Microtubules

ID #2285

I just want to make sure this is right: Kinesin and dyenin move sister chromatids until they line up at the metaphase plate. Then during anaphase A, sister chromatids move to opposite poles via kinetochore microtubules. During anaphase B, spindles distance themselves from each other, further separating sister chromatids. During the entirety of anaphase, kinesins and dyenins are not going to move. The microtubules now move.


You basically have it, but I want to clarify a couple of things. During Anaphase A the sister chromatids will move via the kinetochore microtubules, but it will be the dyneins that assist in the process. Dyneins move towards the minus ends of MTs, which are anchored in the spindle poles, so dyneins will be moving the sister chromatids towards the poles (and the kinetochore MTs will depolymerize behind the movement once they are no longer required). In this case, the dyneins will be moving. However, during Anaphase B, even though the kinesins on polar MTs and the dyneins on the astral MTs perform their job of "walking" towards their respective ends, these motor protein are anchored in place. So in this case, the polar and astral MTs are doing the relative movement and would appear to "push" and "pull" the spindle poles, respectively. You are correct that kinesins and dyneins located in the kinetochore will be involved in moving the sister chromatids along the metaphase plate. 

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