Flexi Says: Anaphase is the phase in which the sister chromatids separate. The sister chromatids are pulled apart by the shortening of the microtubules of the spindles, similar to the reeling in of a fish by the shortening of the fishing line. One sister chromatid moves to one pole of the cell, and the other sister chromatid moves to the opposite pole. This process occurs when the proteins that bind sister chromatids together are cleaved, resulting in unattached identical chromosomes, essentially separate daughter chromosomes. These separate chromosomes are pulled apart by shortening spindle fibers, and pulled toward the centrosomes to which they are attached. At the end of anaphase the spindle fibers degrade. At this time, each pole of the cell has a complete set of chromosomes, identical to the amount of DNA at the beginning of G1 of the cell cycle.