Final answer:
During anaphase A of cell division, sister chromatids are separated and move toward opposite poles of the cell due to the shortening of kinetochore microtubules, a process known as poleward flux. The force generated by the microtubule disassembly at the centrioles or MTOCs pulls the chromosomes apart. Polar microtubules also contribute to cell elongation and separation of the poles.
Step-by-step explanation:
During anaphase A, the separation of sister chromatids occurs. This is a critical process in cell division where spindle fibers, consisting of microtubules, shorten and pull the sister chromatids toward the opposite poles of the cell. The kinetochore microtubules are responsible for this movement. At their respective kinetochores, where they are anchored, these microtubules disassemble at their minus ends near the centrioles or microtubule-organizing centers (MTOCs). This disassembly process is referred to as the poleward flux, which generates the force needed for the movement of chromosomes.
Polar microtubules, which extend between the poles but do not bind to kinetochores, also play a role during anaphase. They overlap at the metaphase plate and slide past each other, driven by motor proteins like dynein, facilitating the elongation of the cell and aiding in the physical separation of the poles.
The coordinated shortening of kinetochore microtubules and the action of polar microtubules are essential for the proper segregation of chromosomes to the daughter cells, ensuring that each new cell receives an identical set of genetic material.