The decline of MPF activity at the end of mitosis is due toa. the destruction of the protein kinase Cdk.b. decreased synthesis of Cdk.c. the degradation of cyclin.d. the accumulation of cyclin.

Verified step by step guidance

1. Understand that MPF (Maturation Promoting Factor) is a complex of cyclin and Cdk (cyclin-dependent kinase) that regulates the cell cycle.
2. Recognize that the activity of MPF is dependent on the presence of cyclin, which binds to Cdk to activate it.
3. Recall that at the end of mitosis, the cell needs to transition to the next phase, which requires the inactivation of MPF.
4. Consider that the degradation of cyclin leads to the inactivation of MPF, as Cdk alone is inactive without cyclin.
5. Conclude that the decline of MPF activity at the end of mitosis is due to the degradation of cyclin, which is option c.

Key Concepts

Maturation Promoting Factor (MPF)

Maturation Promoting Factor (MPF) is a complex of cyclin and cyclin-dependent kinase (Cdk) that regulates the cell cycle, particularly the transition from G2 phase to mitosis. MPF activity is crucial for the initiation of mitosis, and its levels fluctuate throughout the cell cycle, peaking during mitosis.

Cyclin Degradation

Cyclins are regulatory proteins whose levels rise and fall throughout the cell cycle. At the end of mitosis, cyclins are targeted for degradation, leading to a decrease in MPF activity. This degradation is essential for the exit from mitosis and the progression into the next cell cycle phase.

Cyclin-Dependent Kinase (Cdk)

Cyclin-dependent kinases (Cdks) are enzymes that, when activated by binding to cyclins, phosphorylate target proteins to drive the cell cycle forward. The activity of Cdks is tightly regulated by the availability of cyclins and their degradation, which is critical for ensuring proper cell cycle progression and preventing uncontrolled cell division.