You have isolated a strain of mutant yeast cells that divides normally at 2 5 C but cannot enter M phase at 3 7 C . You found that the gene for M Cdk is not mutated. Which of the following temperature-sensitive mutations could be responsible for the behavior of this strain of yeast? Inactivation of an enzyme that normally degrades M-cyclin. Inactivation of a protein that normally triggers the synthesis of M-cyclin. Inactivation of a protein kinase that normally inactivates the Cdk. None of the above.