Final answer:
Anaphase is the phase in mitosis when genetically identical chromosomes, which were previously sister chromatids, are separated and pulled towards opposite poles of the cell.
Step-by-step explanation:
The phase during which genetically identical chromosomes (previously known as sister chromatids) move to opposite poles is known as anaphase. This is the third phase of mitosis, a critical process for cell division. During anaphase, the connection between the sister chromatids breaks down as the centromeres divide, and the microtubules pull the chromosomes toward opposite poles of the cell. As the spindle fibers shorten, much like reeling in a fish, one chromatid moves to one pole, and the other moves to the opposite pole. At the end of anaphase, each pole contains a complete set of chromosomes.