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Why cyclin degradation is important?

Option: 1

To exit from mitosis

Option: 2

It permits fresh DNA replication to take place.

Option: 3

To enter in mitosis

Option: 4

Both a and b

Answers (1)


D. The breakdown of cyclins is required for mitosis to end. The progression of cells through mitosis depends on the proteins cyclin B1 and cyclin-dependent kinase 1 (CDK1). The active CDK1/cyclin B1 complex is created during mitosis when cyclin B1 binds to CDK1. When cyclin B1 degrades at the end of mitosis, CDK1 is rendered inactive, enabling the cell to exit the cell cycle. In order to begin a fresh cycle of DNA replication, cyclins must be degraded. The cyclin-dependent kinase 2 (CDK2) and cyclin E complex, which is active throughout the G1 phase of the cell cycle, phosphorylates and activates the proteins required for DNA replication. When cyclin E degrades at the end of the G1 phase, CDK2 is inactivated, halting DNA replication until the cell enters the subsequent phase of the cell cycle. Hence option D is correct.

Cell division takes place during the cell cycle phase known as mitosis. Cyclin degradation is required for the escape from mitosis, not the entry into it. Hence option C is incorrect.

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Ritika Kankaria

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