Question

1a. There is a defect in one of the proteins that make up the kinetochore such that the kinetochore cannot function. As a result, the mitotic cell cycle is blocked. What stage will the cycle stop at? Explain your reasoning.

1b. What would happen to the amount of protein made per mRNA molecule is the enzyme Poly A Polymerase is defective? Explain your reasoning.

Answer 1

If the kinetochore is mutated and not working, the cell cycle will stop at prometaphase/metaphase. This is because it is during prometaphase that kinetochore appears and microtubules attach themselves to the kinetochore. If cell detects that microtubules aren't attached to the kinetochore, it initiates spindle checkpoint signal and the cell cycle will not move to the anaphase.

Question 1b)

Role of Poly A tail in an mRNA is to provide stability as well as to prevent its degradation by nucleases in the Cytosol. So if Poly A polymerase is defective, it will effect the stability in a negative manner and protein expression will lower down.

This mean that amount of protein made per mRNA molecule will be lower than the normal situation.