gene or set of genes are copied multiple times, leading to an increased number of copies of that gene within the genome. This can occur naturally in cells as a response to various stimuli, such as stress or exposure to certain chemicals, but it can also be induced artificially through laboratory techniques for research purposes.

In cancer biology, gene amplification is often associated with tumor development and progression, where the amplified genes can contribute to increased cell growth, survival, and drug resistance. For example, the overamplification of the HER2/neu gene in breast cancer has been linked to more aggressive tumors and poorer patient outcomes.

In diagnostic and research settings, gene amplification techniques like polymerase chain reaction (PCR) are commonly used to detect and analyze specific genes or genetic sequences of interest. These methods allow researchers to quickly and efficiently generate many copies of a particular DNA sequence, facilitating downstream analysis and detection of low-abundance targets.

An oocyte, also known as an egg cell or female gamete, is a large specialized cell found in the ovary of female organisms. It contains half the number of chromosomes as a normal diploid cell, as it is the product of meiotic division. Oocytes are surrounded by follicle cells and are responsible for the production of female offspring upon fertilization with sperm. The term "oocyte" specifically refers to the immature egg cell before it reaches full maturity and is ready for fertilization, at which point it is referred to as an ovum or egg.

Cell division is the process by which a single eukaryotic cell (a cell with a true nucleus) divides into two identical daughter cells. This complex process involves several stages, including replication of DNA, separation of chromosomes, and division of the cytoplasm. There are two main types of cell division: mitosis and meiosis.

Mitosis is the type of cell division that results in two genetically identical daughter cells. It is a fundamental process for growth, development, and tissue repair in multicellular organisms. The stages of mitosis include prophase, prometaphase, metaphase, anaphase, and telophase, followed by cytokinesis, which divides the cytoplasm.

Meiosis, on the other hand, is a type of cell division that occurs in the gonads (ovaries and testes) during the production of gametes (sex cells). Meiosis results in four genetically unique daughter cells, each with half the number of chromosomes as the parent cell. This process is essential for sexual reproduction and genetic diversity. The stages of meiosis include meiosis I and meiosis II, which are further divided into prophase, prometaphase, metaphase, anaphase, and telophase.

In summary, cell division is the process by which a single cell divides into two daughter cells, either through mitosis or meiosis. This process is critical for growth, development, tissue repair, and sexual reproduction in multicellular organisms.

Myopia, also known as nearsightedness, is a common refractive error of the eye. It occurs when the eye is either too long or the cornea (the clear front part of the eye) is too curved. As a result, light rays focus in front of the retina instead of directly on it, causing distant objects to appear blurry while close objects remain clear.

Myopia typically develops during childhood and can progress gradually or rapidly until early adulthood. It can be corrected with glasses, contact lenses, or refractive surgery such as LASIK. Regular eye examinations are essential for people with myopia to monitor any changes in their prescription and ensure proper correction.

While myopia is generally not a serious condition, high levels of nearsightedness can increase the risk of certain eye diseases, including cataracts, glaucoma, retinal detachment, and myopic degeneration. Therefore, it's crucial to manage myopia effectively and maintain regular follow-ups with an eye care professional.

Microinjection is a medical technique that involves the use of a fine, precise needle to inject small amounts of liquid or chemicals into microscopic structures, cells, or tissues. This procedure is often used in research settings to introduce specific substances into individual cells for study purposes, such as introducing DNA or RNA into cell nuclei to manipulate gene expression.

In clinical settings, microinjections may be used in various medical and cosmetic procedures, including:

1. Intracytoplasmic Sperm Injection (ICSI): A type of assisted reproductive technology where a single sperm is injected directly into an egg to increase the chances of fertilization during in vitro fertilization (IVF) treatments.
2. Botulinum Toxin Injections: Microinjections of botulinum toxin (Botox, Dysport, or Xeomin) are used for cosmetic purposes to reduce wrinkles and fine lines by temporarily paralyzing the muscles responsible for their formation. They can also be used medically to treat various neuromuscular disorders, such as migraines, muscle spasticity, and excessive sweating (hyperhidrosis).
3. Drug Delivery: Microinjections may be used to deliver drugs directly into specific tissues or organs, bypassing the systemic circulation and potentially reducing side effects. This technique can be particularly useful in treating localized pain, delivering growth factors for tissue regeneration, or administering chemotherapy agents directly into tumors.
4. Gene Therapy: Microinjections of genetic material (DNA or RNA) can be used to introduce therapeutic genes into cells to treat various genetic disorders or diseases, such as cystic fibrosis, hemophilia, or cancer.

Overall, microinjection is a highly specialized and precise technique that allows for the targeted delivery of substances into small structures, cells, or tissues, with potential applications in research, medical diagnostics, and therapeutic interventions.

A haplotype is a group of genes or DNA sequences that are inherited together from a single parent. It refers to a combination of alleles (variant forms of a gene) that are located on the same chromosome and are usually transmitted as a unit. Haplotypes can be useful in tracing genetic ancestry, understanding the genetic basis of diseases, and developing personalized medical treatments.

In population genetics, haplotypes are often used to study patterns of genetic variation within and between populations. By comparing haplotype frequencies across populations, researchers can infer historical events such as migrations, population expansions, and bottlenecks. Additionally, haplotypes can provide information about the evolutionary history of genes and genomic regions.

In clinical genetics, haplotypes can be used to identify genetic risk factors for diseases or to predict an individual's response to certain medications. For example, specific haplotypes in the HLA gene region have been associated with increased susceptibility to certain autoimmune diseases, while other haplotypes in the CYP450 gene family can affect how individuals metabolize drugs.

Overall, haplotypes provide a powerful tool for understanding the genetic basis of complex traits and diseases, as well as for developing personalized medical treatments based on an individual's genetic makeup.

Satellite DNA is a type of DNA sequence that is repeated in a tandem arrangement in the genome. These repeats are usually relatively short, ranging from 2 to 10 base pairs, and are often present in thousands to millions of copies arranged in head-to-tail fashion. Satellite DNA can be found in centromeric and pericentromeric regions of chromosomes, as well as at telomeres and other heterochromatic regions of the genome.

Due to their repetitive nature, satellite DNAs are often excluded from the main part of the genome during DNA sequencing projects, and therefore have been referred to as "satellite" DNA. However, recent studies suggest that satellite DNA may play important roles in chromosome structure, function, and evolution.

It's worth noting that not all repetitive DNA sequences are considered satellite DNA. For example, microsatellites and minisatellites are also repetitive DNA sequences, but they have different repeat lengths and arrangements than satellite DNA.

DNA Copy Number Variations (CNVs) refer to deletions or duplications of sections of the DNA molecule that are larger than 1 kilobase (kb). These variations result in gains or losses of genetic material, leading to changes in the number of copies of a particular gene or genes. CNVs can affect the expression level of genes and have been associated with various genetic disorders, complex diseases, and phenotypic differences among individuals. They are typically detected through techniques such as array comparative genomic hybridization (aCGH), single nucleotide polymorphism (SNP) arrays, or next-generation sequencing (NGS).

Lymphoma is a type of cancer that originates from the white blood cells called lymphocytes, which are part of the immune system. These cells are found in various parts of the body such as the lymph nodes, spleen, bone marrow, and other organs. Lymphoma can be classified into two main types: Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL).

HL is characterized by the presence of a specific type of abnormal lymphocyte called Reed-Sternberg cells, while NHL includes a diverse group of lymphomas that lack these cells. The symptoms of lymphoma may include swollen lymph nodes, fever, night sweats, weight loss, and fatigue.

The exact cause of lymphoma is not known, but it is believed to result from genetic mutations in the lymphocytes that lead to uncontrolled cell growth and division. Exposure to certain viruses, chemicals, and radiation may increase the risk of developing lymphoma. Treatment options for lymphoma depend on various factors such as the type and stage of the disease, age, and overall health of the patient. Common treatments include chemotherapy, radiation therapy, immunotherapy, and stem cell transplantation.

Quantitative Trait Loci (QTL) are regions of the genome that are associated with variation in quantitative traits, which are traits that vary continuously in a population and are influenced by multiple genes and environmental factors. QTLs can help to explain how genetic variations contribute to differences in complex traits such as height, blood pressure, or disease susceptibility.

Quantitative trait loci are identified through statistical analysis of genetic markers and trait values in experimental crosses between genetically distinct individuals, such as strains of mice or plants. The location of a QTL is inferred based on the pattern of linkage disequilibrium between genetic markers and the trait of interest. Once a QTL has been identified, further analysis can be conducted to identify the specific gene or genes responsible for the variation in the trait.

It's important to note that QTLs are not themselves genes, but rather genomic regions that contain one or more genes that contribute to the variation in a quantitative trait. Additionally, because QTLs are identified through statistical analysis, they represent probabilistic estimates of the location of genetic factors influencing a trait and may encompass large genomic regions containing multiple genes. Therefore, additional research is often required to fine-map and identify the specific genes responsible for the variation in the trait.

I'm sorry for any confusion, but "Japan" is not a medical term. Japan is the name of a country, officially known as Nippon-koku or Nihon-koku in Japanese, and is located in East Asia. It is an island nation in the Pacific Ocean with a population of about 126 million people.

If you have any medical questions or terms that you would like me to define, please let me know!

A heterozygote is an individual who has inherited two different alleles (versions) of a particular gene, one from each parent. This means that the individual's genotype for that gene contains both a dominant and a recessive allele. The dominant allele will be expressed phenotypically (outwardly visible), while the recessive allele may or may not have any effect on the individual's observable traits, depending on the specific gene and its function. Heterozygotes are often represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.

The G2 phase, also known as the "gap 2 phase," is a stage in the cell cycle that occurs after DNA replication (S phase) and before cell division (mitosis). During this phase, the cell prepares for mitosis by completing the synthesis of proteins and organelles needed for chromosome separation. The cell also checks for any errors or damage to the DNA before entering mitosis. This phase is a critical point in the cell cycle where proper regulation ensures the faithful transmission of genetic information from one generation of cells to the next. If significant DNA damage is detected during G2, the cell may undergo programmed cell death (apoptosis) instead of dividing.

A chromosome breakpoint is a specific location on a chromosome where a chromosomal rearrangement, such as a translocation or inversion, has occurred. A breakpoint is the point at which the chromosome has broken and then rejoined, often with another chromosome, resulting in a changed genetic sequence. These changes can have various consequences, including altered gene expression, loss of genetic material, or gain of new genetic material, which can lead to genetic disorders or predisposition to certain diseases. The identification and characterization of breakpoints are important for understanding the molecular basis of genomic rearrangements and their associated phenotypes.

Bleomycin is a type of chemotherapeutic agent used to treat various types of cancer, including squamous cell carcinoma, testicular cancer, and lymphomas. It works by causing DNA damage in rapidly dividing cells, which can inhibit the growth and proliferation of cancer cells.

Bleomycin is an antibiotic derived from Streptomyces verticillus and is often administered intravenously or intramuscularly. While it can be effective in treating certain types of cancer, it can also have serious side effects, including lung toxicity, which can lead to pulmonary fibrosis and respiratory failure. Therefore, bleomycin should only be used under the close supervision of a healthcare professional who is experienced in administering chemotherapy drugs.

A gene is a specific sequence of nucleotides in DNA that carries genetic information. Genes are the fundamental units of heredity and are responsible for the development and function of all living organisms. They code for proteins or RNA molecules, which carry out various functions within cells and are essential for the structure, function, and regulation of the body's tissues and organs.

Each gene has a specific location on a chromosome, and each person inherits two copies of every gene, one from each parent. Variations in the sequence of nucleotides in a gene can lead to differences in traits between individuals, including physical characteristics, susceptibility to disease, and responses to environmental factors.

Medical genetics is the study of genes and their role in health and disease. It involves understanding how genes contribute to the development and progression of various medical conditions, as well as identifying genetic risk factors and developing strategies for prevention, diagnosis, and treatment.

Repetitive sequences in nucleic acid refer to repeated stretches of DNA or RNA nucleotide bases that are present in a genome. These sequences can vary in length and can be arranged in different patterns such as direct repeats, inverted repeats, or tandem repeats. In some cases, these repetitive sequences do not code for proteins and are often found in non-coding regions of the genome. They can play a role in genetic instability, regulation of gene expression, and evolutionary processes. However, certain types of repeat expansions have been associated with various neurodegenerative disorders and other human diseases.

"Mesocricetus" is a genus of rodents, more commonly known as hamsters. It includes several species of hamsters that are native to various parts of Europe and Asia. The best-known member of this genus is the Syrian hamster, also known as the golden hamster or Mesocricetus auratus, which is a popular pet due to its small size and relatively easy care. These hamsters are burrowing animals and are typically solitary in the wild.

Nuclear proteins are a category of proteins that are primarily found in the nucleus of a eukaryotic cell. They play crucial roles in various nuclear functions, such as DNA replication, transcription, repair, and RNA processing. This group includes structural proteins like lamins, which form the nuclear lamina, and regulatory proteins, such as histones and transcription factors, that are involved in gene expression. Nuclear localization signals (NLS) often help target these proteins to the nucleus by interacting with importin proteins during active transport across the nuclear membrane.

I'm sorry for any confusion, but "Optics and Photonics" is a broad field that encompasses various scientific and engineering disciplines. It doesn't have a specific medical definition, as it's not a term typically used in a medical context.

However, I can provide a general definition:

Optics is the study of light and its interactions with matter. This includes how light is produced, controlled, transmitted, and detected. It involves phenomena such as reflection, refraction, diffraction, and interference.

Photonics, on the other hand, is a branch of optics that deals with the generation, detection, and manipulation of individual photons, the basic units of light. Photonics is often applied to technologies such as lasers, fiber optics, and optical communications.

In a medical context, these fields might be used in various diagnostic and therapeutic applications, such as endoscopes, ophthalmic devices, laser surgery, and imaging technologies like MRI and CT scans. But the terms "Optics" and "Photonics" themselves are not medical conditions or treatments.

Protein-Serine-Threonine Kinases (PSTKs) are a type of protein kinase that catalyzes the transfer of a phosphate group from ATP to the hydroxyl side chains of serine or threonine residues on target proteins. This phosphorylation process plays a crucial role in various cellular signaling pathways, including regulation of metabolism, gene expression, cell cycle progression, and apoptosis. PSTKs are involved in many physiological and pathological processes, and their dysregulation has been implicated in several diseases, such as cancer, diabetes, and neurodegenerative disorders.

Chromosome fragile sites are specific locations along the length of a chromosome that are prone to breakage or rearrangement when exposed to certain chemicals or conditions, such as replication stress during cell division. These sites are often characterized by the presence of repetitive DNA sequences and proteins that help maintain the stability of the chromosome.

Fragile sites can be classified into two categories: common and rare. Common fragile sites are present in most individuals and are typically not associated with genetic disorders, while rare fragile sites are less common and may be linked to specific genetic conditions or increased risk for cancer.

When a chromosome breaks at a fragile site, it can lead to various genetic abnormalities such as deletions, duplications, inversions, or translocations of genetic material. These changes can have significant consequences on gene expression and function, potentially leading to developmental disorders, intellectual disability, cancer, or other health issues.

It is important to note that not all fragile sites will result in genetic abnormalities, as some may remain stable under normal conditions. However, certain factors such as environmental exposures, aging, or inherited genetic predispositions can increase the likelihood of chromosomal instability at fragile sites.

Molecular evolution is the process of change in the DNA sequence or protein structure over time, driven by mechanisms such as mutation, genetic drift, gene flow, and natural selection. It refers to the evolutionary study of changes in DNA, RNA, and proteins, and how these changes accumulate and lead to new species and diversity of life. Molecular evolution can be used to understand the history and relationships among different organisms, as well as the functional consequences of genetic changes.

Leukocytes, also known as white blood cells (WBCs), are a crucial component of the human immune system. They are responsible for protecting the body against infections and foreign substances. Leukocytes are produced in the bone marrow and circulate throughout the body in the bloodstream and lymphatic system.

There are several types of leukocytes, including:

1. Neutrophils - These are the most abundant type of leukocyte and are primarily responsible for fighting bacterial infections. They contain enzymes that can destroy bacteria.
2. Lymphocytes - These are responsible for producing antibodies and destroying virus-infected cells, as well as cancer cells. There are two main types of lymphocytes: B-lymphocytes and T-lymphocytes.
3. Monocytes - These are the largest type of leukocyte and help to break down and remove dead or damaged tissues, as well as microorganisms.
4. Eosinophils - These play a role in fighting parasitic infections and are also involved in allergic reactions and inflammation.
5. Basophils - These release histamine and other chemicals that cause inflammation in response to allergens or irritants.

An abnormal increase or decrease in the number of leukocytes can indicate an underlying medical condition, such as an infection, inflammation, or a blood disorder.

Single Nucleotide Polymorphism (SNP) is a type of genetic variation that occurs when a single nucleotide (A, T, C, or G) in the DNA sequence is altered. This alteration must occur in at least 1% of the population to be considered a SNP. These variations can help explain why some people are more susceptible to certain diseases than others and can also influence how an individual responds to certain medications. SNPs can serve as biological markers, helping scientists locate genes that are associated with disease. They can also provide information about an individual's ancestry and ethnic background.

Spectral karyotyping (SKY) is a molecular cytogenetic technique used to analyze the chromosomal composition and structure of cells. It involves the use of fluorescent probes that bind specifically to each chromosome pair, with each probe labeled with a different color. This allows for the visualization of individual chromosomes in multiple colors throughout the genome, creating a "spectrum" of colors for each chromosome pair.

The technique is particularly useful in identifying complex chromosomal rearrangements, such as translocations, deletions, and duplications, that may be associated with various genetic disorders or cancer. By comparing the spectral karyotype of a patient's cells to a normal reference karyotype, researchers and clinicians can identify abnormalities and gain insights into the underlying genetic causes of diseases.

Overall, spectral karyotyping is an important tool in the field of genetics and genomics, providing a powerful means of visualizing and analyzing chromosomal structure and composition at the molecular level.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

Ataxia telangiectasia mutated (ATM) proteins are a type of protein that play a crucial role in the maintenance and repair of DNA in cells. The ATM gene produces these proteins, which are involved in several important cellular processes such as:

1. DNA damage response: When DNA is damaged, ATM proteins help to detect and respond to the damage by activating various signaling pathways that lead to DNA repair or apoptosis (programmed cell death) if the damage is too severe.
2. Cell cycle regulation: ATM proteins regulate the cell cycle by controlling checkpoints that ensure proper DNA replication and division. This helps prevent the propagation of cells with damaged DNA.
3. Telomere maintenance: ATM proteins help maintain telomeres, which are the protective caps at the ends of chromosomes. Telomeres shorten as cells divide, and when they become too short, cells can no longer divide and enter a state of senescence or die.

Mutations in the ATM gene can lead to Ataxia-telangiectasia (A-T), a rare inherited disorder characterized by neurological problems, immune system dysfunction, increased risk of cancer, and sensitivity to ionizing radiation. People with A-T have defective ATM proteins that cannot properly respond to DNA damage, leading to genomic instability and increased susceptibility to disease.

A cell line that is derived from tumor cells and has been adapted to grow in culture. These cell lines are often used in research to study the characteristics of cancer cells, including their growth patterns, genetic changes, and responses to various treatments. They can be established from many different types of tumors, such as carcinomas, sarcomas, and leukemias. Once established, these cell lines can be grown and maintained indefinitely in the laboratory, allowing researchers to conduct experiments and studies that would not be feasible using primary tumor cells. It is important to note that tumor cell lines may not always accurately represent the behavior of the original tumor, as they can undergo genetic changes during their time in culture.

Occupational air pollutants refer to harmful substances present in the air in workplaces or occupational settings. These pollutants can include dusts, gases, fumes, vapors, or mists that are produced by industrial processes, chemical reactions, or other sources. Examples of occupational air pollutants include:

1. Respirable crystalline silica: A common mineral found in sand, stone, and concrete that can cause lung disease and cancer when inhaled in high concentrations.
2. Asbestos: A naturally occurring mineral fiber that was widely used in construction materials and industrial applications until the 1970s. Exposure to asbestos fibers can cause lung diseases such as asbestosis, lung cancer, and mesothelioma.
3. Welding fumes: Fumes generated during welding processes can contain harmful metals such as manganese, chromium, and nickel that can cause neurological damage and respiratory problems.
4. Isocyanates: Chemicals used in the production of foam insulation, spray-on coatings, and other industrial applications that can cause asthma and other respiratory symptoms.
5. Coal dust: Fine particles generated during coal mining, transportation, and handling that can cause lung disease and other health problems.
6. Diesel exhaust: Emissions from diesel engines that contain harmful particulates and gases that can cause respiratory and cardiovascular problems.

Occupational air pollutants are regulated by various government agencies, including the Occupational Safety and Health Administration (OSHA) in the United States, to protect workers from exposure and minimize health risks.

A multigene family is a group of genetically related genes that share a common ancestry and have similar sequences or structures. These genes are arranged in clusters on a chromosome and often encode proteins with similar functions. They can arise through various mechanisms, including gene duplication, recombination, and transposition. Multigene families play crucial roles in many biological processes, such as development, immunity, and metabolism. Examples of multigene families include the globin genes involved in oxygen transport, the immune system's major histocompatibility complex (MHC) genes, and the cytochrome P450 genes associated with drug metabolism.

Genetic predisposition to disease refers to an increased susceptibility or vulnerability to develop a particular illness or condition due to inheriting specific genetic variations or mutations from one's parents. These genetic factors can make it more likely for an individual to develop a certain disease, but it does not guarantee that the person will definitely get the disease. Environmental factors, lifestyle choices, and interactions between genes also play crucial roles in determining if a genetically predisposed person will actually develop the disease. It is essential to understand that having a genetic predisposition only implies a higher risk, not an inevitable outcome.

Genetic variation refers to the differences in DNA sequences among individuals and populations. These variations can result from mutations, genetic recombination, or gene flow between populations. Genetic variation is essential for evolution by providing the raw material upon which natural selection acts. It can occur within a single gene, between different genes, or at larger scales, such as differences in the number of chromosomes or entire sets of chromosomes. The study of genetic variation is crucial in understanding the genetic basis of diseases and traits, as well as the evolutionary history and relationships among species.

Genetic polymorphism refers to the occurrence of multiple forms (called alleles) of a particular gene within a population. These variations in the DNA sequence do not generally affect the function or survival of the organism, but they can contribute to differences in traits among individuals. Genetic polymorphisms can be caused by single nucleotide changes (SNPs), insertions or deletions of DNA segments, or other types of genetic rearrangements. They are important for understanding genetic diversity and evolution, as well as for identifying genetic factors that may contribute to disease susceptibility in humans.

Bone marrow cells are the types of cells found within the bone marrow, which is the spongy tissue inside certain bones in the body. The main function of bone marrow is to produce blood cells. There are two types of bone marrow: red and yellow. Red bone marrow is where most blood cell production takes place, while yellow bone marrow serves as a fat storage site.

The three main types of bone marrow cells are:

1. Hematopoietic stem cells (HSCs): These are immature cells that can differentiate into any type of blood cell, including red blood cells, white blood cells, and platelets. They have the ability to self-renew, meaning they can divide and create more hematopoietic stem cells.
2. Red blood cell progenitors: These are immature cells that will develop into mature red blood cells, also known as erythrocytes. Red blood cells carry oxygen from the lungs to the body's tissues and carbon dioxide back to the lungs.
3. Myeloid and lymphoid white blood cell progenitors: These are immature cells that will develop into various types of white blood cells, which play a crucial role in the body's immune system by fighting infections and diseases. Myeloid progenitors give rise to granulocytes (neutrophils, eosinophils, and basophils), monocytes, and megakaryocytes (which eventually become platelets). Lymphoid progenitors differentiate into B cells, T cells, and natural killer (NK) cells.

Bone marrow cells are essential for maintaining a healthy blood cell count and immune system function. Abnormalities in bone marrow cells can lead to various medical conditions, such as anemia, leukopenia, leukocytosis, thrombocytopenia, or thrombocytosis, depending on the specific type of blood cell affected. Additionally, bone marrow cells are often used in transplantation procedures to treat patients with certain types of cancer, such as leukemia and lymphoma, or other hematologic disorders.

Spermatocytes are a type of cell that is involved in the process of spermatogenesis, which is the formation of sperm in the testes. Specifically, spermatocytes are the cells that undergo meiosis, a special type of cell division that results in the production of four haploid daughter cells, each containing half the number of chromosomes as the parent cell.

There are two types of spermatocytes: primary and secondary. Primary spermatocytes are diploid cells that contain 46 chromosomes (23 pairs). During meiosis I, these cells undergo a process called crossing over, in which genetic material is exchanged between homologous chromosomes. After crossing over, the primary spermatocytes divide into two secondary spermatocytes, each containing 23 chromosomes (but still with 23 pairs).

Secondary spermatocytes then undergo meiosis II, which results in the formation of four haploid spermatids. Each spermatid contains 23 single chromosomes and will eventually develop into a mature sperm cell through a process called spermiogenesis.

It's worth noting that spermatocytes are only found in males, as they are specific to the male reproductive system.

Laser In Situ Keratomileusis (LASIK) is a type of refractive surgery used to correct vision issues such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The procedure involves reshaping the cornea, which is the clear, dome-shaped surface at the front of the eye, using an excimer laser.

In LASIK, a thin flap is created on the surface of the cornea using a femtosecond or microkeratome laser. The flap is then lifted, and the excimer laser is used to reshape the underlying tissue. After the reshaping is complete, the flap is replaced, allowing for quicker healing and visual recovery compared to other refractive surgery procedures.

LASIK is an outpatient procedure that typically takes about 30 minutes or less per eye. Most people can expect to see improved vision within a few days of the procedure, although it may take several weeks for vision to fully stabilize. LASIK has a high success rate and is generally considered safe when performed by a qualified surgeon. However, as with any surgical procedure, there are risks involved, including dry eye, infection, and visual complications such as glare or halos around lights.

CHO cells, or Chinese Hamster Ovary cells, are a type of immortalized cell line that are commonly used in scientific research and biotechnology. They were originally derived from the ovaries of a female Chinese hamster (Cricetulus griseus) in the 1950s.

CHO cells have several characteristics that make them useful for laboratory experiments. They can grow and divide indefinitely under appropriate conditions, which allows researchers to culture large quantities of them for study. Additionally, CHO cells are capable of expressing high levels of recombinant proteins, making them a popular choice for the production of therapeutic drugs, vaccines, and other biologics.

In particular, CHO cells have become a workhorse in the field of biotherapeutics, with many approved monoclonal antibody-based therapies being produced using these cells. The ability to genetically modify CHO cells through various methods has further expanded their utility in research and industrial applications.

It is important to note that while CHO cells are widely used in scientific research, they may not always accurately represent human cell behavior or respond to drugs and other compounds in the same way as human cells do. Therefore, results obtained using CHO cells should be validated in more relevant systems when possible.

Oligonucleotide Array Sequence Analysis is a type of microarray analysis that allows for the simultaneous measurement of the expression levels of thousands of genes in a single sample. In this technique, oligonucleotides (short DNA sequences) are attached to a solid support, such as a glass slide, in a specific pattern. These oligonucleotides are designed to be complementary to specific target mRNA sequences from the sample being analyzed.

During the analysis, labeled RNA or cDNA from the sample is hybridized to the oligonucleotide array. The level of hybridization is then measured and used to determine the relative abundance of each target sequence in the sample. This information can be used to identify differences in gene expression between samples, which can help researchers understand the underlying biological processes involved in various diseases or developmental stages.

It's important to note that this technique requires specialized equipment and bioinformatics tools for data analysis, as well as careful experimental design and validation to ensure accurate and reproducible results.

Polytene chromosomes are highly specialized and significantly enlarged chromosomes that are formed by the endoreduplication process, where multiple rounds of DNA replication occur without cell division. This results in the formation of several identical sister chromatids that remain tightly associated with each other, forming a single, visually thick and banded structure. These chromosomes are typically found in the cells of certain insects, such as dipteran flies, and are particularly prominent during the larval stages of development. Polytene chromosomes play crucial roles in various biological processes, including growth, development, and gene regulation. The distinctive banding pattern observed in polytene chromosomes is often used in genetic studies to map the locations of specific genes within the genome.

A genome is the complete set of genetic material (DNA, or in some viruses, RNA) present in a single cell of an organism. It includes all of the genes, both coding and noncoding, as well as other regulatory elements that together determine the unique characteristics of that organism. The human genome, for example, contains approximately 3 billion base pairs and about 20,000-25,000 protein-coding genes.

The term "genome" was first coined by Hans Winkler in 1920, derived from the word "gene" and the suffix "-ome," which refers to a complete set of something. The study of genomes is known as genomics.

Understanding the genome can provide valuable insights into the genetic basis of diseases, evolution, and other biological processes. With advancements in sequencing technologies, it has become possible to determine the entire genomic sequence of many organisms, including humans, and use this information for various applications such as personalized medicine, gene therapy, and biotechnology.

Chromatin is the complex of DNA, RNA, and proteins that make up the chromosomes in the nucleus of a cell. It is responsible for packaging the long DNA molecules into a more compact form that fits within the nucleus. Chromatin is made up of repeating units called nucleosomes, which consist of a histone protein octamer wrapped tightly by DNA. The structure of chromatin can be altered through chemical modifications to the histone proteins and DNA, which can influence gene expression and other cellular processes.

Environmental monitoring is the systematic and ongoing surveillance, measurement, and assessment of environmental parameters, pollutants, or other stressors in order to evaluate potential impacts on human health, ecological systems, or compliance with regulatory standards. This process typically involves collecting and analyzing data from various sources, such as air, water, soil, and biota, and using this information to inform decisions related to public health, environmental protection, and resource management.

In medical terms, environmental monitoring may refer specifically to the assessment of environmental factors that can impact human health, such as air quality, water contamination, or exposure to hazardous substances. This type of monitoring is often conducted in occupational settings, where workers may be exposed to potential health hazards, as well as in community-based settings, where environmental factors may contribute to public health issues. The goal of environmental monitoring in a medical context is to identify and mitigate potential health risks associated with environmental exposures, and to promote healthy and safe environments for individuals and communities.

A plant extract is a preparation containing chemical constituents that have been extracted from a plant using a solvent. The resulting extract may contain a single compound or a mixture of several compounds, depending on the extraction process and the specific plant material used. These extracts are often used in various industries including pharmaceuticals, nutraceuticals, cosmetics, and food and beverage, due to their potential therapeutic or beneficial properties. The composition of plant extracts can vary widely, and it is important to ensure their quality, safety, and efficacy before use in any application.

Prophase is the first phase of mitosis, the process by which eukaryotic cells divide and reproduce. During prophase, the chromosomes condense and become visible. The nuclear envelope breaks down, allowing the spindle fibers to attach to the centromeres of each chromatid in the chromosome. This is a critical step in preparing for the separation of genetic material during cell division. Prophase is also marked by the movement of the centrosomes to opposite poles of the cell, forming the mitotic spindle.

The Philadelphia chromosome is a specific genetic alteration in certain types of leukemia and lymphoma, including chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL). It is the result of a translocation between chromosomes 9 and 22, which forms an abnormal fusion gene called BCR-ABL. This gene produces an abnormal protein that leads to unregulated cell growth and division, causing cancer. The Philadelphia chromosome was first discovered in Philadelphia, USA, hence the name.

Intellectual disability (ID) is a term used when there are significant limitations in both intellectual functioning and adaptive behavior, which covers many everyday social and practical skills. This disability originates before the age of 18.

Intellectual functioning, also known as intelligence, refers to general mental capacity, such as learning, reasoning, problem-solving, and other cognitive skills. Adaptive behavior includes skills needed for day-to-day life, such as communication, self-care, social skills, safety judgement, and basic academic skills.

Intellectual disability is characterized by below-average intelligence or mental ability and a lack of skills necessary for day-to-day living. It can be mild, moderate, severe, or profound, depending on the degree of limitation in intellectual functioning and adaptive behavior.

It's important to note that people with intellectual disabilities have unique strengths and limitations, just like everyone else. With appropriate support and education, they can lead fulfilling lives and contribute to their communities in many ways.

The cell nucleus is a membrane-bound organelle found in the eukaryotic cells (cells with a true nucleus). It contains most of the cell's genetic material, organized as DNA molecules in complex with proteins, RNA molecules, and histones to form chromosomes.

The primary function of the cell nucleus is to regulate and control the activities of the cell, including growth, metabolism, protein synthesis, and reproduction. It also plays a crucial role in the process of mitosis (cell division) by separating and protecting the genetic material during this process. The nuclear membrane, or nuclear envelope, surrounding the nucleus is composed of two lipid bilayers with numerous pores that allow for the selective transport of molecules between the nucleoplasm (nucleus interior) and the cytoplasm (cell exterior).

The cell nucleus is a vital structure in eukaryotic cells, and its dysfunction can lead to various diseases, including cancer and genetic disorders.

A homozygote is an individual who has inherited the same allele (version of a gene) from both parents and therefore possesses two identical copies of that allele at a specific genetic locus. This can result in either having two dominant alleles (homozygous dominant) or two recessive alleles (homozygous recessive). In contrast, a heterozygote has inherited different alleles from each parent for a particular gene.

The term "homozygote" is used in genetics to describe the genetic makeup of an individual at a specific locus on their chromosomes. Homozygosity can play a significant role in determining an individual's phenotype (observable traits), as having two identical alleles can strengthen the expression of certain characteristics compared to having just one dominant and one recessive allele.

Refractive surgical procedures are a type of ophthalmic surgery aimed at improving the refractive state of the eye and reducing or eliminating the need for corrective eyewear. These procedures reshape the cornea or alter the lens of the eye to correct nearsightedness (myopia), farsightedness (hyperopia), presbyopia, or astigmatism.

Examples of refractive surgical procedures include:

1. Laser-assisted in situ keratomileusis (LASIK): A laser is used to create a thin flap in the cornea, which is then lifted to allow reshaping of the underlying tissue with another laser. The flap is replaced, and the procedure is completed.
2. Photorefractive keratectomy (PRK): This procedure involves removing the outer layer of the cornea (epithelium) and using a laser to reshape the underlying tissue. A bandage contact lens is placed over the eye to protect it during healing.
3. LASEK (laser-assisted subepithelial keratomileusis): Similar to LASIK, but instead of creating a flap, the epithelium is loosened with an alcohol solution and moved aside. The laser treatment is applied, and the epithelium is replaced.
4. Small Incision Lenticule Extraction (SMILE): A femtosecond laser creates a small lenticule within the cornea, which is then removed through a tiny incision. This procedure reshapes the cornea to correct refractive errors.
5. Refractive lens exchange (RLE): The eye's natural lens is removed and replaced with an artificial intraocular lens (IOL) to correct refractive errors, similar to cataract surgery.
6. Implantable contact lenses: A thin, foldable lens is placed between the iris and the natural lens or behind the iris to improve the eye's focusing power.

These procedures are typically performed on an outpatient basis and may require topical anesthesia (eye drops) or local anesthesia. Potential risks and complications include infection, dry eye, visual disturbances, and changes in night vision. It is essential to discuss these potential risks with your ophthalmologist before deciding on a refractive surgery procedure.

Restriction Fragment Length Polymorphism (RFLP) is a term used in molecular biology and genetics. It refers to the presence of variations in DNA sequences among individuals, which can be detected by restriction enzymes. These enzymes cut DNA at specific sites, creating fragments of different lengths.

In RFLP analysis, DNA is isolated from an individual and treated with a specific restriction enzyme that cuts the DNA at particular recognition sites. The resulting fragments are then separated by size using gel electrophoresis, creating a pattern unique to that individual's DNA. If there are variations in the DNA sequence between individuals, the restriction enzyme may cut the DNA at different sites, leading to differences in the length of the fragments and thus, a different pattern on the gel.

These variations can be used for various purposes, such as identifying individuals, diagnosing genetic diseases, or studying evolutionary relationships between species. However, RFLP analysis has largely been replaced by more modern techniques like polymerase chain reaction (PCR)-based methods and DNA sequencing, which offer higher resolution and throughput.

Haploidy is a term used in genetics to describe the condition of having half the normal number of chromosomes in a cell or an organism. In humans, for example, a haploid cell contains 23 chromosomes, whereas a diploid cell has 46 chromosomes.

Haploid cells are typically produced through a process called meiosis, which is a type of cell division that occurs in the reproductive organs of sexually reproducing organisms. During meiosis, a diploid cell undergoes two rounds of division to produce four haploid cells, each containing only one set of chromosomes.

In humans, haploid cells are found in the sperm and egg cells, which fuse together during fertilization to create a diploid zygote with 46 chromosomes. Haploidy is important for maintaining the correct number of chromosomes in future generations and preventing genetic abnormalities that can result from having too many or too few chromosomes.

Species specificity is a term used in the field of biology, including medicine, to refer to the characteristic of a biological entity (such as a virus, bacterium, or other microorganism) that allows it to interact exclusively or preferentially with a particular species. This means that the biological entity has a strong affinity for, or is only able to infect, a specific host species.

For example, HIV is specifically adapted to infect human cells and does not typically infect other animal species. Similarly, some bacterial toxins are species-specific and can only affect certain types of animals or humans. This concept is important in understanding the transmission dynamics and host range of various pathogens, as well as in developing targeted therapies and vaccines.

Cosmids are a type of cloning vector, which are self-replicating DNA molecules that can be used to introduce foreign DNA fragments into a host organism. Cosmids are plasmids that contain the cos site from bacteriophage λ, allowing them to be packaged into bacteriophage heads during an in vitro packaging reaction. This enables the transfer of large DNA fragments (up to 45 kb) into a host cell through transduction. Cosmids are widely used in molecular biology for the construction and analysis of genomic libraries, physical mapping, and DNA sequencing.

A plasmid is a small, circular, double-stranded DNA molecule that is separate from the chromosomal DNA of a bacterium or other organism. Plasmids are typically not essential for the survival of the organism, but they can confer beneficial traits such as antibiotic resistance or the ability to degrade certain types of pollutants.

Plasmids are capable of replicating independently of the chromosomal DNA and can be transferred between bacteria through a process called conjugation. They often contain genes that provide resistance to antibiotics, heavy metals, and other environmental stressors. Plasmids have also been engineered for use in molecular biology as cloning vectors, allowing scientists to replicate and manipulate specific DNA sequences.

Plasmids are important tools in genetic engineering and biotechnology because they can be easily manipulated and transferred between organisms. They have been used to produce vaccines, diagnostic tests, and genetically modified organisms (GMOs) for various applications, including agriculture, medicine, and industry.

Flow cytometry is a medical and research technique used to measure physical and chemical characteristics of cells or particles, one cell at a time, as they flow in a fluid stream through a beam of light. The properties measured include:

* Cell size (light scatter)
* Cell internal complexity (granularity, also light scatter)
* Presence or absence of specific proteins or other molecules on the cell surface or inside the cell (using fluorescent antibodies or other fluorescent probes)

The technique is widely used in cell counting, cell sorting, protein engineering, biomarker discovery and monitoring disease progression, particularly in hematology, immunology, and cancer research.

"Saccharomyces cerevisiae" is not typically considered a medical term, but it is a scientific name used in the field of microbiology. It refers to a species of yeast that is commonly used in various industrial processes, such as baking and brewing. It's also widely used in scientific research due to its genetic tractability and eukaryotic cellular organization.

However, it does have some relevance to medical fields like medicine and nutrition. For example, certain strains of S. cerevisiae are used as probiotics, which can provide health benefits when consumed. They may help support gut health, enhance the immune system, and even assist in the digestion of certain nutrients.

In summary, "Saccharomyces cerevisiae" is a species of yeast with various industrial and potential medical applications.

Dominant genes refer to the alleles (versions of a gene) that are fully expressed in an individual's phenotype, even if only one copy of the gene is present. In dominant inheritance patterns, an individual needs only to receive one dominant allele from either parent to express the associated trait. This is in contrast to recessive genes, where both copies of the gene must be the recessive allele for the trait to be expressed. Dominant genes are represented by uppercase letters (e.g., 'A') and recessive genes by lowercase letters (e.g., 'a'). If an individual inherits one dominant allele (A) from either parent, they will express the dominant trait (A).

A case-control study is an observational research design used to identify risk factors or causes of a disease or health outcome. In this type of study, individuals with the disease or condition (cases) are compared with similar individuals who do not have the disease or condition (controls). The exposure history or other characteristics of interest are then compared between the two groups to determine if there is an association between the exposure and the disease.

Case-control studies are often used when it is not feasible or ethical to conduct a randomized controlled trial, as they can provide valuable insights into potential causes of diseases or health outcomes in a relatively short period of time and at a lower cost than other study designs. However, because case-control studies rely on retrospective data collection, they are subject to biases such as recall bias and selection bias, which can affect the validity of the results. Therefore, it is important to carefully design and conduct case-control studies to minimize these potential sources of bias.

Sex chromosome disorders are genetic conditions that occur due to an atypical number or structure of the sex chromosomes, which are X and Y. Normally, females have two X chromosomes (XX), and males have one X and one Y chromosome (XY). However, in sex chromosome disorders, there is a variation in the number or composition of these chromosomes.

The most common sex chromosome disorders include:

1. Turner syndrome (Monosomy X): Occurs when a female has only one X chromosome (45,X). This condition affects about 1 in every 2,500 female births and can lead to short stature, infertility, heart defects, and learning disabilities.
2. Klinefelter syndrome (XXY): Occurs when a male has an extra X chromosome (47,XXY). This condition affects about 1 in every 500-1,000 male births and can lead to tall stature, infertility, breast development, and learning disabilities.
3. Jacobs syndrome (XYY): Occurs when a male has an extra Y chromosome (47,XYY). This condition affects about 1 in every 1,000 male births and can lead to tall stature, learning disabilities, and behavioral issues.
4. Triple X syndrome (XXX): Occurs when a female has an extra X chromosome (47,XXX). This condition affects about 1 in every 1,000 female births and can lead to mild developmental delays and learning disabilities.
5. Other rare sex chromosome disorders: These include conditions like 48,XXXX, 49,XXXXY, and mosaicism (a mixture of cells with different chromosome compositions).

Sex chromosome disorders can have varying degrees of impact on an individual's physical and cognitive development. While some individuals may experience significant challenges, others may have only mild or no symptoms at all. Early diagnosis and appropriate interventions can help improve outcomes for those affected by sex chromosome disorders.

DNA primers are short single-stranded DNA molecules that serve as a starting point for DNA synthesis. They are typically used in laboratory techniques such as the polymerase chain reaction (PCR) and DNA sequencing. The primer binds to a complementary sequence on the DNA template through base pairing, providing a free 3'-hydroxyl group for the DNA polymerase enzyme to add nucleotides and synthesize a new strand of DNA. This allows for specific and targeted amplification or analysis of a particular region of interest within a larger DNA molecule.

A newborn infant is a baby who is within the first 28 days of life. This period is also referred to as the neonatal period. Newborns require specialized care and attention due to their immature bodily systems and increased vulnerability to various health issues. They are closely monitored for signs of well-being, growth, and development during this critical time.

X-linked genes are those genes that are located on the X chromosome. In humans, females have two copies of the X chromosome (XX), while males have one X and one Y chromosome (XY). This means that males have only one copy of each X-linked gene, whereas females have two copies.

X-linked genes are important in medical genetics because they can cause different patterns of inheritance and disease expression between males and females. For example, if a mutation occurs in an X-linked gene, it is more likely to affect males than females because males only have one copy of the gene. This means that even a single mutated copy of the gene can cause the disease in males, while females may be carriers of the mutation and not show any symptoms due to their second normal copy of the gene.

X-linked recessive disorders are more common in males than females because they only have one X chromosome. Examples of X-linked recessive disorders include Duchenne muscular dystrophy, hemophilia, and color blindness. In contrast, X-linked dominant disorders can affect both males and females, but females may have milder symptoms due to their second normal copy of the gene. Examples of X-linked dominant disorders include Rett syndrome and incontinentia pigmenti.

A syndrome, in medical terms, is a set of symptoms that collectively indicate or characterize a disease, disorder, or underlying pathological process. It's essentially a collection of signs and/or symptoms that frequently occur together and can suggest a particular cause or condition, even though the exact physiological mechanisms might not be fully understood.

For example, Down syndrome is characterized by specific physical features, cognitive delays, and other developmental issues resulting from an extra copy of chromosome 21. Similarly, metabolic syndromes like diabetes mellitus type 2 involve a group of risk factors such as obesity, high blood pressure, high blood sugar, and abnormal cholesterol or triglyceride levels that collectively increase the risk of heart disease, stroke, and diabetes.

It's important to note that a syndrome is not a specific diagnosis; rather, it's a pattern of symptoms that can help guide further diagnostic evaluation and management.

Sequence Tagged Sites (STSs) are specific, defined DNA sequences that are mapped to a unique location in the human genome. They were developed as part of a physical mapping strategy for the Human Genome Project and serve as landmarks for identifying and locating genetic markers, genes, and other features within the genome. STSs are typically short (around 200-500 base pairs) and contain unique sequences that can be amplified by PCR, allowing for their detection and identification in DNA samples. The use of STSs enables researchers to construct physical maps of large genomes with high resolution and accuracy, facilitating the study of genome organization, variation, and function.

DNA transposable elements, also known as transposons or jumping genes, are mobile genetic elements that can change their position within a genome. They are composed of DNA sequences that include genes encoding the enzymes required for their own movement (transposase) and regulatory elements. When activated, the transposase recognizes specific sequences at the ends of the element and catalyzes the excision and reintegration of the transposable element into a new location in the genome. This process can lead to genetic variation, as the insertion of a transposable element can disrupt the function of nearby genes or create new combinations of gene regulatory elements. Transposable elements are widespread in both prokaryotic and eukaryotic genomes and are thought to play a significant role in genome evolution.

Recessive genes refer to the alleles (versions of a gene) that will only be expressed when an individual has two copies of that particular allele, one inherited from each parent. If an individual inherits one recessive allele and one dominant allele for a particular gene, the dominant allele will be expressed and the recessive allele will have no effect on the individual's phenotype (observable traits).

Recessive genes can still play a role in determining an individual's genetic makeup and can be passed down through generations even if they are not expressed. If two carriers of a recessive gene have children, there is a 25% chance that their offspring will inherit two copies of the recessive allele and exhibit the associated recessive trait.

Examples of genetic disorders caused by recessive genes include cystic fibrosis, sickle cell anemia, and albinism.

A lethal gene is a type of gene that causes the death of an organism or prevents it from surviving to maturity. This can occur when the gene contains a mutation that disrupts the function of a protein essential for the organism's survival. In some cases, the presence of two copies of a lethal gene (one inherited from each parent) can result in a condition that is incompatible with life, and the organism will not survive beyond embryonic development or shortly after birth.

Lethal genes can also contribute to genetic disorders, where the disruption of protein function caused by the mutation leads to progressive degeneration and ultimately death. In some cases, lethal genes may only cause harm when expressed in certain tissues or at specific stages of development, leading to a range of phenotypes from embryonic lethality to adult-onset disorders.

It's important to note that the term "lethal" is relative and can depend on various factors such as genetic background, environmental conditions, and the presence of modifier genes. Additionally, some lethal genes may be targeted for gene editing or other therapeutic interventions to prevent their harmful effects.

Bacterial DNA refers to the genetic material found in bacteria. It is composed of a double-stranded helix containing four nucleotide bases - adenine (A), thymine (T), guanine (G), and cytosine (C) - that are linked together by phosphodiester bonds. The sequence of these bases in the DNA molecule carries the genetic information necessary for the growth, development, and reproduction of bacteria.

Bacterial DNA is circular in most bacterial species, although some have linear chromosomes. In addition to the main chromosome, many bacteria also contain small circular pieces of DNA called plasmids that can carry additional genes and provide resistance to antibiotics or other environmental stressors.

Unlike eukaryotic cells, which have their DNA enclosed within a nucleus, bacterial DNA is present in the cytoplasm of the cell, where it is in direct contact with the cell's metabolic machinery. This allows for rapid gene expression and regulation in response to changing environmental conditions.

Tumor suppressor genes are a type of gene that helps to regulate and prevent cells from growing and dividing too rapidly or in an uncontrolled manner. They play a critical role in preventing the formation of tumors and cancer. When functioning properly, tumor suppressor genes help to repair damaged DNA, control the cell cycle, and trigger programmed cell death (apoptosis) when necessary. However, when these genes are mutated or altered, they can lose their ability to function correctly, leading to uncontrolled cell growth and the development of tumors. Examples of tumor suppressor genes include TP53, BRCA1, and BRCA2.

Occupational diseases are health conditions or illnesses that occur as a result of exposure to hazards in the workplace. These hazards can include physical, chemical, and biological agents, as well as ergonomic factors and work-related psychosocial stressors. Examples of occupational diseases include respiratory illnesses caused by inhaling dust or fumes, hearing loss due to excessive noise exposure, and musculoskeletal disorders caused by repetitive movements or poor ergonomics. The development of an occupational disease is typically related to the nature of the work being performed and the conditions in which it is carried out. It's important to note that these diseases can be prevented or minimized through proper risk assessment, implementation of control measures, and adherence to safety regulations.

Gene duplication, in the context of genetics and genomics, refers to an event where a segment of DNA that contains a gene is copied, resulting in two identical copies of that gene. This can occur through various mechanisms such as unequal crossing over during meiosis, retrotransposition, or whole genome duplication. The duplicate genes are then passed on to the next generation.

Gene duplications can have several consequences. Often, one copy may continue to function normally while the other is free to mutate without affecting the organism's survival, potentially leading to new functions (neofunctionalization) or subfunctionalization where each copy takes on some of the original gene's roles.

Gene duplication plays a significant role in evolution by providing raw material for the creation of novel genes and genetic diversity. However, it can also lead to various genetic disorders if multiple copies of a gene become dysfunctional or if there are too many copies, leading to an overdose effect.

DNA Mutational Analysis is a laboratory test used to identify genetic variations or changes (mutations) in the DNA sequence of a gene. This type of analysis can be used to diagnose genetic disorders, predict the risk of developing certain diseases, determine the most effective treatment for cancer, or assess the likelihood of passing on an inherited condition to offspring.

The test involves extracting DNA from a patient's sample (such as blood, saliva, or tissue), amplifying specific regions of interest using polymerase chain reaction (PCR), and then sequencing those regions to determine the precise order of nucleotide bases in the DNA molecule. The resulting sequence is then compared to reference sequences to identify any variations or mutations that may be present.

DNA Mutational Analysis can detect a wide range of genetic changes, including single-nucleotide polymorphisms (SNPs), insertions, deletions, duplications, and rearrangements. The test is often used in conjunction with other diagnostic tests and clinical evaluations to provide a comprehensive assessment of a patient's genetic profile.

It is important to note that not all mutations are pathogenic or associated with disease, and the interpretation of DNA Mutational Analysis results requires careful consideration of the patient's medical history, family history, and other relevant factors.

Histones are highly alkaline proteins found in the chromatin of eukaryotic cells. They are rich in basic amino acid residues, such as arginine and lysine, which give them their positive charge. Histones play a crucial role in packaging DNA into a more compact structure within the nucleus by forming a complex with it called a nucleosome. Each nucleosome contains about 146 base pairs of DNA wrapped around an octamer of eight histone proteins (two each of H2A, H2B, H3, and H4). The N-terminal tails of these histones are subject to various post-translational modifications, such as methylation, acetylation, and phosphorylation, which can influence chromatin structure and gene expression. Histone variants also exist, which can contribute to the regulation of specific genes and other nuclear processes.

Sequence homology in nucleic acids refers to the similarity or identity between the nucleotide sequences of two or more DNA or RNA molecules. It is often used as a measure of biological relationship between genes, organisms, or populations. High sequence homology suggests a recent common ancestry or functional constraint, while low sequence homology may indicate a more distant relationship or different functions.

Nucleic acid sequence homology can be determined by various methods such as pairwise alignment, multiple sequence alignment, and statistical analysis. The degree of homology is typically expressed as a percentage of identical or similar nucleotides in a given window of comparison.

It's important to note that the interpretation of sequence homology depends on the biological context and the evolutionary distance between the sequences compared. Therefore, functional and experimental validation is often necessary to confirm the significance of sequence homology.

Exons are the coding regions of DNA that remain in the mature, processed mRNA after the removal of non-coding intronic sequences during RNA splicing. These exons contain the information necessary to encode proteins, as they specify the sequence of amino acids within a polypeptide chain. The arrangement and order of exons can vary between different genes and even between different versions of the same gene (alternative splicing), allowing for the generation of multiple protein isoforms from a single gene. This complexity in exon structure and usage significantly contributes to the diversity and functionality of the proteome.

Uniparental disomy (UPD) is a chromosomal abnormality where an individual receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent. This occurs when there is an error in gamete formation, such as nondisjunction or segregation defects during meiosis, resulting in the production of gametes with abnormal numbers of chromosomes.

There are two types of UPD: heterodisomy and isodisomy. Heterodisomy occurs when an individual receives two different copies of a chromosome from one parent, while isodisomy occurs when an individual receives two identical copies of a chromosome from one parent.

UPD can have significant genetic consequences, particularly if the affected chromosome contains imprinted genes, which are genes that are expressed differently depending on whether they are inherited from the mother or father. UPD can lead to abnormal gene expression and may result in developmental disorders, growth abnormalities, and increased risk of certain diseases, such as Prader-Willi syndrome and Angelman syndrome.

It is important to note that UPD is a rare event and occurs in less than 1% of the population. However, it can have serious health consequences, and genetic counseling and testing may be recommended for individuals with a family history of chromosomal abnormalities or developmental disorders.

Gene expression profiling is a laboratory technique used to measure the activity (expression) of thousands of genes at once. This technique allows researchers and clinicians to identify which genes are turned on or off in a particular cell, tissue, or organism under specific conditions, such as during health, disease, development, or in response to various treatments.

The process typically involves isolating RNA from the cells or tissues of interest, converting it into complementary DNA (cDNA), and then using microarray or high-throughput sequencing technologies to determine which genes are expressed and at what levels. The resulting data can be used to identify patterns of gene expression that are associated with specific biological states or processes, providing valuable insights into the underlying molecular mechanisms of diseases and potential targets for therapeutic intervention.

In recent years, gene expression profiling has become an essential tool in various fields, including cancer research, drug discovery, and personalized medicine, where it is used to identify biomarkers of disease, predict patient outcomes, and guide treatment decisions.

An acute disease is a medical condition that has a rapid onset, develops quickly, and tends to be short in duration. Acute diseases can range from minor illnesses such as a common cold or flu, to more severe conditions such as pneumonia, meningitis, or a heart attack. These types of diseases often have clear symptoms that are easy to identify, and they may require immediate medical attention or treatment.

Acute diseases are typically caused by an external agent or factor, such as a bacterial or viral infection, a toxin, or an injury. They can also be the result of a sudden worsening of an existing chronic condition. In general, acute diseases are distinct from chronic diseases, which are long-term medical conditions that develop slowly over time and may require ongoing management and treatment.

Examples of acute diseases include:

* Acute bronchitis: a sudden inflammation of the airways in the lungs, often caused by a viral infection.
* Appendicitis: an inflammation of the appendix that can cause severe pain and requires surgical removal.
* Gastroenteritis: an inflammation of the stomach and intestines, often caused by a viral or bacterial infection.
* Migraine headaches: intense headaches that can last for hours or days, and are often accompanied by nausea, vomiting, and sensitivity to light and sound.
* Myocardial infarction (heart attack): a sudden blockage of blood flow to the heart muscle, often caused by a buildup of plaque in the coronary arteries.
* Pneumonia: an infection of the lungs that can cause coughing, chest pain, and difficulty breathing.
* Sinusitis: an inflammation of the sinuses, often caused by a viral or bacterial infection.

It's important to note that while some acute diseases may resolve on their own with rest and supportive care, others may require medical intervention or treatment to prevent complications and promote recovery. If you are experiencing symptoms of an acute disease, it is always best to seek medical attention to ensure proper diagnosis and treatment.

A genetic locus (plural: loci) is a specific location on a chromosome where a particular gene or DNA sequence is found. It is the precise position where a specific genetic element, such as a gene or marker, is located on a chromsomere. This location is defined in terms of its relationship to other genetic markers and features on the same chromosome. Genetic loci can be used in linkage and association studies to identify the inheritance patterns and potential relationships between genes and various traits or diseases.

The Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer is a free access database devoted to chromosomes, ... It was first published in 1983 as a book named "Catalog of Chromosome aberrations in Cancer" in the Journal of Cytogenetics and ... ISBN 0-8451-4248-8. Mitelman, Felix (1991). Catalog of chromosome aberrations in cancer (4th ed.). New York: Wiley-Liss. p. ... ISBN 0-471-56087-1. Mitelman, Felix (1994). Catalog of chromosome aberrations in cancer (5th ed.). New York: Wiley-Liss. p. ...
DNA and chromosome aberrations; structural biology and molecular applications; tumor biology and microenvironment; and tumor ...
Douglas RN, Birchler JA (2017). "B Chromosomes". In Bhat T, Wani A (eds.). Chromosome Structure and Aberrations. New Delhi: ... Discussing B chromosomes in plants he wrote: In many cases these chromosomes have no useful function at all to the species ... B chromosomes refer to chromosomes that are not required for the viability or fertility of the organism, but exist in addition ... B chromosomes were first detected over a century ago.[when?] Though typically smaller than normal chromosomes, their gene poor ...
Mertens, F.; Wahlberg, P.; Domanski, H. A. (2009). "Clonal chromosome aberrations in a sialoblastoma". Cancer Genetics and ...
August 2006). "Stochastic cancer progression driven by non-clonal chromosome aberrations". Journal of Cellular Physiology. 208 ... "Cancer progression by non-clonal chromosome aberrations". Journal of Cellular Biochemistry. 98 (6): 1424-1435. doi:10.1002/jcb. ... and karyotypic variations including chromosome structural aberrations and aneuploidy. Studies of this issue have focused mainly ... Advances in cytogenetics facilitated discovery of chromosome abnormalities in neoplasms, including the Philadelphia chromosome ...
"Mitelman Database of Chromosome Aberrations in Cancer". Cancer Genome Anatomy Project. Retrieved 2008-03-01. v t e (Articles ... See below.) Mitelman F: Catalog of Chromosome Aberrations in Cancer, Karger, Basel 1983, ISBN 3-8055-3813-8; 2nd Ed. Alan R. ... Mitelman, F; Johansson, B; Mertens, F (2004). "Fusion genes and rearranged genes as a linear function of chromosome aberrations ... Together with Fredrik Mertens and Bertil Johansson he maintains a database of all published chromosome aberrations in ...
... in humans two chromosomes fused to form chromosome 2. Chromosomal aberrations are disruptions in the normal chromosomal content ... Chromosomes can also be fused artificially. For example, the 16 chromosomes of yeast have been fused into one giant chromosome ... Chromosomes in humans can be divided into two types: autosomes (body chromosome(s)) and allosome (sex chromosome(s)). Certain ... and two sex chromosomes. This gives 46 chromosomes in total. Other organisms have more than two copies of their chromosome ...
Henry H.Q. Heng (2006-05-10). "Stochastic cancer progression driven by non-clonal chromosome aberrations". Journal of Cellular ... "chromosome catastrophes," "structural mutations," "Frankenstein chromosomes," and more). Despite the various individual ... the idea that there is an emergent level of information from the order of genes on a chromosome, two-phased evolution, a model ... The Genome Architecture Theory focuses more on a genome or chromosome-oriented approach to biology, in contrast to the ...
The Cancer Chromosome Aberration Project (cCAP) is a CGAP supported initiative used for defining chromosome structure and to ... "The Cancer Chromosome Aberration Project (CCAP)". Retrieved 2014-09-05. "All About the FISH-mapped BACs". Retrieved 2014-09-07 ... with notable ones including the Cancer Chromosome Aberration Project (CCAP) and the Genetic Annotation Initiative (GAI). CGAP ... U. Brinkmann; G. Vasmatzis; B. Lee; N. Yerushalmi; M. Essand; I. Pastan (September 1998). "PAGE-1, an X chromosome-linked GAGE- ...
"Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". cgap.nci.nih.gov. Retrieved 2018-11-27. Nathanson, ... Fikes, Bradley J. (9 February 2017). "Cancer genes hide outside chromosomes". sandiegouniontribune.com. Retrieved 2019-01-31. " ...
"Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". Archived from the original on 2016-05-29. "Atlas of ... When the chromosome's structure is altered, this can take several forms: Deletions: A portion of the chromosome is missing or ... Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a ... An abnormal number of chromosomes is known as aneuploidy, and occurs when an individual is either missing a chromosome from a ...
"Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". Archived from the original on 2016-05-25. Retrieved ... Laâbi Y, Gras MP, Carbonnel F, Brouet JC, Berger R, Larsen CJ, Tsapis A (November 1992). "A new gene, BCM, on chromosome 16 is ... September 1999). "Genome duplications and other features in 12 Mb of DNA sequence from human chromosome 16p and 16q". Genomics ... Genes on human chromosome 16, Articles containing potentially dated statements from June 2021, All articles containing ...
"Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". Archived from the original on 2016-05-29. "Atlas of ... Loss of heterozygocity on chromosome arm 3p is found in more than 80% of SCLCs, including the loss of FHIT. One hundred ...
August 2002). "Further case of Cantú syndrome: exclusion of cryptic subtelomeric chromosome aberrations". Am. J. Med. Genet. ... This second gene is also located on the short arm of chromosome 12 (12p12.1).[citation needed] In terms of the mechanism of ... The gene is located on short arm of chromosome 12 (12p12). Mutations in another gene (KCNJ8) has also been associated with this ...
10] Chromosome connections and aberrations in the Campanula persicifolia group. Svensk Botanisk Tidskrift 58: 1-17. 1964. ... Chromosome numbers of some Arctic or boreal flowering plants. Meddelelser om Grønland 147, 6: 1-32. 1950. Contributions to the ... Keywords: algae, Greenland' Chromosome behaviour and syncyte formation in Phleum phleoides (L.) Karst. Botaniska Notiser 1950: ... Chromosome studies in the Ranunculus polyanthemus complex. Botanisk Tidsskrift 54: 160-166. 1958. & M.W. Bentzon. Density ...
Luippold HE, Gooch PC, Brewen JG (February 1978). "The production of chromosome aberrations in various mammalian cells by ... It can cause chromatid aberrations in cell models. Altretamine Wong JR, Morton LM, Tucker MA, Abramson DH, Seddon JM, Sampson ...
Mitelman F; Johansson B; Mertens F. "Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". Archived from the ... This database is called Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer. Presence of certain chromosomal ... part of the ABL1 gene in the breakpoint on chromosome 9 and the 5' part of a gene called BCR in the breakpoint in chromosome 22 ... later designated the Philadelphia chromosome. In 1973, Janet Rowley in Chicago showed that the Philadelphia chromosome had ...
It seems that they are easy to analyze compared to chromosome aberrations. Umbreit, Neil T.; Zhang, Cheng-Zhong; Lynch, Luke D ... If the cell senses extra chromosomes, the cell can attempt to remove the extra chromosome in another cell membrane, separate ... This results in parts of the chromatids or chromosomes being broken off and enveloped as an extra nucleus in one of the ... Micronuclei can contain a whole chromosome or part of a chromatid. The increased formation of micronuclei is usually an ...
... are rare aberrations of human chromosome 1. In a common situation a human cell has one pair of identical chromosomes on ... In this way the number of chromosomes will be halved in each cell, while all the parts on the chromosome (genes) remain, after ... chromosome 1. With the 1q21.1 CNVs one chromosome of the pair is not complete because a part of the sequence of the chromosome ... The result is that one chromosome is of normal length and the other one is too long or too short.[citation needed] The ...
"Effect of epithalon on the incidence of chromosome aberrations in senescence-accelerated mice". Bull Exp Biol Med. 133 (3): 274 ... epitalon did not appear to correct pre-existing structural aberrations of chromosomes associated with telomere degradation, but ... An in vivo study in aging mice found that epitalon treatment significantly reduced the incidence of chromosomal aberrations, ... did appear to exert a protective effect against the future development of additional chromosomal aberrations. A human ...
Polycentric chromosomes are produced by chromosomal aberrations such as deletion, duplication, or translocation.[citation ... In genetics, a polycentric chromosome is any chromosome featuring multiple centromeres. ... Polycentric chromosomes usually result in the death of the cell because polycentric chromosomes may fail to move to opposite ... As a result, the chromosome is fragmented, which causes the death of the cell. In some algae, such as Spirogyra, polycentric ...
... is a rare aberration of chromosome 1. A human cell has one pair of identical chromosomes on chromosome ... One chromosome has the normal length and the other is too short. In 1q21.1, the '1' stands for chromosome 1, the 'q' stands for ... 2009). "BAC array CGH in patients with Velocardiofacial syndrome-like features reveals genomic aberrations on chromosome region ... This deletion affects one of each cell's two copies of chromosome 1. The symptoms caused by a 1q21.1 microdeletion are most ...
Genetic Broadly speaking, genetic diseases are caused by aberrations in genes or chromosomes. Many genetic diseases are ...
This technique works well in recognizing HeLa because these cells have distinctive chromosome aberrations. Novel cell lines are ...
2011). "Chromosome Segregation Errors as a cause of DNA Damage and Structural Chromosome Aberrations". Science. 333 (6051): ... Cells with defective chromosome segregation will form micronuclei which contain whole chromosomes or fragments of chromosomes. ... Chromosome segregation errors can lead to DNA damage and chromosomal aberrations such as aneuploidy which is linked to tumour ... The resulting fragmented chromosome segments can be joined together to give rise to a rearranged chromosome, which can ...
"Sensitive detection of chromosome copy number aberrations in prostate cancer by fluorescence in situ hybridization". The ... X chromosome reactivation (XCR) is the process by which the inactive X chromosome (the Xi) is re-activated in the cells of ... July 2015). "Chromosomes. A comprehensive Xist interactome reveals cohesin repulsion and an RNA-directed chromosome ... Therian female mammalian cells have two X chromosomes, while males have only one, requiring X-chromosome inactivation (XCI) for ...
Abe, Syuiti; Sasaki, Motomichi (1977). "Chromosome Aberrations and Sister Chromatid Exchanges in Chinese Hamster Cells Exposed ...
These DNA damages, chromosome aberrations and mutations may in turn cause more RecQ-independent aging phenotypes.[citation ... Mouse cells deficient for maturation of prelamin A show increased DNA damage and chromosome aberrations and have increased ... Cells of affected individuals have reduced lifespan in culture, more chromosome breaks and translocations and extensive ...
Molecular mechanisms of the origin of chromosome aberrations and the structural organization of eukaryotic DNA. Theor. Appl. ... Chromosome breakage and complete genic mutation production in molecular terms. Mutation Res., v. 8, pp. 353-365. (In English); ... Repair of single-strand DNA breaks and recovery of chromosomal and chromatid aberrations after treatment of plant seeds with ... found the first evidence that induction of chromatid and chromosomal aberrations in higher plants is triggered by single-strand ...
In mice, X-ray induced chromosome aberrations were reduced when cinnamaldehyde was given orally to the mice after X-ray ... and anisaldehyde on chromosome aberrations induced by X-rays in mice". Mutation Research. 243 (4): 299-302. doi:10.1016/0165- ...
The Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer is a free access database devoted to chromosomes, ... It was first published in 1983 as a book named "Catalog of Chromosome aberrations in Cancer" in the Journal of Cytogenetics and ... ISBN 0-8451-4248-8. Mitelman, Felix (1991). Catalog of chromosome aberrations in cancer (4th ed.). New York: Wiley-Liss. p. ... ISBN 0-471-56087-1. Mitelman, Felix (1994). Catalog of chromosome aberrations in cancer (5th ed.). New York: Wiley-Liss. p. ...
Furthermore, the RBE values for the induction of the two types of chromosome aberrations are similar to those establ … ... Chromosome aberration frequencies were determined by scoring fragments and translocations using premature chromosome ... Comparison of RBE values of high-LET α-particles for the induction of DNA-DSBs, chromosome aberrations and cell reproductive ... Furthermore, the RBE values for the induction of the two types of chromosome aberrations are similar to those established for ...
Patterns of chromosome abnormality: The key to cancer?. , January 24, 2012 , 0 responses ... A healthy genome is characterized by 23 pairs of chromosomes, and even a small change in this structure - such as an extra copy ... of a single chromosome - can lead to severe physical impairment. So it\s no surprise that when it comes to cancer, chromosomal ...
Mitelman, F. 1994: Catalog of chromosome aberrations in cancer, Fifth edition Chromosomes 1-12 Chromosomes 13-22, X, Y Mitelman ... Mitelman, F. 1991: Catalog of chromosome aberrations in cancer fourth edition chromosomes 1 12 chromosomes 13 22 x y references ... F Catalog of chromosome aberrations in cancer, Fifth edition: Chromosomes 1-12 (Part 1) Chromosomes 13-22, X, Y (Part 2) xxix+ ... F Catalog Of Chromosome Aberrations in Cancer, Fourth Edition; Chromosomes 1-12; Chromosomes 13-22, X, Y, References Xxxiv+998p ...
Gain of chromosome 1, the aberration most often seen in VIN III (67%), was not seen in HPV-positive or -negative VSCCs (0%). ... The most common chromosome aberration detected by high-resolution comparative genomic hybridization in vulvar intraepithelial ...
Herbert, Anthony (1982) Sister chromatid exchange and chromosome aberrations in human lymphocytes vs point-mutational damage in ... Sister chromatid exchange and chromosome aberrations in human lymphocytes vs point-mutational damage in bacteria : a study ... Sister chromatid exchange and chromosome aberrations in human lymphocytes vs point-mutational damage in bacteria : a study ... Sister chromatid exchange and chromosome aberrations in human lymphocytes vs point-mutational damage in bacteria : a study ...
Genotoxicity Testing of Neem Plant (Azadirachta indica A. Juss.) Using the Allium cepa Chromosome Aberration Assay. Journal of ... Genotoxicity Testing of Neem Plant (Azadirachta indica A. Juss.) Using the Allium cepa Chromosome Aberration Assay table, th, ...
... ... dose-response relationship by the method of maximum-likelihood and estimating a dose from the number of aberrations observed ...
Aberrations involving the number 5 chromosomes were identified using mBAND. Exchanges involving aberrant chromosomes 5 were ... Characterisation and transmissibility of α-particle-induced chromosome aberrations. J. Tawn1, C. Whitehouse2 and H. Thierens3 ... In recent years, in vitro studies have highlighted the complexity of chromosome aberrations induced by α-irradiation. Moreover ... the relationship between chromosome aberration frequencies in blood lymphocytes and dose is more difficult to establish. ...
... next-generation sequencing and arrays enable cytogenomic analysis of chromosome aberrations for constitutional and cancer ... Understanding chromosome aberrations through cytogenetic analysis is an integral part of current genomic medicine, playing a ... Illumina offers high-quality microarrays designed to detect chromosome aberrations and provide accurate, reliable cytogenomic ... Cytogenomic microarrays offer a simple, reliable method for assessing chromosomal aberrations at a higher resolution. ...
It was long believed that there were 48 chromosomes in total, but no one was sure because it was difficult to obtain good ... Albert Levan, a researcher at Lund University, was the first to establish how many chromosomes there are in the human genome. ...
Kromosoomide ebanormaalne struktuur või nende arvu muutus rakus. Näiteks kromosoomsed puudujäägid (deletsioonid), duplikatsioonid, inversioonid, translokatsioonid, aneuploidsus, polüploidsus jt.. ...
DNA and Chromosome Aberrations Branch. This branch administers extramural grants for studies in cancer genetics and epigenetics ...
The information in the Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer relates cytogenetic changes and ... The Clinical Associations Searcher searches studies pertaining to clinical associations of cytogenetic aberrations and/or gene ...
Genes Chromosomes Cancer 58: 607-611, 2019.. Mitelman F, Johansson B, Mertens F, Schyman T, Mandahl N. Cancer chromosome ... The Database of Chromosome Aberrations and Gene Fusions in Cancer, established in 1980, is an attempt to register ... the role chromosome aberrations play in the formation of fusion genes, and the mechanisms by which gene fusions exert their ... Genes Chromosomes Cancer 55:291-310, 2016.. Mertens F, Johansson B, Fioretos T, Mitelman F. The emerging complexity of gene ...
Genes Chromosomes Cancer 58: 607-611, 2019.. Mitelman F, Johansson B, Mertens F, Schyman T, Mandahl N. Cancer chromosome ... The Database of Chromosome Aberrations and Gene Fusions in Cancer, established in 1980, is an attempt to register ... the role chromosome aberrations play in the formation of fusion genes, and the mechanisms by which gene fusions exert their ... Genes Chromosomes Cancer 55:291-310, 2016.. Mertens F, Johansson B, Fioretos T, Mitelman F. The emerging complexity of gene ...
These results strongly suggest that NS is mainly caused by structural aberrations in the nucleus during interphase of the cell ... Since nuclear swelling (NS hereafter) has been frequently observed in chromosomal aberration (CA hereafter) tests (in vitro), ... Table 2 Clastogens induced chromosome aberrations and nuclear swelling in CHL cells. Full size table. ... Takeshita, K., Ogawa, H.I. & Maeda, T. Structural chromosome aberrations cause swelling of the nucleus. Genes and Environ 38, ...
... but that they were associated with either chromosome aberrations or normal chromosome profiles. Multiple imprinted methylation ... Both Epimutations and Chromosome Aberrations Affect Multiple Imprinted Loci in Aggressive Wilms Tumors. Authors: L. Pignata, O ... Both Epimutations and Chromosome Aberrations Affect Multiple Imprinted Loci in Aggressive Wilms Tumors ... Link: Both Epimutations and Chromosome Aberrations Affect Multiple Imprinted Loci in Aggressive Wilms Tumors ...
A proposed system for scoring structural aberrations detected by chromosome painting. J. D. Tucker, W. F. Morgan, A. A. Awa, M ... The advent of chromosome painting has brought the realization that structural aberrations can be far more complicated than ... A proposed system for scoring structural aberrations detected by chromosome painting. / Tucker, J. D.; Morgan, W. F.; Awa, A. A ... A proposed system for scoring structural aberrations detected by chromosome painting. Cytogenetics and Cell Genetics. 1995;68(3 ...
Associated defects and complications - Generally unknown; potential chromosome aberrations. * Clinical considerations: There ... Studies have demonstrated less-than-normal numbers of chromosomes and damage to the structure of chromosomes in the sperm of ...
Cells containing aberrations involving painted chromosomes (FISH aberrations) were further classified according to cell ... to paint chromosomes 1, 3 and 5. The whole genome was analyzed for unstable aberrations to derive aberration frequencies and ... The Characterization and Transmissibility of Chromosome Aberrations Induced in Peripheral Blood Lymphocytes by In Vitro α- ... The Characterization and Transmissibility of Chromosome Aberrations Induced in Peripheral Blood Lymphocytes by In Vitro α- ...
SKY and FISH analysis of radiation-induced chromosome aberrations: A comparison of whole and partial genome analysis ... SKY and FISH analysis of radiation-induced chromosome aberrations: A comparison of whole and partial genome analysis. Mutation ...
... in humans two chromosomes fused to form chromosome 2. Aberrations[edit]. In Down syndrome, there are three copies of chromosome ... Human chromosomes[edit]. Chromosomes in humans can be divided into two types: autosomes (body chromosome(s)) and allosome (sex ... Chromosome numbers in other organisms Species. Large. chromosomes. Intermediate. chromosomes. Microchromosomes Trypanosoma ... Chromosomes can also be fused artificially. For example, the 16 chromosomes of yeast have been fused into one giant chromosome ...
DNA cytometry and chromosome 9 aberrations by fluorescence in situ hybridization of irrigation specimens from bladder cancer ... DNA cytometry and chromosome 9 aberrations by fluorescence in situ hybridization of irrigation specimens from bladder cancer ... DNA cytometry and chromosome 9 aberrations by fluorescence in situ hybridization of irrigation specimens from bladder cancer ... DNA cytometry and chromosome 9 aberrations by fluorescence in situ hybridization of irrigation specimens from bladder cancer ...
"Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer". cgap.nci.nih.gov. Retrieved 2018-11-27. Nathanson, ... Fikes, Bradley J. (9 February 2017). "Cancer genes hide outside chromosomes". sandiegouniontribune.com. Retrieved 2019-01-31. " ...
We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after ... We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after ... We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after ... We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after ...
CNAs of chromosomes 7, 13q, 18 and 20q. Focal aberrations (≤10 Mbp) were mapped to chromosome bands 6p22.1-p21.33 (33.3%), ... The entire 8q chromosome (minimum corrected p-value: q = 0.0001) and chromosome 20q13.2 including the ZNF217 locus (q = 0.0078 ... The number of chromosomes ranges from 45 to 90. FDOV1 cells produces CA-125, but not CA-199. The cells could be transplanted ... chromosome 20q13) amplification in FDOV1, which are quite novel.. CONCLUSIONS: Only a few patient-derived ovarian clear cell ...
Chromosome Aberrations Negative *Mouse Lymphoma (G16413) Completed *Citation: Myhr BC, Caspary WJ. Evaluation of the L5178Y ...
  • The sensitivity, accuracy and feasibility of application of SCE as an in vitro screening test has been evaluated against cytogenetic aberrations and the Ames test. (soton.ac.uk)
  • In recent years, in vitro studies have highlighted the complexity of chromosome aberrations induced by α-irradiation. (radioprotection.org)
  • Lymphocytes in their first in vitro division following exposure to 213Bi α-particles were analysed by sFISH and genomic aberration frequencies derived. (radioprotection.org)
  • Since nuclear swelling (NS hereafter) has been frequently observed in chromosomal aberration (CA hereafter) tests (in vitro), the relationship between NS and CAs was investigated in this study. (biomedcentral.com)
  • An in vitro mammalian chromosome aberration test was performed with the test substance in Chinese hamster V79 cells according to OECD guideline 473 and in compliance with GLP (Oppong-Nketiah, 2012). (europa.eu)
  • A method is proposed to allow quantitative estimates to be made of mutation frequency.The induction of SCE and cytogenetic aberrations in human lymphocytes and point-mutation in Salmonella has been investigated following exposure to a range of selected direct-acting chemical mutagens. (soton.ac.uk)
  • The Clinical Associations Searcher searches studies pertaining to clinical associations of cytogenetic aberrations and/or gene rearrangements. (isb-cgc.org)
  • The Database of Chromosome Aberrations and Gene Fusions in Cancer, established in 1980, is an attempt to register systematically all published cytogenetic aberrations reported in cancer, including patient and tumor characteristics, gene fusions identified by cytogenetics or massively parallel sequencing, and studies pertaining to the clinical relevance of cytogenetic aberrations and/or gene rearrangements. (lu.se)
  • The database represents a unique international resource that enables clinicians to quickly find relevant information on cytogenetic aberrations and gene fusions in cancer and relate the findings to clinical data, in particular the diagnostic and prognostic significance of specific cytogenetic/genomic changes. (lu.se)
  • For high LET irradiation, such as that from internally deposited α-emitting radionuclides, the relationship between chromosome aberration frequencies in blood lymphocytes and dose is more difficult to establish. (radioprotection.org)
  • Chromosome Aberrations in Peripheral Lymphocytes of College Students as a Response to Photochemical Air Pollution. (epa.gov)
  • Chromosome aberrations in lymphocytes of workers exposed to styrene. (sjweh.fi)
  • The continuously updated material also makes it possible to address scientific questions related to the mechanisms through which chromosomal/genomic changes participate in the carcinogenic process by elucidating why, how and when chromosome abnormalities are formed, the chromosomal anatomy of cytogenetic changes and genes involved in fusions, the role chromosome aberrations play in the formation of fusion genes, and the mechanisms by which gene fusions exert their effects. (lu.se)
  • The results demonstrated that methylation abnormalities of multiple imprinted loci occurred in 35% of the cases, but that they were associated with either chromosome aberrations or normal chromosome profiles. (sequentiabiotech.com)
  • The positive controls showed the expected increase in the rate of chromosome aberrations, thus indicating the sensitivity of the assay. (europa.eu)
  • Blood samples were collected and processed for a dicentric chromosome assay. (springer.com)
  • Cell stability status was established by analysing the whole genome for unstable aberrations. (radioprotection.org)
  • The whole genome was analyzed for unstable aberrations to derive aberration frequencies and determine cell stability. (bioone.org)
  • Chromosome analysis was performed on 47-h cultures using single-color fluorescence in situ hybridization (FISH) to paint chromosomes 1, 3 and 5. (bioone.org)
  • Objectives: To determine the sensitivity and specificity of combining fluorescence in situ hybridization (FISH) measurement of chromosome 9 and DNA cytometry of bladder irrigation specimens in the detection of bladder cancer. (johnshopkins.edu)
  • High hyperdiploid acute lymphoblastic leukemia (HeH ALL), one of the most common childhood malignancies, is driven by nonrandom aneuploidy (abnormal chromosome numbers) mainly comprising chromosomal gains. (lu.se)
  • Hematological disorders are typically associated with hematopoietic stem cells mutations and chromosomal aberrations such as aneuploidy or euploidy ( Zagozdzon and Golab, 2015 ZAGOZDZON, R. and GOLAB, J., 2015. (scielo.br)
  • It was first published in 1983 as a book named "Catalog of Chromosome aberrations in Cancer" in the Journal of Cytogenetics and Cell Genetics, containing 3,844 cases. (wikipedia.org)
  • The database is available on-line (https://mitelmandatabase.isb-cgc.org) for searches related to cases cytogenetics, gene fusions, clinical associations, structural or numerical recurrent aberrations and references. (wikipedia.org)
  • The information in the Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer relates cytogenetic changes and their genomic consequences, in particular gene fusions, to tumor characteristics, based either on individual cases or associations. (wikipedia.org)
  • Mitelman F, Johansson B, Mertens F, Schyman T, Mandahl N. Cancer chromosome breakpoints cluster in gene-rich genomic regions. (lu.se)
  • These data demonstrate the presence of cells in irrigation specimens with specific genomic lesions of chromosome 9 and DNA content. (johnshopkins.edu)
  • A healthy genome is characterized by 23 pairs of chromosomes, and even a small change in this structure - such as an extra copy of a single chromosome - can lead to severe physical impairment. (world.edu)
  • Albert Levan, a researcher at Lund University, was the first to establish how many chromosomes there are in the human genome. (lu.se)
  • ORCID: https://orcid.org/0000-0001-7042-0308 , Eder, C , Muller, I , Figel, M and Zitzelsberger, H (2005) SKY and FISH analysis of radiation-induced chromosome aberrations: A comparison of whole and partial genome analysis. (yorksj.ac.uk)
  • Results: Sensitivity of chromosome 9 FISH was 42% for all tumors and was not correlated to transitional cell carcinoma tumor grade, while the sensitivity of DNA cytometry was 55% and improved with increasing grade from 38% for grade 1 to 90% for grade 3 tumors. (johnshopkins.edu)
  • A study carried out at a pilot plant for drinking water disinfection of lake water revealed mutagenic activity of three different disinfectants (sodium hypochlorite, chlorine dioxide and peracetic acid) in different seasons using in situ mutagenicity assays, both in animal (micronucleus test) and in plant organisms (anaphase chromosomal aberration and micronucleus tests). (scirp.org)
  • Therefore plants ( Allium cepa for chromosomal aberration test and Vicia faba for micronucleus test) were exposed to the same disinfected lake-water samples at different temperatures (10℃, 20℃ and 30℃), according the ones registered during the in situ experiment. (scirp.org)
  • Most carcinogens that cause NS are genotoxins, which cause DNA damage, chromosomal aberrations (CAs), and micronucleus formation. (biomedcentral.com)
  • The Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer is a free access database devoted to chromosomes, genes, and cancer. (wikipedia.org)
  • Genes Chromosomes Cancer 58:149-154, 2019. (lu.se)
  • Genes Chromosomes Cancer 55:291-310, 2016. (lu.se)
  • When chromosome profiles were affected, these alterations were extended to flanking cancer driver genes. (sequentiabiotech.com)
  • Non-isolated or syndromic forms of EA/TEF can be caused by changes in single genes or in chromosomes, or they can be multifactorial. (medlineplus.gov)
  • Chromosome aberration frequencies were determined by scoring fragments and translocations using premature chromosome condensation. (nih.gov)
  • Retrospective biodosimetry based on frequencies of chromosome translocations is well established for exposure to low LET radiation and has proved a valuable tool for validating doses in epidemiological studies. (radioprotection.org)
  • Therefore, the quantification of chromosome biomarkers of α-irradiation must take into account the distribution and transmissibility of the different aberration types if it is to provide information that is relevant to the interpretation of in vivo frequencies. (radioprotection.org)
  • DNA intercalation leads to chromosome breakage rather than SCE. (soton.ac.uk)
  • It is observed that both biological effects and epidemiological effects appear to be the same or very similar from ELF exposure and from RF/MW exposures, including calcium ion efflux, melatonin reduction, DNA strand breakage, chromosome aberrations, leukaemia, brain cancer, breast cancer, miscarriage and neurological effects. (whale.to)
  • Patterns of chromosome abnormality: The key to cancer? (world.edu)
  • Evaluation of chromosome 6p22 as a breast cancer risk modifier locus in a follow-up study of BRCA2 mutation carriers. (uniklinikum-dresden.de)
  • [5] In animal cells, chromosomes reach their highest compaction level in anaphase during chromosome segregation . (wikipedia.org)
  • Our results show that, although both investigated radiation types induce similar numbers of IRIF per absorbed dose, only a small fraction of the DSB induced by the low-LET gamma-rays result in chromosome rearrangements and cell reproductive death, while this fraction is considerably enhanced for the high-LET alpha-radiation. (nih.gov)
  • This work has failed to demonstrate a unique chromosome biomarker which would discriminate between different qualities of radiation in workers with historical exposures but has confirmed that stable cells with a single translocation do arise in significant numbers in a dose dependent fashion following α-particle irradiation. (radioprotection.org)
  • A clear and dose-dependent (5.5 and 7.5%, respectively) increase in the rate of chromosomal aberrations compared to negative control was observed at test concentrations of 2000 and 3000 µg/plate without S9 mix. (europa.eu)
  • Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). (wikipedia.org)
  • During metaphase the X-shaped structure is called a metaphase chromosome, which is highly condensed and thus easiest to distinguish and study. (wikipedia.org)
  • He suggested to introduce the term chromosomics being equal to cytogenomics to bring the three-dimensional morphologically of chromosomes into the focus of research, as this is essential for gene regulation. (frontiersin.org)
  • The profile of chromosome damage induced by α-particle irradiation was examined using sFISH and mBAND. (radioprotection.org)
  • We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after irradiation with doses up to 2.5 Gy. (sckcen.be)
  • These results strongly suggest that NS is mainly caused by structural aberrations in the nucleus during interphase of the cell cycle. (biomedcentral.com)
  • The advent of chromosome painting has brought the realization that structural aberrations can be far more complicated than previously imagined. (utmb.edu)
  • These assays can detect mutations in the Tk gene that result from both gene mutations and chromosome damage. (biomedcentral.com)
  • Exchanges involving aberrant chromosomes 5 were classed as inter- or intrachanges and further classified into simple and complex. (radioprotection.org)
  • The proportion of aberrant FISH cells with complex/multiple aberrations ranged from 56% at 10 mGy to 89% at 500 mGy. (bioone.org)
  • To evaluate relationships between DNA-DSB, chromosome aberrations and the clinically most relevant effect of cell reproductive death, for ionizing radiations of different LET, dose-effect relationships were determined for the induction of these effects in cultured SW-1573 cells irradiated with gamma-rays from a Cs-137 source or with α-particles from an Am-241 source. (nih.gov)
  • Furthermore, the RBE values for the induction of the two types of chromosome aberrations are similar to those established for cell reproductive death. (nih.gov)
  • Walter Sutton (left) and Theodor Boveri (right) independently developed the chromosome theory of inheritance in 1902. (wikipedia.org)
  • In his famous textbook The Cell in Development and Heredity , Wilson linked together the independent work of Boveri and Sutton (both around 1902) by naming the chromosome theory of inheritance the Boveri-Sutton chromosome theory (the names are sometimes reversed). (wikipedia.org)
  • Smokers produce sperm with the wrong number of chromosomes, a DNA error that leads to miscarriages and Down Syndrome . (susansmithjones.com)
  • Calculated RBE values derived for the linear components of dose-effect relations for gamma-H2AX foci, cell reproductive death, chromosome fragments and colour junctions are 1.0 ± 0.3, 14.7 ± 5.1, 15.3 ± 5.9 and 13.3 ± 6.0 respectively. (nih.gov)
  • Consequently, a new freely available computer program for fitting a linear-quadratic dose-response relationship by the method of maximum-likelihood and estimating a dose from the number of aberrations observed has been developed by the authors. (europa.eu)
  • A more detailed analysis revealed that the majority of aberrations scored as dicentrics were part of complex/multiple aberrations, with the proportion of cells containing complexes increasing with dose. (bioone.org)
  • DNA double strand breaks (DSB), chromosome aberrations and cell reproductive inactivation. (nih.gov)
  • Aided by the rediscovery at the start of the 1900s of Gregor Mendel 's earlier work, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes. (wikipedia.org)
  • Wilhelm Roux suggested that each chromosome carries a different genetic configuration , and Boveri was able to test and confirm this hypothesis. (wikipedia.org)
  • Combining FISH on chromosome 9 and DNA cytometry provides an in sensitivity to transitional cell carcinoma over either test alone. (johnshopkins.edu)
  • Based on the data on cytotoxicity, concentrations of 1000, 2000, 3000 and 4000 µg/mL in the presence of metabolic activation (S9 mix) and concentrations of 2500, 3750 and 5000 µg/mL in the absence of metabolic activation were used to analyse chromosomal aberrations after exposure to the test substance. (europa.eu)
  • Cells containing aberrations involving painted chromosomes (FISH aberrations) were further classified according to cell stability and complexity. (bioone.org)
  • For the genetic algorithm, see Chromosome (genetic algorithm) . (wikipedia.org)
  • A chromosome is a long DNA molecule with part or all of the genetic material of an organism. (wikipedia.org)
  • Any substance that damages DNA or chromosomes, or changes genetic activity, is genotoxic because it is acting on the same material, i.e. the DNA molecule. (whale.to)
  • Cytogenetic analysis has revealed the presence of chromosomal aberrations of importance in the patient prognosis. (edu.pe)
  • Translocation was the most prevalent 50 (25%), followed by hypotriploidy 14 (7%) and monosomy 8 (4%) on chromosome aberration analysis. (scielo.br)
  • Multiple imprinted methylation alterations dictated by chromosome copy-number variations have been recently demonstrated in adult cancers, raising the question of whether multiple imprinted loci were also affected in WT. (sequentiabiotech.com)
  • Here especially highlighted variations of FISH are molecular combing, chromosome orientation-FISH (CO-FISH), telomere-FISH, parental origin determination FISH (POD-FISH), FISH to resolve the nuclear architecture, multicolor-FISH (mFISH) approaches, among other applied in chromoanagenesis studies, Comet-FISH, and CRISPR-mediated FISH-applications. (frontiersin.org)
  • However, the majority of cells with complex aberrations will be unstable and will not undergo cell division to give viable descendant cells. (radioprotection.org)
  • [1] [2] These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation . (wikipedia.org)
  • The cell harbors a complex aberration involving several chromosomes (red circle). (gsi.de)
  • Chromosome 9 copy number was determined on a cellular basis by FISH, and cellular DNA content was determined by Feulgen DNA staining and image cytometry. (johnshopkins.edu)
  • As a consequence of this flexibility, the scheme upon which the nomenclature is based differs substantially from other systems of aberration classification We call this system the Protocol for Aberration Identification and Nomenclature Terminology (PAINT). (utmb.edu)
  • The majority of cells with FISH aberrations were unstable. (bioone.org)
  • Conclusions: The lack of increase with grade in the percentage of positive specimens by FISH supports the hypothesis that chromosome 9 aberrations are critical events in bladder tumorigenesis for many patients. (johnshopkins.edu)
  • The main part deals with examples of modern FISH-applications, highlighting unique possibilities of the approach, like the possibility to study individual cells and even individual chromosomes. (frontiersin.org)
  • In the second half of the cell cycle the chromosomes clone themselves so that at mitosis, cell division, each cell has a full set of chromosomes. (whale.to)