Anafaasi

Anafaasi, commonly referred to in English as anaphase, is a stage of cell division in which sister chromatids separate and move toward opposite poles. It occurs during mitosis and during the second division of meiosis. During mitotic anaphase, cohesin proteins that hold sister chromatids together are cleaved, typically by the protease separase activated by the anaphase-promoting complex/cyclosome (APC/C).

Once separated, chromatids are pulled toward the poles by shortening of kinetochore microtubules, while polar microtubules lengthen to push the poles further apart. Anaphase can be subdivided into Anaphase A, involving chromosome movement toward the poles, and Anaphase B, involving spindle elongation and increased pole separation. Motor proteins such as dynein and various kinesins contribute to these movements.

In meiosis, the process differs between divisions: Anaphase I separates homologous chromosomes, reducing the chromosome number by half, while Anaphase II separates sister chromatids, similar to mitotic anaphase, restoring the single-chromatid state in each daughter cell.

The onset of anaphase is tightly regulated to ensure equal genetic material is distributed. Checkpoints monitor chromosome alignment and spindle integrity, delaying progression if errors are detected. Proper execution of anaphase is essential for genomic stability; failures can lead to aneuploidy and developmental abnormalities. Anaphase is followed by telophase, during which the nuclear envelope re-forms and cytokinesis typically completes cell division.