Chapter 8, Problem 1BYB

Summary Introduction

To write:

Roles of checkpoints in the cell cycle.

Introduction:

Cell cycle is the sequence of events that take place during cell division. This is responsible for the growth and replication of the cells. Check points in the cell cycle are the control points at which the cycle is halted till the conditions are favourable for the cycle to continue.

Explanation of Solution

Checkpoints are the regulatory mechanisms of the cell cycle which are designed to ensure that internal, as well as, external environment are favourable for the cell cycle to progress. Hence, they play an important role in the cell cycle. They sense the defects which occur during crucial processes like DNA replication or chromosome segregation and halt the cell cycle till the defects are repaired.

There are numerous checkpoints in a cell cycle, but out of those, there are three most important check points which are G1 checkpoint or restriction checkpoint (where the cell checks if it should enter the cell cycle or not), G2 check point or M check point (where the cell checks for the integrity and replication of DNA), and metaphase checkpoint or spindle checkpoint (where the cell checks for the attachment of the chromosomes to the spindle at the metaphase plate after which the cell enters the irreversible anaphase where the chromosomes split and form daughter cells).

Conclusion

The daughter cells should be the exact duplicates of the parent cell, so that mutation can be avoided as it can be transferred to every new cell that is formed from the abnormal cell. To ensure this, the cells develop control mechanism known as checkpoints which control the cell cycle based on both internal as well as external environment of the cell.