Question

QUESTION 1 Maturation promoting factor (MPF) is a/an: Phase of the cell cycle O Activity O Protein O All of the above QUESTION 2 Which microtubules do shorten during anaphase? astral O Kinetochore O Polar Astral and kinetochore

Answer 1

2. Answer is kinetochore. Metaphase leads to anaphase, during which each chromosome's sister chromatids separate and move to opposite poles of the cell. Enzymatic breakdown of cohesin — which linked the sister chromatids together during prophase — causes this separation to occur. Upon separation, every chromatid becomes an independent chromosome. Meanwhile, changes in microtubule length provide the mechanism for chromosome movement. More specifically, in the first part of anaphase — sometimes called anaphase A — the kinetochore microtubules shorten and draw the chromosomes toward the spindle poles. Then, in the second part of anaphase — sometimes called anaphase B — the astral microtubules that are anchored to the cell membrane pull the poles further apart and the interpolar microtubules slide past each other, exerting additional pull on the chromosomes.

1. Answer is protein. Maturation promoting factor is the cyclin-Cdk complex that was discovered first in frog eggs. It stimulates the mitotic and meiotic phases of the cell cycle. MPF promotes the entrance into mitosis (the M phase) from the G₂phase by phosphorylating multiple proteins needed during mitosis.

It functions are :

• Triggers the formation of mitotic spindle through microtubule instability.
• Promotes mitosis i.e. chromatin condensation through phosphorylation of condensins.