Describe the key events of anaphase and telophase.
Metaphase ends and anaphase begins as the centromeres of each pair of chromatids split, effectively doubling the number of chromosomes. Once separated, sister chromatids, each now an independent chromosome with its own centromere, begin moving apart toward opposite poles of the cell. The movement is made possible via two mechanisms. The kinetochore fibers attached to each centromere begin to shorten, pulling the chromosomes toward the poles. At the same time, the polar microtubules from opposite ends of the cell form cross bridges in the equatorial plane, pushing the poles apart by becoming longer. In telophase, the spindle apparatus disappears, a nuclear membrane reforms around both sets of chromosomes, which by now have reached their respective poles, and the centrioles replicate. The chromosomes uncoil to resume their active interphase form, and the nucleoli reappear.
