Question

1. Each of the following is an activity of a microtubule motor protein during mitosis except
   1. shortening kinetochore microtubules.
   2. pulling kinetochore microtubules in at centrosomes.
   3. pushing interpolar microtubules for anaphase B.
   4. pulling astral microtubules toward the cell cortex.
   5. All of the above are activities of microtubule motors.

Answer 1

Correct option is e) all of the above are activities of microtubule motors.

The rearangement of microtubule subunit is fundamental for the formation of mitotic spindle during mitosis. During metaphase, chromosome arrange at the equator. each chromosome has atleast two microtubules extending from its kinetochore. Kinetochore microtubule attach the chromosome to the spindle pole. Interpolar microtubule extend from the spindle pole across the equator. Astral microtubule etend from the spindle pole to the cell membrane.

During anaphase A, kinretochore microtubule shortens and draw chromosome towards spindle poles. In anaphase B, astral microtubule pulls the poles further apart and interpolar microtubules slides past eachother, exerting aditional pull on the chromosome.