Final answer:
Anaphase is the process of chromosomes, lined up at the cell's equator, being pulled apart into individual sister chromatids, which are then rapidly moved to opposite poles of the cell.
Step-by-step explanation:
The process being described is anaphase, a stage of cell division, or mitosis, where chromosomes that have lined up at the cell's equator are pulled apart. During metaphase, chromosomes, consisting of sister chromatids, line up at the cell's equator. Then, in anaphase, these sister chromatids are separated as spindle fibers pull them apart and toward opposite poles of the cell. In this phase, the cohesin proteins degrade, and the chromatids, now individual chromosomes, move rapidly toward the centrosomes. This results in the cell elongating and taking on an oval shape.