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Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregation process occurs during both mitosis and meiosis. Chromosome segregation also occurs in prokaryotes ...
To ensure that chromosome segregation takes place correctly, cells have developed a precise and complex mechanism. In the first place, cells must coordinate centrosome duplication with DNA replication, and a failure in this coordination will generate monopolar or multipolar mitotic spindles, which generally will produce abnormal chromosome ...
Figure 1. An interphase nucleus (left) and a set of mitotic chromosomes (right) from human tissue culture cells. Bar, 10 μm. Condensins are large protein complexes that play a central role in chromosome assembly and segregation during mitosis and meiosis (Figure 1).
The function or significance of mitosis, is the maintenance of the chromosomal set; each formed cell receives chromosomes that are alike in composition and equal in number to the chromosomes of the parent cell. Mitosis occurs in the following circumstances: Development and growth: The number of cells within an organism increases by mitosis.
Nondisjunction of sister chromatids during mitosis: Left: Metaphase of mitosis. Chromosome line up in the middle plane, the mitotic spindle forms and the kinetochores of sister chromatids attach to the microtubules. Right: Anaphase of mitosis, where sister chromatids separate and the microtubules pull them in opposite directions.
Proper biorientation allows correct chromosomal segregation in cell division. [3] Although this process is not well understood, high-resolution imaging of live mouse oocytes has revealed that chromosomes form an intermediate chromosomal configuration, called the prometaphase belt , which occurs prior to biorientation.
Meiotic recombination allows a more independent segregation between the two alleles that occupy the positions of single genes, as recombination shuffles the allele content between homologous chromosomes. Recombination results in a new arrangement of maternal and paternal alleles on the same chromosome.
The proteins encoded by these genes all function in the chromosome cohesion pathway that is employed in the cohesion of sister chromatids during mitosis, DNA repair, chromosome segregation and the regulation of developmental gene expression. Defects in these functions likely underlie many of the features of Cornelia de Lang Syndrome.