Fluctuations in the amount of cell-cycle control molecules affect the rate of the cell cycle. Which of the following would slow the cell cycle?
A) Kinases become activated by cyclins, and inhibit mitosis.
B) Cyclins accumulate during the G1, S, and G2 phases and inhibit MPF.
C) MPF is turned off, which leads to the destruction of cyclin.
D) At the G2 checkpoint, MPF complexes form as aggregations of Cdk and cyclin.
Answer: D) At the G2 checkpoint, MPF complexes form as aggregations of Cdk and cyclin.