Which of the following cyclin molecules is essential to activate pre-replication complexes (pre-RCs) ?

a. Cyclin A

b. Cyclin B

c. Cyclin C

d. Cyclin D

e. Cyclin E

a. Cyclin A

Explanation:

Cyclin A -

Cyclin A is one of the species of the family cyclin, which is a collection of proteins whose function is regulating the progression of the cell cycle.

The stages via which a cell pass are culminate in its division and replication are collectively are called the cell cycle.

As we know, the successful replication and division of a cell is important for the survival of the cell, the cell cycle is regulated by many components for the error - free and efficient progression of the cell cycle.

Answer: Yes definitely Cyclin A

Explanation: The concentrations of cyclin A peak during the G2 stage, suggesting that the start of this stage is triggered by high concentrations of the Cdkcs it forms. Similarly, cyclin A vanishes around the end of the G2 stage. These two facts together indicate that the G2 cycle is controlled by Cdkcs formed with cyclin A.

Similarly, cyclin E controls the transition from G1 to S.

These examples show how complex interactions among the different kinds of molecules in the cell cause distinct cycles of activities.