During Anaphase, what occurs?

• A. The nuclear envelope fragments and spindles attach to kinetochores
• B. Chromosomes line up in the middle
• C. Chromosomes separate and move to opposite ends of the cell
• D. The spindle forms

Answer: (C)

During Anaphase, the sister chromatids separate and are pulled toward opposite poles of the cell. This separation happens as kinetochore microtubules shorten, pulling the chromatids apart, while motor proteins at the poles push the cell ends further apart by lengthening non-kinetochore microtubules. The result is that each pole ends up with a complete set of chromosomes. The breakdown of the nuclear envelope and chromosomes lining up at the center occur earlier in mitosis (prophase/prometaphase and metaphase, respectively), and spindle formation happens before chromosomes are aligned.