Question

The decline of MPF activity at the end of mitosis is due to

(A) the destruction of the protein kinase CDK.

(B) decreased synthesis of Cdk.

(C) degradation of cyclin

(D) accumulation of cyclin.

Short answer

(A) The option “the destruction of the protein kinase CDK” is false.

(B) The option “decreased synthesis of Cdk” is false.

(C) The option “degradation of cyclin” is true.

(D) The option “accumulation of cyclin” is false.

Step-by-step solution

Description of cell division

Every organism tends to grow depending upon the available favorable factors. The growth occurs due to the process of cell division, such as mitosis and meiosis. Mitosis takes place in the normal cells. Meiosis occurs in the gametes.

Explanation of option (A)        

Protein kinase CDK is the kinase that regulates the transcription mechanism. It also controls the cell division process.

The maturation promotion factors are not related to the protein kinases.

Therefore, the given statement is false.

Explanation of option (B)

The cyclin-dependent kinases are the protein kinases that are involved in mitosis. These kinases get attached to the cyclin molecules to get activated.

The maturation promoting factor is not dependent on the cdks alone. So, the decline in the MPF does not take place only with the decreased production of cdks.

Therefore, the given statement is false.

Explanation of option (C)

The mitosis promoting factor has kinase activity. In order to perform the kinase activity, there is a need for cyclins. Cycling is the regulatory protein for the cell cycle progression.

The degradation of cyclin can, in turn, lead to a decline in MPF at the mitosis.

Therefore, the given statement is true.

Explanation of option (D)

Accumulation of cyclin tends to increase the kinase activity of mitosis promoting factor. It does not cause a decline in the MPF.

The accumulation of cyclin can increase the activity of mitosis-promoting factors.

Therefore, the given statement is false