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.
The alignment of CHROMOSOMES at homologous sequences.
Male germ cells derived from SPERMATOGONIA. The euploid primary spermatocytes undergo MEIOSIS and give rise to the haploid secondary spermatocytes which in turn give rise to SPERMATIDS.
Reproductive bodies produced by fungi.
The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.
The three-part structure of ribbon-like proteinaceous material that serves to align and join the paired homologous CHROMOSOMES. It is formed during the ZYGOTENE STAGE of the first meiotic division. It is a prerequisite for CROSSING OVER.
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 prophase of the first division of MEIOSIS (in which homologous CHROMOSOME SEGREGATION occurs). It is divided into five stages: leptonema, zygonema, PACHYNEMA, diplonema, and diakinesis.
The first phase of cell nucleus division, in which the CHROMOSOMES become visible, the CELL NUCLEUS starts to lose its identity, the SPINDLE APPARATUS appears, and the CENTRIOLES migrate toward opposite poles.
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.
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 process of germ cell development in the male from the primordial germ cells, through SPERMATOGONIA; SPERMATOCYTES; SPERMATIDS; to the mature haploid SPERMATOZOA.
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)
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 stage in the first meiotic prophase, following ZYGOTENE STAGE, when CROSSING OVER between homologous CHROMOSOMES begins.
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.
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)
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.
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.
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 process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).
Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell.
Proteins obtained from the species Schizosaccharomyces pombe. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.
A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.
The chromosomal constitution of cells, in which each type of CHROMOSOME is represented once. Symbol: N.
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.
The reproductive cells in multicellular organisms at various stages during GAMETOGENESIS.
Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.
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.
The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.
The phase of cell nucleus division following METAPHASE, in which the CHROMATIDS separate and migrate to opposite poles of the spindle.
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.
Cellular proteins encoded by the c-mos genes (GENES, MOS). They function in the cell cycle to maintain MATURATION PROMOTING FACTOR in the active state and have protein-serine/threonine kinase activity. Oncogenic transformation can take place when c-mos proteins are expressed at the wrong time.
Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle.
The process of germ cell development from the primordial GERM CELLS to the mature haploid GAMETES: ova in the female (OOGENESIS) or sperm in the male (SPERMATOGENESIS).
Proteins found in any species of fungus.
The process of germ cell development in plants, from the primordial PLANT GERM CELLS to the mature haploid PLANT GAMETES.
A cyclin subtype that is transported into the CELL NUCLEUS at the end of the G2 PHASE. It stimulates the G2/M phase transition by activating CDC2 PROTEIN KINASE.
Echinoderms having bodies of usually five radially disposed arms coalescing at the center.
Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.
Male germ cells derived from the haploid secondary SPERMATOCYTES. Without further division, spermatids undergo structural changes and give rise to SPERMATOZOA.
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 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)
A species of nematode that is widely used in biological, biochemical, and genetic studies.
The functional hereditary units of FUNGI.
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).
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.
A genus of black-spored basidiomycetous fungi of the family Coprinaceae, order Agaricales; some species are edible.
Interruptions in the sugar-phosphate backbone of DNA, across both strands adjacently.
Separase is a caspase-like cysteine protease, which plays a central role in triggering ANAPHASE by cleaving the SCC1/RAD21 subunit of the cohesin complex. Cohesin holds the sister CHROMATIDS together during METAPHASE and its cleavage results in chromosome segregation.
Proteins from the nematode species CAENORHABDITIS ELEGANS. The proteins from this species are the subject of scientific interest in the area of multicellular organism MORPHOGENESIS.
Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.
Protein kinase that drives both the mitotic and meiotic cycles in all eukaryotic organisms. In meiosis it induces immature oocytes to undergo meiotic maturation. In mitosis it has a role in the G2/M phase transition. Once activated by CYCLINS; MPF directly phosphorylates some of the proteins involved in nuclear envelope breakdown, chromosome condensation, spindle assembly, and the degradation of cyclins. The catalytic subunit of MPF is PROTEIN P34CDC2.
A mature haploid female germ cell extruded from the OVARY at OVULATION.
Euploid female germ cells of an early stage of OOGENESIS, derived from primordial germ cells during ovarian differentiation. Oogonia undergo MEIOSIS and give rise to haploid OOCYTES
The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.
The fertilizing element of plants that contains the male GAMETOPHYTES.
Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.
Deoxyribonucleic acid that makes up the genetic material of fungi.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Steroids with methyl groups at C-10 and C-13 and a branched 8-carbon chain at C-17. Members include compounds with any degree of unsaturation; however, CHOLESTADIENES is available for derivatives containing two double bonds.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in fungi.
Minute cells produced during development of an OOCYTE as it undergoes MEIOSIS. A polar body contains one of the nuclei derived from the first or second meiotic CELL DIVISION. Polar bodies have practically no CYTOPLASM. They are eventually discarded by the oocyte. (from King & Stansfield, A Dictionary of Genetics, 4th ed)
Euploid male germ cells of an early stage of SPERMATOGENESIS, derived from prespermatogonia. With the onset of puberty, spermatogonia at the basement membrane of the seminiferous tubule proliferate by mitotic then meiotic divisions and give rise to the haploid SPERMATOCYTES.
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.
The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.
An order of fungi in the phylum Ascomycota that multiply by budding. They include the telomorphic ascomycetous yeasts which are found in a very wide range of habitats.
A Rec A recombinase found in eukaryotes. Rad51 is involved in DNA REPAIR of double-strand breaks.
A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.
A unisexual reproduction without the fusion of a male and a female gamete (FERTILIZATION). In parthenogenesis, an individual is formed from an unfertilized OVUM that did not complete MEIOSIS. Parthenogenesis occurs in nature and can be artificially induced.
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.
A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
A cyclin A subtype primarily found in male GERM CELLS. It may play a role in the passage of SPERMATOCYTES into meiosis I.
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.
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.
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.
The male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans and in some other male-heterogametic species in which the homologue of the X chromosome has been retained.
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.
The final phase of cell nucleus division following ANAPHASE, in which two daughter nuclei are formed, the CYTOPLASM completes division, and the CHROMOSOMES lose their distinctness and are transformed into CHROMATIN threads.
Aurora kinase C is a chromosomal passenger protein that interacts with aurora kinase B in the regulation of MITOSIS. It is found primarily in GERM CELLS in the TESTIS, and may mediate CHROMOSOME SEGREGATION during SPERMATOGENESIS.
An E3 ubiquitin ligase primarily involved in regulation of the metaphase-to-anaphase transition during MITOSIS through ubiquitination of specific CELL CYCLE PROTEINS. Enzyme activity is tightly regulated through subunits and cofactors, which modulate activation, inhibition, and substrate specificity. The anaphase-promoting complex, or APC-C, is also involved in tissue differentiation in the PLACENTA, CRYSTALLINE LENS, and SKELETAL MUSCLE, and in regulation of postmitotic NEURONAL PLASTICITY and excitability.
Any method used for determining the location of and relative distances between genes on a chromosome.
Asexual reproduction resulting in the formation of viable seeds from FLOWERS without fertlization (i.e. use of POLLEN). Progeny plants produced from apomictic seeds are perfect clones of the parent.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
A cyclin B subtype that colocalizes with MICROTUBULES during INTERPHASE and is transported into the CELL NUCLEUS at the end of the G2 PHASE.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.
The phase of cell nucleus division following PROPHASE, when the breakdown of the NUCLEAR ENVELOPE occurs and the MITOTIC SPINDLE APPARATUS enters the nuclear region and attaches to the KINETOCHORES.
A family of highly conserved serine-threonine kinases that are involved in the regulation of MITOSIS. They are involved in many aspects of cell division, including centrosome duplication, SPINDLE APPARATUS formation, chromosome alignment, attachment to the spindle, checkpoint activation, and CYTOKINESIS.
The failure of PLANTS to complete fertilization and obtain seed (SEEDS) as a result of defective POLLEN or ovules, or other aberrations. (Dict. of Plant Genet. and Mol. Biol., 1998)
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.
Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.
Transforming proteins coded by mos oncogenes. The v-mos proteins were originally isolated from the Moloney murine sarcoma virus (Mo-MSV).
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.
Phosphoprotein with protein kinase activity that functions in the G2/M phase transition of the CELL CYCLE. It is the catalytic subunit of the MATURATION-PROMOTING FACTOR and complexes with both CYCLIN A and CYCLIN B in mammalian cells. The maximal activity of cyclin-dependent kinase 1 is achieved when it is fully dephosphorylated.
Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.
An exchange of DNA between matching or similar sequences.
Highly conserved proteins that specifically bind to and activate the anaphase-promoting complex-cyclosome, promoting ubiquitination and proteolysis of cell-cycle-regulatory proteins. Cdc20 is essential for anaphase-promoting complex activity, initiation of anaphase, and cyclin proteolysis during mitosis.

Meiosis: MeiRNA hits the spot. (1/6057)

The protein Mei2 performs at least two functions required in fission yeast for the switch from mitotic to meiotic cell cycles. One of these functions also requires meiRNA. It appears that meiRNA targets Mei2 to the nucleus, where it can promote the first meiotic division.  (+info)

SWM1, a developmentally regulated gene, is required for spore wall assembly in Saccharomyces cerevisiae. (2/6057)

Meiosis in Saccharomyces cerevisiae is followed by encapsulation of haploid nuclei within multilayered spore walls. Formation of this spore-specific wall requires the coordinated activity of enzymes involved in the biosynthesis of its components. Completion of late events in the sporulation program, leading to spore wall formation, requires the SWM1 gene. SWM1 is expressed at low levels during vegetative growth but its transcription is strongly induced under sporulating conditions, with kinetics similar to those of middle sporulation-specific genes. Homozygous swm1Delta diploids proceed normally through both meiotic divisions but fail to produce mature asci. Consistent with this finding, swm1Delta mutant asci display enhanced sensitivity to enzymatic digestion and heat shock. Deletion of SWM1 specifically affects the expression of mid-late and late sporulation-specific genes. All of the phenotypes observed are similar to those found for the deletion of SPS1 or SMK1, two putative components of a sporulation-specific MAP kinase cascade. However, epistasis analyses indicate that Swm1p does not form part of the Sps1p-Smk1p-MAP kinase pathway. We propose that Swm1p, a nuclear protein, would participate in a different signal transduction pathway that is also required for the coordination of the biochemical and morphological events occurring during the last phase of the sporulation program.  (+info)

Comparative sequence analysis of human minisatellites showing meiotic repeat instability. (3/6057)

The highly variable human minisatellites MS32 (D1S8), MS31A (D7S21), and CEB1 (D2S90) all show recombination-based repeat instability restricted to the germline. Mutation usually results in polar interallelic conversion or occasionally in crossovers, which, at MS32 at least, extend into DNA flanking the repeat array, defining a localized recombination hotspot and suggesting that cis-acting elements in flanking DNA can influence repeat instability. Therefore, comparative sequence analysis was performed to search for common flanking elements associated with these unstable loci. All three minisatellites are located in GC-rich DNA abundant in dispersed and tandem repetitive elements. There were no significant sequence similarities between different loci upstream of the unstable end of the repeat array. Only one of the three loci showed clear evidence for putative coding sequences near the minisatellite. No consistent patterns of thermal stability or DNA secondary structure were shared by DNA flanking these loci. This work extends previous data on the genomic environment of minisatellites. In addition, this work suggests that recombinational activity is not controlled by primary or secondary characteristics of the DNA sequence flanking the repeat array and is not obviously associated with gene promoters as seen in yeast.  (+info)

hMSH5: a human MutS homologue that forms a novel heterodimer with hMSH4 and is expressed during spermatogenesis. (4/6057)

MutS homologues have been identified in nearly all organisms examined to date. They play essential roles in maintaining mitotic genetic fidelity and meiotic segregation fidelity. MutS homologues appear to function as a molecular switch that signals genomic manipulation events. Here we describe the identification of the human homologue of the Saccharomyces cerevisiae MSH5, which is known to participate in meiotic segregation fidelity and crossing-over. The human MSH5 (hMSH5) was localized to chromosome 6p22-21 and appears to play a role in meiosis because expression is induced during spermatogenesis between the late primary spermatocytes and the elongated spermatid phase. hMSH5 interacts specifically with hMSH4, confirming the generality of functional heterodimeric interactions in the eukaryotic MutS homologue, which also includes hMSH2-hMSH3 and hMSH2-hMSH6.  (+info)

Sequential PKC- and Cdc2-mediated phosphorylation events elicit zebrafish nuclear envelope disassembly. (5/6057)

Molecular markers of the zebrafish inner nuclear membrane (NEP55) and nuclear lamina (L68) were identified, partially characterized and used to demonstrate that disassembly of the zebrafish nuclear envelope requires sequential phosphorylation events by first PKC, then Cdc2 kinase. NEP55 and L68 are immunologically and functionally related to human LAP2beta and lamin B, respectively. Exposure of zebrafish nuclei to meiotic cytosol elicits rapid phosphorylation of NEP55 and L68, and disassembly of both proteins. L68 phosphorylation is completely inhibited by simultaneous inhibition of Cdc2 and PKC and only partially blocked by inhibition of either kinase. NEP55 phosphorylation is completely prevented by inhibition or immunodepletion of cytosolic Cdc2. Inhibition of cAMP-dependent kinase, MEK or CaM kinase II does not affect NEP55 or L68 phosphorylation. In vitro, nuclear envelope disassembly requires phosphorylation of NEP55 and L68 by both mammalian PKC and Cdc2. Inhibition of either kinase is sufficient to abolish NE disassembly. Furthermore, novel two-step phosphorylation assays in cytosol and in vitro indicate that PKC-mediated phosphorylation of L68 prior to Cdc2-mediated phosphorylation of L68 and NEP55 is essential to elicit nuclear envelope breakdown. Phosphorylation elicited by Cdc2 prior to PKC prevents nuclear envelope disassembly even though NEP55 is phosphorylated. The results indicate that sequential phosphorylation events elicited by PKC, followed by Cdc2, are required for zebrafish nuclear disassembly. They also argue that phosphorylation of inner nuclear membrane integral proteins is not sufficient to promote nuclear envelope breakdown, and suggest a multiple-level regulation of disassembly of nuclear envelope components during meiosis and at mitosis.  (+info)

Characterization of a Caenorhabditis elegans recA-like gene Ce-rdh-1 involved in meiotic recombination. (6/6057)

A recA-like gene was identified in the Caenorhabditis elegans genome project database. The putative product of the gene, termed Ce-rdh-1 (C. elegans RAD51 and DMC1/LIM15 homolog 1), consists of 357 amino acid residues. The predicted amino acid sequence of Ce-rdh-1 showed 46-60% identity to both RAD51 type and DMC1/LIM15 type genes in several eukaryote species. The results of RNAi (RNA-mediated interference) indicated that repression of Ce-rdh-1 blocked chromosome condensation of six bivalents and dissociation of chiasmata in oocytes of F1 progeny. Oogenesis did not proceed to the diakinesis stage. Accordingly, all the eggs produced (F2) died in early stages. These results suggest that Ce-rdh-1 participates in meiotic recombination.  (+info)

Gene expression and chromatin organization during mouse oocyte growth. (7/6057)

Mouse oocytes can be classified according to their chromatin organization and the presence [surrounded nucleolus (SN) oocytes] or absence [nonsurrounded nucleolus (NSN) oocytes] of a ring of Hoechst-positive chromatin around the nucleolus. Following fertilization only SN oocytes are able to develop beyond the two-cell stage. These studies indicate a correlation between SN and NSN chromatin organization and the developmental competence of the female gamete, which may depend on gene expression. In the present study, we have used the HSP70.1Luc transgene (murine HSP70.1 promoter + reporter gene firefly luciferase) to analyze gene expression in oocytes isolated from ovaries of 2-day- to 13-week-old females. Luciferase was assayed on oocytes after classification as SN or NSN type. Our data show that SN oocytes always exhibit a higher level of luciferase activity, demonstrating a higher gene expression in this category. Only after meiotic resumption, metaphase II oocytes derived from NSN or SN oocytes acquire the same level of transgene expression. We suggest that the limited availability of transcripts and corresponding proteins, excluded from the cytoplasm until GVBD in NSN oocytes, could explain why these oocytes have a lower ability to sustain embryonic development beyond the two-cell stage at which major zygotic transcription occurs. With this study we have furthered our knowledge of epigenetic regulation of gene expression in oogenesis.  (+info)

Germ cell development in the XXY mouse: evidence that X chromosome reactivation is independent of sexual differentiation. (8/6057)

Prior to entry into meiosis, XX germ cells in the fetal ovary undergo X chromosome reactivation. The signal for reactivation is thought to emanate from the genital ridge, but it is unclear whether it is specific to the developing ovary. To determine whether the signals are present in the developing testis as well as the ovary, we examined the expression of X-linked genes in germ cells from XXY male mice. To facilitate this analysis, we generated XXY and XX fetuses carrying X chromosomes that were differentially marked and subject to nonrandom inactivation. This pattern of nonrandom inactivation was maintained in somatic cells but, in XX as well as XXY fetuses, both parental alleles were expressed in germ cell-enriched cell populations. Because testis differentiation is temporally and morphologically normal in the XXY testis and because all germ cells embark upon a male pathway of development, these results provide compelling evidence that X chromosome reactivation in fetal germ cells is independent of the somatic events of sexual differentiation. Proper X chromosome dosage is essential for the normal fertility of male mammals, and abnormalities in germ cell development are apparent in the XXY testis within several days of X reactivation. Studies of exceptional germ cells that survive in the postnatal XXY testis demonstrated that surviving germ cells are exclusively XY and result from rare nondisjunctional events that give rise to clones of XY cells.  (+info)

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.

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.

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.

Fungal spores are defined as the reproductive units of fungi that are produced by specialized structures called hyphae. These spores are typically single-celled and can exist in various shapes such as round, oval, or ellipsoidal. They are highly resistant to extreme environmental conditions like heat, cold, and dryness, which allows them to survive for long periods until they find a suitable environment to germinate and grow into a new fungal organism. Fungal spores can be found in the air, water, soil, and on various surfaces, making them easily dispersible and capable of causing infections in humans, animals, and plants.

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.

The synaptonemal complex is a protein structure that forms between two homologous chromosomes during meiosis, the type of cell division that leads to the production of gametes (sex cells). The synaptonemal complex consists of two lateral elements, which are associated with each of the homologous chromosomes, and a central element that runs parallel to the length of the complex and connects the two lateral elements.

The synaptonemal complex plays a crucial role in the process of genetic recombination, which occurs during meiosis. Genetic recombination is the exchange of genetic material between two homologous chromosomes that results in new combinations of genes on the chromosomes. This process helps to increase genetic diversity and is essential for the proper segregation of chromosomes during meiosis.

The synaptonemal complex also helps to ensure that the correct number of chromosomes are distributed to each gamete by holding the homologous chromosomes together until they can be properly aligned and separated during meiosis. Mutations in genes involved in the formation and maintenance of the synaptonemal complex can lead to fertility problems, developmental abnormalities, and other genetic disorders.

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.

Meiotic Prophase I is a stage in the meiotic division of cellular reproduction that results in the formation of gametes or sex cells (sperm and egg). It is the first of five stages in Meiosis I, which is a type of cell division that reduces the chromosome number by half.

During Meiotic Prophase I, homologous chromosomes pair and form tetrads (four-stranded structures), which then undergo genetic recombination or crossing over, resulting in new combinations of alleles on the chromatids of each homologous chromosome. This stage can be further divided into several substages: leptonema, zygonema, pachynema, diplonema, and diakinesis. These substages are characterized by distinct changes in chromosome structure and behavior, including the condensation and movement of the chromosomes, as well as the formation and dissolution of the synaptonemal complex, a protein structure that holds the homologous chromosomes together during crossing over.

Overall, Meiotic Prophase I is a critical stage in meiosis that ensures genetic diversity in offspring by shuffling the genetic material between homologous chromosomes and creating new combinations of alleles.

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.

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.

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.

Spermatogenesis is the process by which sperm cells, or spermatozoa, are produced in male organisms. It occurs in the seminiferous tubules of the testes and involves several stages:

1. Spermatocytogenesis: This is the initial stage where diploid spermatogonial stem cells divide mitotically to produce more spermatogonia, some of which will differentiate into primary spermatocytes.
2. Meiosis: The primary spermatocytes undergo meiotic division to form haploid secondary spermatocytes, which then divide again to form haploid spermatids. This process results in the reduction of chromosome number from 46 (diploid) to 23 (haploid).
3. Spermiogenesis: The spermatids differentiate into spermatozoa, undergoing morphological changes such as the formation of a head and tail. During this stage, most of the cytoplasm is discarded, resulting in highly compacted and streamlined sperm cells.
4. Spermation: The final stage where mature sperm are released from the seminiferous tubules into the epididymis for further maturation and storage.

The entire process takes approximately 72-74 days in humans, with continuous production throughout adulthood.

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.

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).

The pachytene stage is a phase in the meiotic division of sex cells (gametes) such as sperm and egg cells, specifically during prophase I. In this stage, homologous chromosomes are fully paired and have formed tetrads, or four-stranded structures called chiasma where genetic recombination occurs between the non-sister chromatids of each homologous chromosome. This is a crucial step in the creation of genetic diversity in the offspring. The pachytene stage is characterized by the presence of a protein matrix called the synaptonemal complex, which holds the homologous chromosomes together and facilitates crossing over.

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.

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.

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.

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.

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.

Oogenesis is the biological process of formation and maturation of female gametes, or ova or egg cells, in the ovary. It begins during fetal development and continues throughout a woman's reproductive years. The process involves the division and differentiation of a germ cell (oogonium) into an immature ovum (oocyte), which then undergoes meiotic division to form a mature ovum capable of being fertilized by sperm.

The main steps in oogenesis include:

1. Multiplication phase: The oogonia divide mitotically to increase their number.
2. Growth phase: One of the oogonia becomes primary oocyte and starts to grow, accumulating nutrients and organelles required for future development.
3. First meiotic division: The primary oocyte undergoes an incomplete first meiotic division, resulting in two haploid cells - a secondary oocyte and a smaller cell called the first polar body. This division is arrested in prophase I until puberty.
4. Second meiotic division: At ovulation or just before fertilization, the secondary oocyte completes the second meiotic division, producing another small cell, the second polar body, and a mature ovum (egg) with 23 chromosomes.
5. Fertilization: The mature ovum can be fertilized by a sperm, restoring the normal diploid number of chromosomes in the resulting zygote.

Oogenesis is a complex and highly regulated process that involves various hormonal signals and cellular interactions to ensure proper development and maturation of female gametes for successful 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.

I'm sorry for any confusion, but "Schizosaccharomyces pombe proteins" is not a medical term or concept. Schizosaccharomyces pombe is a type of single-celled microorganism called a yeast, which is often used as a model organism in scientific research. Proteins are complex molecules that do most of the work in cells and are necessary for the structure, function, and regulation of the body's tissues and organs.

In the context of scientific research, "Schizosaccharomyces pombe proteins" would refer to the specific proteins found in or studied using this particular type of yeast. These proteins may have similarities to human proteins and can be used to help understand basic biological processes, as well as diseases that occur in humans. However, it is important to note that while research using model organisms like Schizosaccharomyces pombe has led to many important discoveries, the findings may not always translate directly to humans.

I apologize for any confusion, but "Schizosaccharomyces" is not a medical term. It is a genus name in the field of microbiology and genetics, referring to a group of budding, tear-shaped yeasts that are widely used as model organisms in scientific research. The most well-known species within this genus is Schizosaccharomyces pombe, which has been extensively studied for its cell cycle regulation, DNA repair mechanisms, and other fundamental biological processes.

If you have any questions related to medical terminology or health-related topics, I would be happy to help.

"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.

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.

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.

Germ cells are the reproductive cells, also known as sex cells, that combine to form offspring in sexual reproduction. In females, germ cells are called ova or egg cells, and in males, they are called spermatozoa or sperm cells. These cells are unique because they carry half the genetic material necessary for creating new life. They are produced through a process called meiosis, which reduces their chromosome number by half, ensuring that when two germ cells combine during fertilization, the normal diploid number of chromosomes is restored.

Saccharomyces cerevisiae proteins are the proteins that are produced by the budding yeast, Saccharomyces cerevisiae. This organism is a single-celled eukaryote that has been widely used as a model organism in scientific research for many years due to its relatively simple genetic makeup and its similarity to higher eukaryotic cells.

The genome of Saccharomyces cerevisiae has been fully sequenced, and it is estimated to contain approximately 6,000 genes that encode proteins. These proteins play a wide variety of roles in the cell, including catalyzing metabolic reactions, regulating gene expression, maintaining the structure of the cell, and responding to environmental stimuli.

Many Saccharomyces cerevisiae proteins have human homologs and are involved in similar biological processes, making this organism a valuable tool for studying human disease. For example, many of the proteins involved in DNA replication, repair, and recombination in yeast have human counterparts that are associated with cancer and other diseases. By studying these proteins in yeast, researchers can gain insights into their function and regulation in humans, which may lead to new treatments for disease.

The testis, also known as the testicle, is a male reproductive organ that is part of the endocrine system. It is located in the scrotum, outside of the abdominal cavity. The main function of the testis is to produce sperm and testosterone, the primary male sex hormone.

The testis is composed of many tiny tubules called seminiferous tubules, where sperm are produced. These tubules are surrounded by a network of blood vessels, nerves, and supportive tissues. The sperm then travel through a series of ducts to the epididymis, where they mature and become capable of fertilization.

Testosterone is produced in the Leydig cells, which are located in the interstitial tissue between the seminiferous tubules. Testosterone plays a crucial role in the development and maintenance of male secondary sexual characteristics, such as facial hair, deep voice, and muscle mass. It also supports sperm production and sexual function.

Abnormalities in testicular function can lead to infertility, hormonal imbalances, and other health problems. Regular self-examinations and medical check-ups are recommended for early detection and treatment of any potential issues.

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.

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.

Anaphase is a stage in the cell division process called mitosis, where sister chromatids (the two copies of each chromosome formed during DNA replication) separate at the centromeres and move toward opposite poles of the cell. This separation is facilitated by the attachment of microtubules from the spindle apparatus to the kinetochores, protein structures located on the centromeres of each sister chromatid. Anaphase is followed by telophase, during which the nuclear membrane reforms around each set of separated chromosomes, and cytokinesis, the division of the cytoplasm to form two separate daughter cells.

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.

Proto-oncogene proteins c-mos are a type of serine/threonine protein kinase that play crucial roles in cell cycle regulation, particularly during the G2 phase and the transition to mitosis. The c-mos gene is a normal version of an oncogene, which can become cancer-causing when mutated or overexpressed. In its normal form, the c-mos protein is involved in controlling the progression of the cell cycle, meiosis, and also has been implicated in neuronal development and synaptic plasticity. Dysregulation of c-mos proto-oncogene proteins can contribute to tumorigenesis and cancer development.

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.

Gametogenesis is the biological process by which haploid gametes, or sex cells (sperm and egg cells), are produced through the meiotic division of diploid germ cells. In females, this process is called oogenesis, where an oogonium (diploid germ cell) undergoes mitosis to form an oocyte (immature egg cell). The oocyte then undergoes meiosis I to form a secondary oocyte and a polar body. After fertilization by a sperm cell, the secondary oocyte completes meiosis II to form a mature ovum or egg cell.

In males, this process is called spermatogenesis, where a spermatogonium (diploid germ cell) undergoes mitosis to form primary spermatocytes. Each primary spermatocyte then undergoes meiosis I to form two secondary spermatocytes, which subsequently undergo meiosis II to form four haploid spermatids. The spermatids then differentiate into spermatozoa or sperm cells through a process called spermiogenesis.

Gametogenesis is essential for sexual reproduction and genetic diversity, as it involves the random segregation of chromosomes during meiosis and the recombination of genetic material between homologous chromosomes.

Fungal proteins are a type of protein that is specifically produced and present in fungi, which are a group of eukaryotic organisms that include microorganisms such as yeasts and molds. These proteins play various roles in the growth, development, and survival of fungi. They can be involved in the structure and function of fungal cells, metabolism, pathogenesis, and other cellular processes. Some fungal proteins can also have important implications for human health, both in terms of their potential use as therapeutic targets and as allergens or toxins that can cause disease.

Fungal proteins can be classified into different categories based on their functions, such as enzymes, structural proteins, signaling proteins, and toxins. Enzymes are proteins that catalyze chemical reactions in fungal cells, while structural proteins provide support and protection for the cell. Signaling proteins are involved in communication between cells and regulation of various cellular processes, and toxins are proteins that can cause harm to other organisms, including humans.

Understanding the structure and function of fungal proteins is important for developing new treatments for fungal infections, as well as for understanding the basic biology of fungi. Research on fungal proteins has led to the development of several antifungal drugs that target specific fungal enzymes or other proteins, providing effective treatment options for a range of fungal diseases. Additionally, further study of fungal proteins may reveal new targets for drug development and help improve our ability to diagnose and treat fungal infections.

Gametogenesis in plants refers to the process of formation and development of gametes or sex cells (male: sperm and female: egg) through meiotic cell division. This process occurs within specialized reproductive organs called anthers (in male gametophyte) and ovules (in female gametophyte).

In the case of male gametogenesis, also known as microsporogenesis, diploid microspore mother cells undergo meiosis to produce haploid microspores. These microspores further develop into mature pollen grains through a process called pollen grain development or maturation.

Female gametogenesis, also known as megasporogenesis, involves the formation of megaspore mother cells within the ovule sac. The megaspore mother cell undergoes meiosis to produce four haploid megaspores. Only one of these megaspores survives and develops into a multicellular female gametophyte, also known as an embryo sac. This embryo sac contains several cells, including the egg cell, two synergids, three antipodal cells, and two polar nuclei.

These male and female gametes are involved in fertilization to form a zygote, which eventually develops into a new plant through the process of embryogenesis.

Cyclin B is a type of cyclin protein that regulates the cell cycle, specifically the transition from G2 phase to mitosis (M phase) in eukaryotic cells. Cyclin B binds and activates cyclin-dependent kinase 1 (CDK1), forming the complex known as M-phase promoting factor (MPF). This complex triggers the events leading to cell division, such as chromosome condensation, nuclear envelope breakdown, and spindle formation. The levels of cyclin B increase during the G2 phase and are degraded by the anaphase-promoting complex/cyclosome (APC/C) at the onset of anaphase, allowing the cell cycle to progress into the next phase.

I believe you may be mistakenly using the term "starfish" to refer to a medical condition. If so, the correct term is likely " asterixis," which is a medical sign characterized by rapid, rhythmic flapping or tremulous movements of the hands when they are extended and the wrist is dorsiflexed (held with the back of the hand facing upwards). This is often seen in people with certain neurological conditions such as liver failure or certain types of poisoning.

However, if you are indeed referring to the marine animal commonly known as a "starfish," there isn't a specific medical definition for it. Starfish, also known as sea stars, are marine animals belonging to the class Asteroidea in the phylum Echinodermata. They have a distinctive shape with five or more arms radiating from a central disc, and they move slowly along the ocean floor using their tube feet. Some species of starfish have the ability to regenerate lost body parts, including entire limbs or even their central disc.

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.

Spermatids are immature sperm cells that are produced during the process of spermatogenesis in the male testes. They are the product of the final stage of meiosis, where a diploid spermatocyte divides into four haploid spermatids. Each spermatid then undergoes a series of changes, including the development of a tail for motility and the condensation of its nucleus to form a head containing the genetic material. Once this process is complete, the spermatids are considered mature spermatozoa and are capable of fertilizing an egg.

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.

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.

'Caenorhabditis elegans' is a species of free-living, transparent nematode (roundworm) that is widely used as a model organism in scientific research, particularly in the fields of biology and genetics. It has a simple anatomy, short lifespan, and fully sequenced genome, making it an ideal subject for studying various biological processes and diseases.

Some notable features of C. elegans include:

* Small size: Adult hermaphrodites are about 1 mm in length.
* Short lifespan: The average lifespan of C. elegans is around 2-3 weeks, although some strains can live up to 4 weeks under laboratory conditions.
* Development: C. elegans has a well-characterized developmental process, with adults developing from eggs in just 3 days at 20°C.
* Transparency: The transparent body of C. elegans allows researchers to observe its internal structures and processes easily.
* Genetics: C. elegans has a fully sequenced genome, which contains approximately 20,000 genes. Many of these genes have human homologs, making it an excellent model for studying human diseases.
* Neurobiology: C. elegans has a simple nervous system, with only 302 neurons in the hermaphrodite and 383 in the male. This simplicity makes it an ideal organism for studying neural development, function, and behavior.

Research using C. elegans has contributed significantly to our understanding of various biological processes, including cell division, apoptosis, aging, learning, and memory. Additionally, studies on C. elegans have led to the discovery of many genes associated with human diseases such as cancer, neurodegenerative disorders, and metabolic conditions.

Fungal genes refer to the genetic material present in fungi, which are eukaryotic organisms that include microorganisms such as yeasts and molds, as well as larger organisms like mushrooms. The genetic material of fungi is composed of DNA, just like in other eukaryotes, and is organized into chromosomes located in the nucleus of the cell.

Fungal genes are segments of DNA that contain the information necessary to produce proteins and RNA molecules required for various cellular functions. These genes are transcribed into messenger RNA (mRNA) molecules, which are then translated into proteins by ribosomes in the cytoplasm.

Fungal genomes have been sequenced for many species, revealing a diverse range of genes that encode proteins involved in various cellular processes such as metabolism, signaling, and regulation. Comparative genomic analyses have also provided insights into the evolutionary relationships among different fungal lineages and have helped to identify unique genetic features that distinguish fungi from other eukaryotes.

Understanding fungal genes and their functions is essential for advancing our knowledge of fungal biology, as well as for developing new strategies to control fungal pathogens that can cause diseases in humans, animals, and plants.

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.

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.

"Coprinus" is a genus of fungi in the family Agaricaceae. It includes several species commonly known as "ink caps" or "shaggy manes." These mushrooms are characterized by their slimy, shaggy caps and the dark ink-like liquid that oozes from the gills when they mature. Some species of Coprinus are edible and considered delicacies, while others can cause adverse reactions if consumed with alcohol. It's important to note that proper identification is necessary before consuming any wild mushrooms.

Double-stranded DNA breaks (DSBs) refer to a type of damage that occurs in the DNA molecule when both strands of the double helix are severed or broken at the same location. This kind of damage is particularly harmful to cells because it can disrupt the integrity and continuity of the genetic material, potentially leading to genomic instability, mutations, and cell death if not properly repaired.

DSBs can arise from various sources, including exposure to ionizing radiation, chemical agents, free radicals, reactive oxygen species (ROS), and errors during DNA replication or repair processes. Unrepaired or incorrectly repaired DSBs have been implicated in numerous human diseases, such as cancer, neurodegenerative disorders, and premature aging.

Cells possess several mechanisms to repair double-stranded DNA breaks, including homologous recombination (HR) and non-homologous end joining (NHEJ). HR is a more accurate repair pathway that uses a homologous template, typically the sister chromatid, to restore the original DNA sequence. NHEJ, on the other hand, directly ligates the broken ends together, often resulting in small deletions or insertions at the break site and increased risk of errors. The choice between these two pathways depends on various factors, such as the cell cycle stage, the presence of nearby breaks, and the availability of repair proteins.

In summary, double-stranded DNA breaks are severe forms of DNA damage that can have detrimental consequences for cells if not properly repaired. Cells employ multiple mechanisms to address DSBs, with homologous recombination and non-homologous end joining being the primary repair pathways.

Separase is not a medical term itself, but it is a biological term used in the field of cell biology and genetics. Separase is an enzyme that plays a crucial role in the separation of chromosomes during cell division (mitosis and meiosis).

In more detail, separase is a protease enzyme that contributes to the breakdown of cohesin complexes, which are protein structures that hold sister chromatids together after DNA replication. Separase's function is essential for the proper separation of chromosomes during anaphase, the stage of mitosis where sister chromatids are pulled apart and moved to opposite poles of the cell.

While not a medical term per se, understanding separase and its role in cell division can help researchers better understand certain genetic disorders or diseases that may be caused by errors in cell division.

'Caenorhabditis elegans' (C. elegans) is a type of free-living, transparent nematode (roundworm) that is often used as a model organism in scientific research. C. elegans proteins refer to the various types of protein molecules that are produced by the organism's genes and play crucial roles in maintaining its biological functions.

Proteins are complex molecules made up of long chains of amino acids, and they are involved in virtually every cellular process, including metabolism, DNA replication, signal transduction, and transportation of molecules within the cell. In C. elegans, proteins are encoded by genes, which are transcribed into messenger RNA (mRNA) molecules that are then translated into protein sequences by ribosomes.

Studying C. elegans proteins is important for understanding the basic biology of this organism and can provide insights into more complex biological systems, including humans. Because C. elegans has a relatively simple nervous system and a short lifespan, it is often used to study neurobiology, aging, and development. Additionally, because many of the genes and proteins in C. elegans have counterparts in other organisms, including humans, studying them can provide insights into human disease processes and potential therapeutic targets.

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.

Maturation-Promoting Factor (MPF) is not a medical term per se, but it is commonly used in the field of cell biology and cancer research. MPF refers to a complex of two proteins that play a crucial role in regulating the cell cycle, specifically during the transition from the G2 phase to mitosis (M phase).

MPF is composed of a cyclin-dependent kinase (CDK1) and a regulatory subunit called cyclin B. During the late G2 phase, the levels of cyclin B increase, which leads to the activation of CDK1. Once activated, MPF triggers a series of events that promote mitosis, including chromosome condensation, nuclear envelope breakdown, and spindle formation.

In summary, Maturation-Promoting Factor (MPF) is a protein complex made up of CDK1 and cyclin B, which regulates the transition from the G2 phase to mitosis during the cell cycle.

An ovum is the female reproductive cell, or gamete, produced in the ovaries. It is also known as an egg cell and is released from the ovary during ovulation. When fertilized by a sperm, it becomes a zygote, which can develop into a fetus. The ovum contains half the genetic material necessary to create a new individual.

Oogonia are the diploid stem cells that are present in the ovary and give rise to oocytes (haploid cells) through the process of mitosis. These oocytes have the potential to develop into mature eggs or ova during female fetal development and after birth, which is a unique characteristic of human female reproduction. The oogonia are enclosed within primordial follicles that protect and nourish them as they develop into oocytes.

It's worth noting that in contrast to males, who continue to produce sperm throughout their reproductive lives, females are born with a finite number of oocytes already present in their ovaries, which is typically around 1-2 million at birth. Over time, this number decreases due to natural attrition and ovulation, leaving only about 400,000 oocytes by puberty, and declining further with age until menopause when the supply of oocytes is depleted.

Fertilization is the process by which a sperm cell (spermatozoon) penetrates and fuses with an egg cell (ovum), resulting in the formation of a zygote. This fusion of genetic material from both the male and female gametes initiates the development of a new organism. In human biology, fertilization typically occurs in the fallopian tube after sexual intercourse, when a single sperm out of millions is able to reach and penetrate the egg released from the ovary during ovulation. The successful fusion of these two gametes marks the beginning of pregnancy.

Pollen, in a medical context, refers to the fine powder-like substance produced by the male reproductive organ of seed plants. It contains microscopic grains known as pollen grains, which are transported by various means such as wind, water, or insects to the female reproductive organ of the same or another plant species for fertilization.

Pollen can cause allergic reactions in some individuals, particularly during the spring and summer months when plants release large amounts of pollen into the air. These allergies, also known as hay fever or seasonal allergic rhinitis, can result in symptoms such as sneezing, runny nose, congestion, itchy eyes, and coughing.

It is important to note that while all pollen has the potential to cause allergic reactions, certain types of plants, such as ragweed, grasses, and trees, are more likely to trigger symptoms in sensitive individuals.

Microtubules are hollow, cylindrical structures composed of tubulin proteins in the cytoskeleton of eukaryotic cells. They play crucial roles in various cellular processes such as maintaining cell shape, intracellular transport, and cell division (mitosis and meiosis). Microtubules are dynamic, undergoing continuous assembly and disassembly, which allows them to rapidly reorganize in response to cellular needs. They also form part of important cellular structures like centrioles, basal bodies, and cilia/flagella.

Fungal DNA refers to the genetic material present in fungi, which are a group of eukaryotic organisms that include microorganisms such as yeasts and molds, as well as larger organisms like mushrooms. The DNA of fungi, like that of all living organisms, is made up of nucleotides that are arranged in a double helix structure.

Fungal DNA contains the genetic information necessary for the growth, development, and reproduction of fungi. This includes the instructions for making proteins, which are essential for the structure and function of cells, as well as other important molecules such as enzymes and nucleic acids.

Studying fungal DNA can provide valuable insights into the biology and evolution of fungi, as well as their potential uses in medicine, agriculture, and industry. For example, researchers have used genetic engineering techniques to modify the DNA of fungi to produce drugs, biofuels, and other useful products. Additionally, understanding the genetic makeup of pathogenic fungi can help scientists develop new strategies for preventing and treating fungal infections.

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.

Cholestenes are a type of steroid that is characterized by having a double bond between the second and third carbon atoms in the steroid nucleus. They are precursors to cholesterol, which is an essential component of cell membranes and a precursor to various hormones and bile acids. Cholestenes can be found in some foods, but they are also synthesized in the body from other steroids.

Cholestenes are not typically referred to in medical terminology, as the term is more commonly used in biochemistry and organic chemistry. However, abnormal levels of cholestenes or related compounds may be detected in certain medical tests, such as those used to diagnose liver or gallbladder disorders.

Gene expression regulation in fungi refers to the complex cellular processes that control the production of proteins and other functional gene products in response to various internal and external stimuli. This regulation is crucial for normal growth, development, and adaptation of fungal cells to changing environmental conditions.

In fungi, gene expression is regulated at multiple levels, including transcriptional, post-transcriptional, translational, and post-translational modifications. Key regulatory mechanisms include:

1. Transcription factors (TFs): These proteins bind to specific DNA sequences in the promoter regions of target genes and either activate or repress their transcription. Fungi have a diverse array of TFs that respond to various signals, such as nutrient availability, stress, developmental cues, and quorum sensing.
2. Chromatin remodeling: The organization and compaction of DNA into chromatin can influence gene expression. Fungi utilize ATP-dependent chromatin remodeling complexes and histone modifying enzymes to alter chromatin structure, thereby facilitating or inhibiting the access of transcriptional machinery to genes.
3. Non-coding RNAs: Small non-coding RNAs (sncRNAs) play a role in post-transcriptional regulation of gene expression in fungi. These sncRNAs can guide RNA-induced transcriptional silencing (RITS) complexes to specific target loci, leading to the repression of gene expression through histone modifications and DNA methylation.
4. Alternative splicing: Fungi employ alternative splicing mechanisms to generate multiple mRNA isoforms from a single gene, thereby increasing proteome diversity. This process can be regulated by RNA-binding proteins that recognize specific sequence motifs in pre-mRNAs and promote or inhibit splicing events.
5. Protein stability and activity: Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and sumoylation, can influence their stability, localization, and activity. These PTMs play a crucial role in regulating various cellular processes, including signal transduction, stress response, and cell cycle progression.

Understanding the complex interplay between these regulatory mechanisms is essential for elucidating the molecular basis of fungal development, pathogenesis, and drug resistance. This knowledge can be harnessed to develop novel strategies for combating fungal infections and improving agricultural productivity.

Polar bodies are small, non-functional cells that are produced during the process of female meiosis, which results in the formation of an egg cell. They are formed when cytoplasmic divisions occur without subsequent cytokinesis, resulting in the separation of a small amount of cytoplasm and organelles from the main cell.

In the first meiotic division, a primary oocyte divides into a larger secondary oocyte and a smaller polar body, which contains half the number of chromosomes as the original cell. During the second meiotic division, the secondary oocyte divides into a larger ovum (egg) and another smaller polar body, again with half the number of chromosomes.

Polar bodies are typically extruded from the main cell and eventually disintegrate or are absorbed by surrounding cells. They do not contribute to the genetic makeup of the resulting egg or any offspring that may be produced from it. The formation of polar bodies helps ensure that the egg contains the correct number of chromosomes for normal development.

Spermatogonia are a type of diploid germ cells found in the seminiferous tubules of the testis. They are the stem cells responsible for sperm production (spermatogenesis) in males. There are two types of spermatogonia: A-dark (Ad) and A-pale (Ap). The Ad spermatogonia function as reserve stem cells, while the Ap spermatogonia serve as the progenitor cells that divide to produce type B spermatogonia. Type B spermatogonia then differentiate into primary spermatocytes, which undergo meiosis to form haploid spermatozoa.

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.

An ovary is a part of the female reproductive system in which ova or eggs are produced through the process of oogenesis. They are a pair of solid, almond-shaped structures located one on each side of the uterus within the pelvic cavity. Each ovary measures about 3 to 5 centimeters in length and weighs around 14 grams.

The ovaries have two main functions: endocrine (hormonal) function and reproductive function. They produce and release eggs (ovulation) responsible for potential fertilization and development of an embryo/fetus during pregnancy. Additionally, they are essential in the production of female sex hormones, primarily estrogen and progesterone, which regulate menstrual cycles, sexual development, and reproduction.

During each menstrual cycle, a mature egg is released from one of the ovaries into the fallopian tube, where it may be fertilized by sperm. If not fertilized, the egg, along with the uterine lining, will be shed, leading to menstruation.

Saccharomycetales is an order of fungi that are commonly known as "true yeasts." They are characterized by their single-celled growth and ability to reproduce through budding or fission. These organisms are widely distributed in nature and can be found in a variety of environments, including soil, water, and on the surfaces of plants and animals.

Many species of Saccharomycetales are used in industrial processes, such as the production of bread, beer, and wine. They are also used in biotechnology to produce various enzymes, vaccines, and other products. Some species of Saccharomycetales can cause diseases in humans and animals, particularly in individuals with weakened immune systems. These infections, known as candidiasis or thrush, can affect various parts of the body, including the skin, mouth, and genital area.

Rad51 recombinase is a protein involved in the repair of double-stranded DNA breaks through homologous recombination, a process that helps maintain genomic stability. This protein forms a nucleoprotein filament on single-stranded DNA, facilitating the search for and invasion of homologous sequences in double-stranded DNA. Rad51 recombinase is highly conserved across various species, including humans, and plays a crucial role in preventing genetic disorders, cancer, and aging caused by DNA damage.

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.

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.

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.

Parthenogenesis is a form of asexual reproduction in which offspring develop from unfertilized eggs or ovums. It occurs naturally in some plant and insect species, as well as a few vertebrates such as reptiles and fish. Parthenogenesis does not involve the fusion of sperm and egg cells; instead, the development of offspring is initiated by some other trigger, such as a chemical or physical stimulus. This type of reproduction results in offspring that are genetically identical to the parent organism. In humans and other mammals, parthenogenesis is not a natural occurrence and would require scientific intervention to induce.

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.

Endodeoxyribonucleases are a type of enzyme that cleave, or cut, phosphodiester bonds within the backbone of DNA molecules. These enzymes are also known as restriction endonucleases or simply restriction enzymes. They are called "restriction" enzymes because they were first discovered in bacteria, where they function to protect the organism from foreign DNA by cleaving and destroying invading viral DNA.

Endodeoxyribonucleases recognize specific sequences of nucleotides within the DNA molecule, known as recognition sites or restriction sites, and cut the phosphodiester bonds at specific locations within these sites. The cuts made by endodeoxyribonucleases can be either "sticky" or "blunt," depending on whether the enzyme leaves single-stranded overhangs or creates blunt ends at the site of cleavage, respectively.

Endodeoxyribonucleases are widely used in molecular biology research for various applications, including DNA cloning, genome mapping, and genetic engineering. They allow researchers to cut DNA molecules at specific sites, creating defined fragments that can be manipulated and recombined in a variety of ways.

Cyclin A1 is a type of cyclin protein that regulates the cell cycle, particularly during the S and G2 phases. It forms a complex with and acts as a regulatory subunit of cyclin-dependent kinase 2 (CDK2), helping to control the transition from the G1 phase to the S phase and from the S phase to the G2 phase. Cyclin A1 is expressed in various tissues, including ovary, testis, bone marrow, and lymphoid cells. Overexpression or dysregulation of cyclin A1 has been implicated in several types of cancer, making it a potential target for cancer therapy.

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.

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.

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.

The Y chromosome is one of the two sex-determining chromosomes in humans and many other animals, along with the X chromosome. The Y chromosome contains the genetic information that helps to determine an individual's sex as male. It is significantly smaller than the X chromosome and contains fewer genes.

The Y chromosome is present in males, who inherit it from their father. Females, on the other hand, have two X chromosomes, one inherited from each parent. The Y chromosome includes a gene called SRY (sex-determining region Y), which initiates the development of male sexual characteristics during embryonic development.

It is worth noting that the Y chromosome has a relatively high rate of genetic mutation and degeneration compared to other chromosomes, leading to concerns about its long-term viability in human evolution. However, current evidence suggests that the Y chromosome has been stable for at least the past 25 million years.

"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.

Telophase is a phase in the cell division process (mitosis or meiosis) where the chromosomes reach their most condensed form and move to the poles of the cell. The nuclear membrane begins to reform around each set of chromosomes, and the spindle fibers that were used to separate the chromosomes break down. This phase is followed by cytokinesis, where the cytoplasm of the cell divides, resulting in two separate daughter cells. In telophase I of meiosis, crossing over between homologous chromosomes has already occurred during prophase I and sister chromatids remain together until anaphase II.

Aurora Kinase C is a type of serine/threonine protein kinase that is involved in the regulation of cell division and mitosis. It plays a crucial role in the proper separation of chromosomes during cell division, ensuring the genetic stability of cells. Mutations in the gene that encodes Aurora Kinase C have been associated with various types of cancer, including colon, breast, and ovarian cancers. Inhibitors of Aurora Kinase C are being studied as potential cancer therapeutics.

The Anaphase-Promoting Complex/Cyclosome (APC/C) is a large E3 ubiquitin ligase complex that plays a crucial role in the regulation of the cell cycle. It is responsible for targeting specific proteins for degradation by the proteasome, which is a multi-subunit protein complex that mediates the controlled breakdown of ubiquitinated proteins.

During anaphase, the final stage of mitosis, the APC/C becomes active and triggers the degradation of several key regulatory proteins, including securin and cyclin B. The destruction of these proteins allows for the separation of chromosomes and the completion of cell division.

The APC/C is composed of multiple subunits, including a catalytic core that binds to ubiquitin-conjugating enzymes (E2s) and several coactivators that regulate its activity. The activation of the APC/C requires the binding of one of two coactivators, Cdc20 or CDH1, which recognize specific substrates for degradation.

Dysregulation of the APC/C has been implicated in various human diseases, including cancer and neurodegenerative disorders. Therefore, understanding the mechanisms that regulate its activity is an important area of research with potential therapeutic implications.

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.

Apomixis is a form of asexual reproduction in plants that involves the development of a seed without fertilization. It occurs through various mechanisms, such as agamospermy or parthenogenesis, where the embryo develops from an unfertilized egg cell or other cells within the ovule. This process bypasses the formation of gametes and meiosis, resulting in offspring that are genetically identical to the parent plant.

In agamospermy, the embryo sac develops without fertilization, and the chromosome number is maintained through mitotic divisions. In parthenogenesis, the egg cell develops into an embryo without being fertilized by a sperm cell. Apomixis can be advantageous for plant breeding as it allows for the rapid propagation of desirable traits and hybrids without the need for time-consuming and expensive traditional breeding methods. However, apomictic plants may also exhibit reduced genetic diversity, which can make them more susceptible to diseases and pests.

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.

Cyclin B1 is a type of cyclin protein that regulates the cell cycle, specifically the transition from G2 phase to mitosis (M phase) in eukaryotic cells. It forms a complex with and acts as a regulatory subunit of cyclin-dependent kinase 1 (CDK1), also known as CDC2. During the G2 phase, Cyclin B1 levels accumulate and upon reaching a certain threshold, it binds to CDK1 to form the maturation promoting factor (MPF). The activation of MPF triggers the onset of mitosis by promoting nuclear envelope breakdown, chromosome condensation, and other events required for cell division. After the completion of mitosis, Cyclin B1 is degraded by the ubiquitin-proteasome system, allowing the cell cycle to progress back into G1 phase.

Developmental gene expression regulation refers to the processes that control the activation or repression of specific genes during embryonic and fetal development. These regulatory mechanisms ensure that genes are expressed at the right time, in the right cells, and at appropriate levels to guide proper growth, differentiation, and morphogenesis of an organism.

Developmental gene expression regulation is a complex and dynamic process involving various molecular players, such as transcription factors, chromatin modifiers, non-coding RNAs, and signaling molecules. These regulators can interact with cis-regulatory elements, like enhancers and promoters, to fine-tune the spatiotemporal patterns of gene expression during development.

Dysregulation of developmental gene expression can lead to various congenital disorders and developmental abnormalities. Therefore, understanding the principles and mechanisms governing developmental gene expression regulation is crucial for uncovering the etiology of developmental diseases and devising potential therapeutic strategies.

Prometaphase is a stage in the cell division process called mitosis, where the nuclear membrane has broken down and the chromosomes are now moved into the center of the cell, also known as the metaphase plate. This movement is facilitated by the mitotic spindle, which attaches to specialized structures on the chromosomes called kinetochores. The prometaphase stage follows prophase and precedes metaphase in the mitosis process. It's characterized by the beginning of chromosome separation and the reorganization of the cell for the upcoming division into two daughter cells.

Aurora kinases are a family of serine/threonine protein kinases that play crucial roles in the regulation of cell division. There are three members of the Aurora kinase family, designated as Aurora A, Aurora B, and Aurora C. These kinases are involved in the proper separation of chromosomes during mitosis and meiosis, and their dysregulation has been implicated in various types of cancer.

Aurora A is primarily located at the centrosomes and spindle poles during cell division, where it regulates centrosome maturation, bipolar spindle formation, and chromosome segregation. Aurora B, on the other hand, is a component of the chromosomal passenger complex (CPC) that localizes to the centromeres during prophase and moves to the spindle midzone during anaphase. It plays essential roles in kinetochore-microtubule attachment, chromosome alignment, and cytokinesis. Aurora C is most similar to Aurora B and appears to have overlapping functions with it, although its specific roles are less well understood.

Dysregulation of Aurora kinases has been associated with various types of cancer, including breast, ovarian, colon, and lung cancers. Overexpression or amplification of Aurora A is observed in many cancers, leading to chromosomal instability and aneuploidy. Inhibition of Aurora kinases has emerged as a potential therapeutic strategy for cancer treatment, with several small molecule inhibitors currently under investigation in clinical trials.

'Plant infertility' is not a standard medical term, as it is typically used in the context of agriculture and plant biology. However, I can provide you with a general definition related to this context:

Plant infertility refers to the inability of a plant to produce viable seeds, fruits, or propagules due to various factors affecting its reproductive system. These factors may include genetic disorders, environmental stressors (such as extreme temperatures, drought, or nutrient deficiencies), pathogens, pests, or poor pollination. In some cases, assisted reproduction techniques, such as hand-pollination or embryo rescue, might be employed to overcome infertility issues in plants.

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.

'Drosophila proteins' refer to the proteins that are expressed in the fruit fly, Drosophila melanogaster. This organism is a widely used model system in genetics, developmental biology, and molecular biology research. The study of Drosophila proteins has contributed significantly to our understanding of various biological processes, including gene regulation, cell signaling, development, and aging.

Some examples of well-studied Drosophila proteins include:

1. HSP70 (Heat Shock Protein 70): A chaperone protein involved in protein folding and protection from stress conditions.
2. TUBULIN: A structural protein that forms microtubules, important for cell division and intracellular transport.
3. ACTIN: A cytoskeletal protein involved in muscle contraction, cell motility, and maintenance of cell shape.
4. BETA-GALACTOSIDASE (LACZ): A reporter protein often used to monitor gene expression patterns in transgenic flies.
5. ENDOGLIN: A protein involved in the development of blood vessels during embryogenesis.
6. P53: A tumor suppressor protein that plays a crucial role in preventing cancer by regulating cell growth and division.
7. JUN-KINASE (JNK): A signaling protein involved in stress response, apoptosis, and developmental processes.
8. DECAPENTAPLEGIC (DPP): A member of the TGF-β (Transforming Growth Factor Beta) superfamily, playing essential roles in embryonic development and tissue homeostasis.

These proteins are often studied using various techniques such as biochemistry, genetics, molecular biology, and structural biology to understand their functions, interactions, and regulation within the cell.

The v-mos oncogene protein is derived from the retrovirus called Moloney murine sarcoma virus (Mo-MSV). This oncogene encodes for a serine/threonine protein kinase, which is involved in cell proliferation and differentiation. When incorporated into the host genome during viral infection, the v-mos oncogene can cause unregulated cell growth and tumor formation, leading to sarcomas in mice. The normal cellular homolog of v-mos is called c-mos, which plays a crucial role in regulating cell division and is tightly controlled in normal cells. However, mutations or aberrant activation of c-mos can also contribute to oncogenic transformation and tumorigenesis.

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.

CDC2 protein kinase, also known as cell division cycle 2 or CDK1, is a type of enzyme that plays a crucial role in the regulation of the cell cycle. The cell cycle is the series of events that cells undergo as they grow, replicate their DNA, and divide into two daughter cells.

CDC2 protein kinase is a member of the cyclin-dependent kinase (CDK) family, which are serine/threonine protein kinases that are activated by binding to regulatory subunits called cyclins. CDC2 protein kinase is primarily associated with the regulation of the G2 phase and the entry into mitosis, the stage of the cell cycle where nuclear and cytoplasmic division occur.

CDC2 protein kinase functions by phosphorylating various target proteins, which alters their activity and contributes to the coordination of the different events that occur during the cell cycle. The activity of CDC2 protein kinase is tightly regulated through a variety of mechanisms, including phosphorylation and dephosphorylation, as well as the binding and destruction of cyclin subunits.

Dysregulation of CDC2 protein kinase has been implicated in various human diseases, including cancer, where uncontrolled cell division can lead to the formation of tumors. Therefore, understanding the regulation and function of CDC2 protein kinase is an important area of research in molecular biology and medicine.

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.

Homologous recombination is a type of genetic recombination that occurs between two similar or identical (homologous) segments of DNA. It is a natural process that helps to maintain the stability of an organism's genome and plays a crucial role in DNA repair, particularly the repair of double-strand breaks.

In homologous recombination, the two DNA molecules exchange genetic information through a series of steps, including the formation of Holliday junctions, where the strands cross over and exchange partners. This process can result in new combinations of genetic material, which can increase genetic diversity and contribute to evolution.

Homologous recombination is also used in biotechnology and genetic engineering to introduce specific changes into DNA sequences or to create genetically modified organisms.

CDC20 proteins are a type of regulatory protein that play a crucial role in the cell cycle, which is the process by which cells grow and divide. Specifically, CDC20 proteins are involved in the transition from metaphase to anaphase during mitosis, the phase of the cell cycle where chromosomes are separated and distributed to two daughter cells.

CDC20 proteins function as part of a larger complex called the anaphase-promoting complex/cyclosome (APC/C), which targets specific proteins for degradation by the proteasome. During metaphase, CDC20 binds to the APC/C and helps to activate it, leading to the degradation of securin and cyclin B, two proteins that are essential for maintaining the proper attachment of chromosomes to the spindle apparatus.

Once these proteins are degraded, the sister chromatids can be separated and moved to opposite poles of the cell, allowing for the completion of mitosis and the formation of two genetically identical daughter cells. In addition to their role in mitosis, CDC20 proteins have also been implicated in other cellular processes, including meiosis, DNA damage repair, and apoptosis.

... is divided into meiosis I and meiosis II which are further divided into Karyokinesis I, Cytokinesis I, Karyokinesis II ... Therefore, meiosis includes the stages of meiosis I (prophase I, metaphase I, anaphase I, telophase I) and meiosis II (prophase ... The two meiotic divisions are known as meiosis I and meiosis II. Before meiosis begins, during S phase of the cell cycle, the ... In some species, cells enter a resting phase known as interkinesis between meiosis I and meiosis II. Meiosis I and II are each ...
... refers to meiosis without chiasmata, which are structures that are necessary for recombination to occur and ... There is no crossing over during their meiosis, indicating that they have achiasmate meiosis. It is theorized that this failure ... It is thought that achiasmatic meiosis is polyphyletic, as there is no distinct pattern to its occurrence, nor to the methods ... Chiasmata play a crucial role in correctly segregating the chromosomes during meiosis I to maintain correct ploidy; when ...
... is a moth in the family Gelechiidae. Park and Ponomarenko described it in 1996. It is found in Thailand. The ...
The tetrad is the four spores produced after meiosis of a yeast or other Ascomycota, Chlamydomonas or other alga, or a plant. ... Under appropriate environmental conditions, diploids sporulate and undergo meiosis. The meiotic products, spores, remain ...
... occurs as a part of oocyte meiosis after meiotic arrest has occurred. In females, meiosis of an oocyte ... Meiosis is then arrested again during metaphase 2 until fertilisation. At fertilisation meiosis then resumes which results in ... Resumption of meiosis will resume following an ovulatory surge (ovulation) of luteinising hormone (LH). Meiosis was initially ... Primordial germ-cells (PGC'S) undergo meiosis leading to the formation of primordial follicles. At birth, meiosis arrests at ...
Meiosis is the opposite of auxesis, and is often compared to litotes. The term is derived from the Greek μειόω ("to make ... In rhetoric, meiosis is a euphemistic figure of speech that intentionally understates something or implies that it is lesser in ... Burton, Gideon O. "Meiosis". Silva Rhetoricae. Archived from the original on 2006-12-29. Retrieved 2006-12-24. v t e (Articles ... "Intolerable meiosis!" comments a character in William Golding's Fire Down Below as their ship encounters an iceberg after ...
... the function of meiosis. There are two conflicting theories on how meiosis arose. One is that meiosis evolved from prokaryotic ... Meiosis is distinct from mitosis in that a central feature of meiosis is the alignment of homologous chromosomes followed by ... If meiosis arose from prokaryotic transformation, during the early evolution of eukaryotes, mitosis and meiosis could have ... What is it specifically about stress that needs to be overcome by meiosis? And what is the specific benefit provided by meiosis ...
Bernstein, H.; Bernstein, C. (2013). Evolutionary Origin and Adaptive Function of Meiosis. Meiosis. InTech. ISBN 978-953-51- ...
"Meiosis". Retrieved 15 February 2007. Stapley, J.; Feulner, P. G.; Johnston, S. E.; Santure, A. W.; Smadja, C. M. (2017). " ... They segregate (separate) during meiosis such that each gamete contains only one of the alleles. When the gametes unite in the ... Molecular proof of segregation of genes was subsequently found through observation of meiosis by two scientists independently, ... Paternal and maternal chromosomes get separated in meiosis because during spermatogenesis the chromosomes are segregated on the ...
In contrast to mitosis, meiosis results in four haploid daughter cells by undergoing one round of DNA replication followed by ... Homologous chromosomes are separated in the first division (meiosis I), and sister chromatids are separated in the second ... mitosis and meiosis. Mitosis is part of the cell cycle, in which replicated chromosomes are separated into two new nuclei. Cell ... "Meiosis". Biological Science (6th ed.). Hoboken, New Jersey: Pearson. pp. 271-289. ISBN 978-0321976499. Casiraghi, A.; Suigo, L ...
"Audus, Leslie John (1911-2011)". Meiosis. Archived from the original on 29 September 2013. Retrieved 21 May 2013. "Audus, ...
Meiosis.) Artificial competence can be induced in laboratory procedures that involve making the cell passively permeable to DNA ...
The process of meiosis I is generally longer than meiosis II because it takes more time for the chromatin to replicate and for ... Proper homologous chromosome separation in meiosis I is crucial for sister chromatid separation in meiosis II. A failure to ... resulting from meiosis I undergo another cell division in meiosis II but without another round of chromosomal replication. The ... Meiosis is a round of two cell divisions that results in four haploid daughter cells that each contain half the number of ...
Moens, Peter (1987). Meiosis. Orlando: Academic Press. pp. 83-84. ISBN 978-0-323-15191-7. "Rapport d'activités Pro Natura" [Pro ... Narbel's research focused on cytogenetics, and her study of the process of meiosis in parthenogenic animals was described as ...
Chandley, A. (1 March 1988). "Meiosis in man". Trends in Genetics. 4 (3): 79-84. doi:10.1016/0168-9525(88)90045-5. ISSN 0168- ... Chandley also worked with Holt Radium Institute, and focussed on mutations and meiosis cell division, using cytogenetic ...
ISBN 0-521-56047-0. Lu BC, Raju NB (1970). "Meiosis in Coprinus. II. Chromosome pairing and the lampbrush diplotene stage of ... Like other coprinoid species, C. micaceus undergoes synchronous meiosis. The chromosomes are readily discernible with light ... and it has been used frequently as a model organism to study cell division and meiosis in basidiomycetes. Chemical analysis of ...
A meiosis II error can result in heterodisomy UPD if the gene loci crossed over in a similar fashion. Most occurrences of UPD ... A meiosis I error can result in isodisomic UPD if the gene loci in question crossed over, for example, a distal isodisomy would ... Heterodisomy (heterozygous) indicates a meiosis I error if the gene loci in question didn't cross over. When the child receives ... "Meiosis: Uniparental Disomy". Retrieved 29 February 2016. Angelman Syndrome, Online Mendelian Inheritance in Man "OMIM Entry ...
"Britten, James (1846 - 1924) , meiosis.org.uk". www.meiosis.org.uk. Archived from the original on 28 July 2017. Retrieved 28 ...
Meiosis I fails to complete, meiosis II creates two cells, one of which degenerates; three mitotic divisions form the ... Ixeris type: Meiosis I fails to complete; three rounds of nuclear division occur without cell-wall formation; wall formation ... The chromosomes double (endomitosis) and then meiosis proceeds in an unusual way, with the chromosome copies pairing up (rather ... Apomeiosis: "Without meiosis"; usually meaning the production of a meiotically unreduced gametophyte. Parthenogenesis: ...
Eslava AP, Alvarez MI, Delbrück M (October 1975). "Meiosis in Phycomyces". Proc. Natl. Acad. Sci. U.S.A. 72 (10): 4076-80. ... fuse to form a diploid cell which then undergoes meiosis to form haploid meiotic products. These then reproduce by mitotic ...
ISBN 978-0-19-954089-1. "Hillhouse, William Professor (1850 - 1910)". meiosis.org.uk. Archived from the original on 4 December ...
"Have You Tried Meiosis?". Western Advertising. 11 (6): 60-61. January 1928. "The Literature of Advertising in 1927". Western ...
1978). "Meiosis in Coprinus. VIII. A time-course study of the fusion and division of the spindle pole body during meiosis". ...
... circumvent this problem by segregating sister chromatids during meiosis I, leading to the term inverted meiosis, in which the ... Viera A, Page J, Rufas JS (2009). "Inverted meiosis: the true bugs as a model to study". Genome Dynamics. Karger. 5: 137-156. ... In the late 19th century, van Beneden (1883) and Boveri (1890) described meiosis for the first time through a careful ... In the holocentric chromosomes of C. elegans female meiosis, this problem is circumvented by restricting crossing over to form ...
Cohen is interested in mammalian meiosis, gametogenesis and the role of a variety of DNA repair pathways in mediating meiosis. ... "2022 Meiosis Conference GRC". www.grc.org. Retrieved 2022-02-09. "Eight receive Provost's Award for Distinguished Scholarship ... Her research considers DNA repair mechanisms and the regulation of crossing over during mammalian meiosis. She was awarded the ... 1 May 2000). "MutS homolog 4 localization to meiotic chromosomes is required for chromosome pairing during meiosis in male and ...
... I in meiosis is the most complex iteration of prophase that occurs in both plant cells and animal cells. To ensure ... Many species arrest meiosis in diplotene of prophase I until ovulation.: 98 In humans, decades can pass as oocytes remain ... Meiosis involves two rounds of chromosome segregation and thus undergoes prophase twice, resulting in prophase I and prophase ... Microscopy can be used to visualize condensed chromosomes as they move through meiosis and mitosis. Various DNA stains are used ...
Another mechanism involves meiosis. The majority of C. neoformans are mating "type a". Filaments of mating "type a" ordinarily ... Sexual reproduction with meiosis has been directly observed in all fungal phyla except Glomeromycota (genetic analysis suggests ... Karyogamy in the asci is followed immediately by meiosis and the production of ascospores. After dispersal, the ascospores may ... Because the products of meiosis are retained within the sac-like ascus, ascomycetes have been used for elucidating principles ...
Also see article Meiosis). Homologous recombinational repair employing BRCA1 is especially promoted during meiosis. It was ... Primordial follicles contain oocytes that are at an intermediate (prophase I) stage of meiosis. Meiosis is the general process ... during meiosis). The BRCA2 protein, which has a function similar to that of BRCA1, also interacts with the RAD51 protein. By ...
The oocyte is arrested in Meiosis II at the stage of metaphase II and is considered a secondary oocyte. Before ovulation, the ... See anatomy of sperm Nondisjunction-a failure of proper homolog separation in meiosis I, or sister chromatid separation in ... Mira A (September 1998). "Why is meiosis arrested?". Journal of Theoretical Biology. 194 (2): 275-87. Bibcode:1998JThBi.194.. ... and these oocytes are arrested at the prophase I stage of meiosis. In humans, as an example, oocytes are formed between three ...
Plants use meiosis to produce spores that develop into multicellular haploid gametophytes which produce gametes by mitosis. The ... "Mitosis, Meiosis, and Inheritance , Learn Science at Scitable". www.nature.com. Retrieved 1 March 2021. Jay Phelan (30 April ... This process involves meiosis (including meiotic recombination) occurring in the diploid primary oocyte to produce the haploid ... Gametes carry half the genetic information of an individual, one ploidy of each type, and are created through meiosis, in which ...
Meiosis is divided into meiosis I and meiosis II which are further divided into Karyokinesis I, Cytokinesis I, Karyokinesis II ... Therefore, meiosis includes the stages of meiosis I (prophase I, metaphase I, anaphase I, telophase I) and meiosis II (prophase ... The two meiotic divisions are known as meiosis I and meiosis II. Before meiosis begins, during S phase of the cell cycle, the ... In some species, cells enter a resting phase known as interkinesis between meiosis I and meiosis II. Meiosis I and II are each ...
Meiosis Maven. Fueled by her love of visual data and addicted to chromosomes, Abby Dernburg continues to study how homologous ... "This work is really exciting because many people think that some unusual features of C. elegans meiosis are just a weird worm ... I may wind up doing something not related to meiosis in the future, but I still think chromosomes are really intriguing. There ... Beyond C. elegans. Dernburgs laboratory recently branched out beyond the nematode C. elegans to study meiosis in planarians, ...
Steve McVickers, CEO of Meiosis highlighted the evolving role of variety promoters and optimism for the future "Meiosis ... NIAB EMR and Meiosis announce new collaborative working relationship 27 May 2020 ... Meiosis is part of the Nuclear Stock Association Group. designing and instigating development programmes that will maximise ... This agreement is part of Meiosis repositioning itself as a leading variety manager and plant material provider in developing ...
Answer: primary spermatocytes forming secondary spermatocytes. View course reproductive system for similar questions at Memory.com.
1998) Changes in carbohydrate metabolism of testicular germ cells during meiosis in the rat European Journal of Endocrinology ... Mitofusins are required for meiosis.. (A) Testes weight measurements from juvenile P24 mice. N ≥ 3. (B) Periodic Acid-Schiff ( ... As spermatocytes initiate meiosis, they cross the blood-testis-barrier (BTB) and become dependent on lactate secreted by ... Mitofusins are required for a metabolic shift during meiosis. Given the MPI abnormality in fusion-deficient mice, we wondered ...
Septin 7 is required for orderly meiosis in mouse oocytes. / Li, Sen; Ou, Xiang Hong; Wei, Liang et al. In: Cell Cycle, Vol. 11 ... Septin 7 is required for orderly meiosis in mouse oocytes. Sen Li, Xiang Hong Ou, Liang Wei, Zhen Bo Wang, Qing Hua Zhang, Ying ... keywords = "Meiosis, Mouse, Oocyte, Overexpression, Septin 7",. author = "Sen Li and Ou, {Xiang Hong} and Liang Wei and Wang, { ... Septin 7 is required for orderly meiosis in mouse oocytes. Cell Cycle. 2012 Sept 1;11(17):3211-3218. doi: 10.4161/cc.21553 ...
Early developmental, meiosis-specific proteins-Spo11, Msh4-1, and Msh5-Affect subsequent genome reorganization in Paramecium ... Early developmental, meiosis-specific proteins-Spo11, Msh4-1, and Msh5-Affect subsequent genome reorganization in Paramecium ...
Significance of Meiosis. Meiosis is the reduction division that occurs during gamete formation in sexually reproducing ... Significance of Meiosis Continued...... In the long term, if a species is to survive in a constantly changing environment and ... Meiosis I. 2 Cell Division occur.. Homologous chromosomes pair up and their chromatids wrap around each other and equivalent ... However, meiosis does more than halve the chromosomes into a cell, it also introduces genetic variation into gametes and ...
One of the pieces from the Covid Nova series. These represent nature on the cosmological scale but also on a microscopic level. Looking like planets or moons in space they are also represent nature at a cellular level where viruses can attack and replicate inside single cells or other genetic activity happens. Added to this, the work embodies the notion of songlines, dreamtime paths across the landscape that connect generations of people with their land and their creator spirits. The under painting contains pattern and texture suggesting genetic material or songlines, encapsulated in the glass-like resin. The black contains everything (absorbing all light and matter) and is all consuming, surrounding the particular, the circular image of gestures, marks, texture and colour.. ...
Ausführliche Informationen über die Forschungsinhalte der Arbeitsgruppe finden Sie auf unseren englischen Seiten.. ...
Meiosis I: - Splitting homologous pairs. - 2n --, n+n. *Meiosis II:. - Splitting chromatids. - n --, n+n: end result is 4 ... You can explain changes in DNA content during meiosis. *You can explain the importance of meiosis (in terms of genetic ... You can describe changes in number of chromosomes during meiosis. * ... You can list and describe the phases of meiosis. * ... Which best describes the number of chromosomes for Meiosis II? ...
"Meiosis" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject Headings) ... This graph shows the total number of publications written about "Meiosis" by people in this website by year, and whether " ... m6A modification of a 3 UTR site reduces RME1 mRNA levels to promote meiosis. Nat Commun. 2019 07 30; 10(1):3414. ... Cortical recruitment of centralspindlin and RhoA effectors during meiosis I of Caenorhabditiselegans primary spermatocytes. J ...
Category:. Videocreación (4´). Screenwritting and direction:. Estibaliz Urresola Solaguren. DoP:. Ibai Elorza. Editing:. Arnau Hernández. Synopsis:. Dr. Vapor or Mr. Stevenson, also named David Álvarez reflects on a question: what is creativity?. From his hand and through his voice, we delve into different creative processes that converge in the same reflection: creating is living consciously. ...
Answers are terms relating to sexual reproduction and meiosis ... The phase of meiosis in which sister chromatids line up in the ... Sexual Reproduction and Meiosis. Answers are terms relating to sexual reproduction and meiosis ... The phase of meiosis in which homologous chromosomes line up in the middle of the cell and a spindle fiber attaches to each one ... The phase of meiosis in which the sister chromatids of each duplicated chromosome are pulled to either end of the cell by ...
Meiosis - Complete Guide quantity. Add to cart. SKU: MEIOSIS Category: DNA, Cell Div & Reproduction Unit Tags: Life Science, ... Immerse your students in a dynamic learning experience with this comprehensive slide set on meiosis! Bursting with vibrant ...
Review of mitosis and meiosis. Mitosis and Meiosis Review multiple choice questions. ... Mitosis And Meiosis Review. Test Description: Review of mitosis and meiosis Instructions: Answer all questions to get your test ... 10) In females (humans), meiosis results in A. 4 equal size eggs. B. 1 egg and 3 polar bodies. C. 4 unequal size eggs. D. 4 ... 4) these are usually found at the opposite ends of a cell during mitosis or meiosis and they are used to help pull the cell ...
Which of the following are the differences between meiosis I and meiosis II? ... 6.5.2b Meiosis (Objective Questions). December 9, 2021. July 18, 2020. by ... If one of the homologous chromosome pairs does not separate during Meiosis I, how many chromosomes can be found in the gametes? ...
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Noticias • Meiosis: Cutting the ties that bind Meiosis: Cutting the ties that bind. 23 octubre 2014 The development of a new ... Those steps, known as reproductive cell division or meiosis, split the original number of chromosomes in half so that offspring ...
Meiosis generates haploid gametes, such as sperm and eggs, from a diploid cell such that a diploid genome is restored upon ... Meiosis generates haploid gametes, such as sperm and eggs, from a diploid cell such that a diploid genome is restored upon ... Meiosis produces gametes, such as eggs and sperm. Checkpoints monitor meiotic events to ensure that gametes have the correct ... The Synapsis Checkpoint in C. elegans Meiosis Bhalla, Needhi University of California Santa Cruz, Santa Cruz, CA, United States ...
... check out our detailed review of mitosis and meiosis - complete with helpful illustrations. ... What is Meiosis?Meiosis is a special type of cell division that creates gametes (sex cells). In meiosis, one cell with one full ... Mitosis and Meiosis Simulations: You can also use our Mitosis and Meiosis simulations as an effective review tool to review the ... Mitosis and meiosis are two of the most commonly misunderstood topics on the AP Biology exam. This complete review guide will ...
... during which phase of meiosis does the dna duplicate? anaphase 1interphasemetaphase 1prophase 1 ... the S phase of a cell cycle occurs during interphase, before mitosis or meiosis, and is responsible for the synthesis or ... The failure of one or more pairs of homologous chromosomes or sister chromatids to separate "normally" during meiosis is called ... The failure of one or more pairs of homologous chromosomes or sister chromatids to separate "normally" during meiosis is called ...
Purpose of Meiosis. Meiosis is a process that is important for sexual reproduction. During meiosis, one cell undergoes two cell ... Three Cells Undergo Meiosis. How Many Haploid Cells Are Produced?. If three cells undergo meiosis then there will be 12 haploid ... Three Cells Undergo Meiosis. How Many Haploid Cells Are Produced?. July 31, 2022. by Anonymous ...
Meiosis: The kind of cell division in which the nucleus of reproductive mother cell (2n) divides twice and chromosome divides ... Meiosis: The kind of cell division in which the nucleus of reproductive mother cell (2n) divides twice and chromosome divides ... It always occurs in reproductive mother cells (2n). For the lower type of plant (haploid plants) meiosis occurs in the zygote ( ... For the higher type of plants, meiosis occurs in reproductive mother cells in order to produce gametes before fertilization. ...
Summarize the inheritance of sex-linked traits through meiosis and how it relates to genetics. ...
GO:1905187: negative regulation of metaphase/anaphase transition of meiosis I (Biological process). Any process that stops, ... prevents or reduces the frequency, rate or extent of metaphase/anaphase transition of meiosis I. [GO_REF:0000058, GOC: ...
Dive into the research topics of Meisetz, a novel histone tri-methyltransferase, regulates meiosis-specific epigenesis. ...
  • Mitosis and meiosis are two of the most commonly misunderstood topics on the AP Biology exam. (labster.com)
  • This complete review guide will give you a crash course in mitosis and meiosis stages, and highlight the key differences between mitosis and meiosis. (labster.com)
  • If you are learning for the first time, skip the written study guide and go straight to our mitosis and meiosis simulations. (labster.com)
  • The best way to remember mitosis and meiosis is to understand the ways in which they are different. (labster.com)
  • If you can remember the following five conceptual differences between mitosis and meiosis, you'll be all set for the exam. (labster.com)
  • Drawing both processes out on paper is a good practice exercise to deepen your understanding of mitosis and meiosis. (labster.com)
  • You can also use our Mitosis and Meiosis simulations as an effective review tool to review the material and to quiz yourself. (labster.com)
  • A cell cycle process comprising the steps by which a cell progresses through male meiosis II, the second meiotic division in the male germline. (mcw.edu)
  • If the egg is fertilized by a sperm, it will undergo the second meiotic division to complete meiosis and form a mature egg. (reproduction-online.org)
  • Because the number of chromosomes is halved during meiosis, gametes can fuse (i.e. fertilization) to form a diploid zygote that contains two copies of each chromosome, one from each parent. (wikipedia.org)
  • Meiosis produces haploid gametes (ova or sperm) that contain one set of 23 chromosomes. (wikipedia.org)
  • Meiosis is a germ-cell-specific cell division process through which haploid gametes are produced for sexual reproduction. (nih.gov)
  • For more than 15 years, Dernburg has aimed that laserlike focus on meiosis-the two-part cell division process that reduces diploid germline cells to haploid gametes (such as ova and sperm)-using C. elegans as a model system. (the-scientist.com)
  • A: Meiosis occurs in gonads because these specialized organs are responsible for the production of gametes, which are necessary for sexual reproduction. (reproduction-online.org)
  • Meiosis ensures that the resulting gametes have half the number of chromosomes as the parent cell. (reproduction-online.org)
  • For example, nondisjunction, where chromosomes fail to separate correctly during meiosis, can result in the production of gametes with an abnormal number of chromosomes. (reproduction-online.org)
  • If one of the homologous chromosome pairs does not separate during Meiosis I, how many chromosomes can be found in the gametes? (onlinetuition.com.my)
  • Meiosis generates haploid gametes, such as sperm and eggs, from a diploid cell such that a diploid genome is restored upon fertilization. (grantome.com)
  • These complementary approaches will enable us to gain a molecular and mechanistic understanding of how homolog synapsis is monitored during meiosis and how an unsynapsed or inappropriately synapsed homolog generates a checkpoint signal that is ultimately translated into an apoptotic response to avoid the production of aneuploid gametes. (grantome.com)
  • Meiosis produces gametes, such as eggs and sperm. (grantome.com)
  • What is Meiosis?Meiosis is a special type of cell division that creates gametes (sex cells). (labster.com)
  • In meiosis, one cell with one full set of DNA becomes four gametes. (labster.com)
  • Later on, during fertilisation, the haploid cells produced by meiosis from a male and a female will fuse to create a cell with two copies of each chromosome again, the zygote. (wikipedia.org)
  • In most organisms, these links can help direct each pair of homologous chromosomes to segregate away from each other during meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell. (wikipedia.org)
  • Meiosis is a complex process that involves two rounds of cell division, resulting in the formation of four genetically unique haploid cells. (reproduction-online.org)
  • However, the key difference is that in meiosis II, the sister chromatids separate instead of homologous chromosomes. (reproduction-online.org)
  • The phase of meiosis in which duplicated chromosomes condense, homologous chromosomes form pairs, the nucleolus disappears and the nuclear membrane breaks down. (amazonaws.com)
  • The phase of meiosis in which homologous chromosomes line up in the middle of the cell and a spindle fiber attaches to each one. (amazonaws.com)
  • Using a loss-of-function approach in mice, here we show that the 5mC-specific dioxygenase Tet1 has an important role in regulating meiosis in mouse oocytes. (nih.gov)
  • The two meiotic divisions are known as meiosis I and meiosis II. (wikipedia.org)
  • This same pattern, but not the same number of chromosomes, occurs in all organisms that utilize meiosis. (wikipedia.org)
  • Meiosis occurs in all sexually-reproducing single-celled and multicellular organisms (which are all eukaryotes), including animals, plants and fungi. (wikipedia.org)
  • Meiosis Occurs In Specialized Animal Organs Known As Gonads. (reproduction-online.org)
  • In males, meiosis occurs in the testes, specifically in cells called spermatocytes. (reproduction-online.org)
  • In females, meiosis occurs in the ovaries, specifically in cells called oocytes. (reproduction-online.org)
  • A: While meiosis primarily occurs in gonads, there are exceptions. (reproduction-online.org)
  • Meiosis is a remarkable process that occurs in the specialized organs known as gonads in animals. (reproduction-online.org)
  • Meiosis is the reduction division that occurs during gamete formation in sexually reproducing organisms. (getrevising.co.uk)
  • the S phase of a cell cycle occurs during interphase, before mitosis or meiosis, and is responsible for the synthesis or replication of DNA. (turito.com)
  • Many plant cells go straight into Meiosis II with no formation of the spindle. (getrevising.co.uk)
  • The phase of meiosis in which the sister chromatids of each duplicated chromosome are pulled to either end of the cell by spindle fibers. (amazonaws.com)
  • A mutation in the spindle checkpoint arresting meiosis II in Brachiaria ruziziensis. (bvsalud.org)
  • Although the process of meiosis is related to the more general cell division process of mitosis, it differs in two important respects: Meiosis begins with a diploid cell, which contains two copies of each chromosome, termed homologs. (wikipedia.org)
  • However, meiosis in females is unique because it is arrested at prophase I until puberty. (reproduction-online.org)
  • Although several epigenetic regulators, such as Dnmt3l and the histone methyltransferases G9a and Prdm9, have been reported to be crucial for meiosis, little is known about how the expression of meiotic genes is regulated and how their expression contributes to normal meiosis. (nih.gov)
  • We will determine how the assembly of the synaptonemal complex (SC) is monitored during a normal meiosis by localizing PCH-2 in wildtype and mutant backgrounds, identifying proteins that interact with PCH-2 and investigating whether PCH-2 specifically modifies an important class of SC components. (grantome.com)
  • Before the initiation of meiosis, mouse primordial germ cells undergo a series of epigenetic reprogramming steps, including the global erasure of DNA methylation at the 5-position of cytosine (5mC) in CpG-rich DNA. (nih.gov)
  • In mammals, spermatogenesis is a cyclical process that involves differentiation of spermatogonia into spermatocytes, which undergo meiosis to form haploid spermatids and ultimately spermatozoa ( Griswold, 2016 ). (elifesciences.org)
  • Spermatocytes undergo meiosis to produce four haploid sperm cells. (reproduction-online.org)
  • Some species, such as certain fungi and plants, can undergo meiosis in specialized structures other than gonads. (reproduction-online.org)
  • Only one oocyte will continue meiosis each month, while the remaining oocytes degenerate. (reproduction-online.org)
  • The division of the oocyte during meiosis produces one large egg cell (secondary oocyte) and one small polar body. (reproduction-online.org)
  • Differentiating spermatogonia give rise to spermatocytes that cross the BTB and complete meiosis. (elifesciences.org)
  • Cortical recruitment of centralspindlin and RhoA effectors during meiosis I of Caenorhabditiselegans primary spermatocytes. (uchicago.edu)
  • Thus, alternating cycles of meiosis and fertilization enable sexual reproduction, with successive generations maintaining the same number of chromosomes. (wikipedia.org)
  • DS originates from the inadequate separation of chromosome 21, which may occur in the gamete formation phase (egg or sperm) or immediately after fertilization in meiosis or in mitosis, respectively. (bvsalud.org)
  • The development mechanism of this genetic abnormality is related to the non-disjunction of the genetic material during meiosis, however its true incidence is still unknown 1-2 . (bvsalud.org)
  • Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. (wikipedia.org)
  • In parthenogenesis, an individual is formed from an unfertilized OVUM that did not complete MEIOSIS. (bvsalud.org)
  • It includes meiosis, Mendelian inheritance, linkage analysis and population genetics. (lu.se)
  • Inherited genetic effects pertain to somatic and germ cell DNA transmitted through mitosis or meiosis, respectively. (cdc.gov)
  • In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells, each with half the number of chromosomes as the original parent cell. (wikipedia.org)
  • The phase of meiosis in which a nuclear membrane forms around each groups of chromosomes and cytoplasm divides in cytokinesis making two new daughter cells. (amazonaws.com)
  • Cells with scattered chromosomes were unable to progress in meiosis . (bvsalud.org)
  • Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids, which remain held together through sister chromatid cohesion. (wikipedia.org)
  • The phase of meiosis in which chromosome pairs are pulled to opposite ends of the cell. (amazonaws.com)
  • The phase of meiosis in which chromosomes do not divide and sister chromatids remained condensed and thickened. (amazonaws.com)
  • The phase of meiosis in which sister chromatids line up in the middle of the cell in single file. (amazonaws.com)
  • During which phase of meiosis does the dna duplicate? (turito.com)
  • Meiosis is part of the Nuclear Stock Association Group. (niab.com)
  • The Nuclear Stock Association Group, through its Meiosis and Terraplanta subsidiaries, specialises in the international management of IP, High Health planting stock and propagation. (niab.com)
  • m6A modification of a 3' UTR site reduces RME1 mRNA levels to promote meiosis. (uchicago.edu)
  • Meiosis I had a low frequency of abnormalities , mainly related to the chiasma terminalization process. (bvsalud.org)
  • Usually the Chromosomes stay in their condensed form and Meiosis II follows on immediately. (getrevising.co.uk)
  • A: Meiosis promotes genetic diversity through the processes of genetic recombination and independent assortment. (reproduction-online.org)
  • During meiosis II, the cohesion between sister chromatids is released and they segregate from one another, as during mitosis. (wikipedia.org)
  • Immerse your students in a dynamic learning experience with this comprehensive slide set on meiosis! (sciencebc.ca)