• mitosis
  • In mitosis, the spindle assembly checkpoint (SAC) controls the proper attachment to and alignment of chromosomes on the spindle. (frontiersin.org)
  • Joe Hin Tjio working in Albert Levan's lab was responsible for finding the approach: Using cells in culture Pre-treating cells in a hypotonic solution, which swells them and spreads the chromosomes Arresting mitosis in metaphase by a solution of colchicine Squashing the preparation on the slide forcing the chromosomes into a single plane Cutting up a photomicrograph and arranging the result into an indisputable karyogram. (wikipedia.org)
  • All chromosomes normally appear as an amorphous blob under the microscope and only take on a well defined shape during mitosis. (wikipedia.org)
  • It is entirely coincidental that the Y chromosome, during mitosis, has two very short branches which can look merged under the microscope and appear as the descender of a Y-shape. (wikipedia.org)
  • congenital
  • Significant causes of morbidity and mortality in trisomy 21 are congenital heart defects (CHDs), esophageal atresia with or without tracheoesophageal fistula, duodenal atresia, and/or Hirschsprung disease. (renalandurologynews.com)
  • species
  • The number of chromosomes is different for different species. (wikipedia.org)
  • Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. (wikipedia.org)
  • genes
  • The increased gene dosage of three X/Y chromosome pseudoautosomal region (PAR1) SHOX genes has been postulated as a cause of the increased stature seen in all three sex chromosome trisomies: 47,XXX, 47,XXY, and 47,XYY. (wikipedia.org)
  • Autosomes still contain sexual determination genes even though they are not sex chromosomes. (wikipedia.org)
  • In 1931, McClintock and Harriet Creighton demonstrated that cytological recombination of marked chromosomes correlated with recombination of genetic traits (genes). (wikipedia.org)
  • It represents about 800 protein-coding genes compared to the Y chromosome containing about 70 genes, out of 20,000 - 25,000 total genes in the human genome. (wikipedia.org)
  • Genetic disorders that are due to mutations in genes on the X chromosome are described as X linked. (wikipedia.org)
  • The X chromosome carries hundreds of genes but few, if any, of these have anything to do directly with sex determination. (wikipedia.org)
  • gene
  • For example, the SRY gene on the Y chromosome encodes the transcription factor TDF and is vital for male sex determination during development. (wikipedia.org)
  • Campomelic dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene. (wikipedia.org)
  • Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. (wikipedia.org)
  • Known human disorders include Charcot-Marie-Tooth disease type 1A, which may be caused by duplication of the gene encoding peripheral myelin protein 22 (PMP22) on chromosome 17. (wikipedia.org)
  • In squamous cell carcinoma, a protein from the epidermal growth factor receptor (EGFR) gene is often overexpressed in conjunction with polysomy of chromosome 7, so chromosome 7 can be used to predict the presence of EGFR in squamous cell carcinoma. (wikipedia.org)
  • Overexpression of the HER2/neu gene on chromosome 17 and some type of polysomy has been reported in 8-68% of breast carcinomas. (wikipedia.org)
  • The following are some of the gene count estimates of human X chromosome. (wikipedia.org)
  • Variations
  • Conditions resulting from X and Y chromosome variations remain frequently undiagnosed by physicians. (genetic.org)
  • Our purpose at AXYS is to be that resource for the spectrum of X and Y chromosome variations. (genetic.org)
  • What are X & Y chromosome variations? (genetic.org)
  • Children are born with X&Y chromosome variations, but these conditions are typically not inherited. (genetic.org)
  • They also work to create one-on-one plans that help children with X & Y chromosome variations and other rare disorders grow and learn in the way that works best for them. (wikipedia.org)
  • Most health care practitioners are not well versed in chromosome variations and therefore they don't even consider testing for X & Y chromosome variations when caring for a child that is presented with developmental concerns. (wikipedia.org)
  • X & Y chromosome variations are beginning to be more widely known and tested for nationwide. (wikipedia.org)
  • It detects genomic copy number variations at a higher resolution level than conventional karyotyping or chromosome-based comparative genomic hybridization (CGH). (wikipedia.org)
  • karyotypes
  • Conventional karyotypes can assess the entire genome for changes in chromosome structure and number, but the resolution is relatively coarse, with a detection limit of 5-10Mb. (wikipedia.org)
  • cell
  • If a sperm or egg cell with too many or too few chromosomes participates in fertilization, it will produce a zygote with too many or too few chromosomes. (pearltrees.com)
  • During cell division the material composing the chromosome is compactly coiled, making it visible with appropriate staining and permitting its movement in the cell with minimal entanglement. (thefreedictionary.com)
  • It is also possible to make a photomicrograph of a cell nucleus, cut it apart, and rearrange it so that the individual chromosomes are in order and labeled. (thefreedictionary.com)
  • Here, we summarize the main differences between mitotic and meiotic cell divisions, and explain why meiotic divisions pose special challenges for correct chromosome segregation. (frontiersin.org)
  • Occasionally, because of problems with the formation of a parent's sperm or egg, or due to errors in cell division after the embryo is fertilized, a child can be born with extra or too few sex chromosomes. (genetic.org)
  • Instead, they are caused by a problem in the division of the X and Y chromosomes during the formation of a parent's egg or sperm, or by errors in cell division after the embryo is fertilized. (genetic.org)
  • Most organisms that reproduce sexually have pairs of chromosomes in each cell, with one chromosome inherited from each parent. (wikipedia.org)
  • If the chromosome pairs fail to separate properly during cell division, the egg or sperm may end up with a second copy of one of the chromosomes. (wikipedia.org)
  • When predicting the likely effects (if any) of CPM detected in the first trimester, several potentially interactive factors may be playing a role, including: Origin of error: Somatic errors are associated with lower levels of trisomy in the placenta and are expected usually to involve only one cell line (i.e.: the trophoblast cells or the villus stroma cells). (wikipedia.org)
  • All human autosomes have been identified and mapped by extracting the chromosomes from a cell arrested in metaphase or prometaphase and then staining them with some sort of dye (most commonly, Giemsa). (wikipedia.org)
  • Each person usually has one pair of sex chromosomes in each cell. (wikipedia.org)
  • pairs
  • Karyograms and staining techniques can only detect large-scale disruptions to chromosomes-chromosomal aberrations smaller than a few million base pairs generally cannot be seen on a karyogram. (wikipedia.org)
  • inheritance
  • McClintock continued her career in cytogenetics studying the mechanics and inheritance of broken and ring (circular) chromosomes of maize. (wikipedia.org)
  • Autopolyploids may show polysomic inheritance of all the linkage groups, and their fertility may be reduced due unbalanced chromosome numbers in the gametes. (wikipedia.org)
  • Luke Hutchison noticed that a number of possible ancestors on the X chromosome inheritance line at a given ancestral generation follows the Fibonacci sequence. (wikipedia.org)
  • microarray
  • Other terms used to describe the arrays used for karyotyping include SOMA (SNP oligonucleotide microarrays) and CMA (chromosome microarray). (wikipedia.org)