Final answer:
During anaphase in mitosis, sister chromatids are separated as spindle fibers shorten and pull them towards opposite cell poles, ensuring each new daughter cell has identical genetic material.
Step-by-step explanation:
Anaphase and Chromosome Separation
During anaphase, which is the third stage of mitosis, a critical process occurs where sister chromatids are split apart. Initially connected at the centromere, the cohesin proteins degrade allowing the sister chromatids to separate. Each of these now individual chromosomes is pulled towards opposite poles of the cell by the shortening of spindle fibers, similar to reeling in a fishing line. This results in each pole receiving an identical set of chromosomes. The entire cell elongates due to the sliding of non-kinetochore microtubules at the metaphase plate where they overlap. It's important to note that during anaphase I of meiosis, microtubules pull the linked (homologous) chromosomes apart while sister chromatids stay attached at the centromere. The separation of chromosomes ensures that two new daughter cells will have the same genetic composition.