The Cell Cycle and Events of M-Phase

ID #1369

I am confused about the function of the kinetochores. In addition, during Anaphase A, how are the chromatids moving to the poles via the kinetochore?

The kinetochores allow a place for MTs to attach and provide the motor proteins that are necessary to get pairs of sister chromatids lined up during prometaphase. Once anaphase is reached, it's now time to separate the sister chromatids, and this happens by what looks like the MTs pulling each sister chromatid to opposite poles. In reality, as with any cytoskeleton/motor protein combination, it's the motor doing the moving, not the highway (cytoskeleton). Specifically, if only the dyneins in a kinetochore are engaged, they will "walk" toward the minus ends of the kinetochore MTs, which are anchored into the centrosome. This pulls the chromatid toward the centrosome. The reason it looks like the MT is doing the pulling is because the plus end of the MT is depolymerized once the dyneins have "walked" past it -- that region is not needed anymore.

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