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Sister chromatid cohesion is essential for the correct distribution of genetic information between daughter cells and the repair of damaged chromosomes. Defects in this process may lead to aneuploidy and cancer, especially when checkpoints fail to detect DNA damage or when incorrectly attached mitotic spindles do not function properly.
During cell division, the identical copies (called a "sister chromatid pair") are joined at the region called the centromere (2). Once the paired sister chromatids have separated from one another (in the anaphase of mitosis ) each is known as a daughter chromosome.
Image of kinetochores in pink. A kinetochore (/ k ɪ ˈ n ɛ t ə k ɔːr /, /-ˈ n iː t ə k ɔːr /) is a flared oblique-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers, which can be thought of as the ropes pulling chromosomes apart, attach during cell division to pull sister chromatids apart. [1]
However, in the G2 stage of the cell cycle (following DNA replication), a second homologous DNA molecule is also present: the sister chromatid. Evidence indicates that, due to the special nearby relationship they share, sister chromatids are not only preferred over distant homologous chromatids as substrates for recombinational repair, but have ...
In this diagram of a duplicated chromosome, (2) identifies the centromere—the region that joins the two sister chromatids, or each half of the chromosome. In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers. The centromere links a pair of sister chromatids together during cell ...
Cohesin is a protein complex that mediates sister chromatid cohesion, homologous recombination, and DNA looping. Cohesin is formed of SMC3, SMC1, SCC1 and SCC3 (SA1 or SA2 in humans). Cohesin holds sister chromatids together after DNA replication until anaphase when removal of cohesin leads to separation of sister chromatids. The complex forms ...
The sister chromatids will be distributed to each daughter cell at the end of the cell division. Whereas if the chromosome is isobrachial (centromere at centre and arms of equal length), the p and q system is meaningless. At either end of a chromosome is a telomere, a cap of DNA that protects the rest of the chromosome from damage.
Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called ...