Why is the G₁ checkpoint important in cell cycle regulation?

Question:

A cell has damaged DNA. Which checkpoint is responsible for checking this?

A. M checkpoint

B. G₂ checkpoint

C. G₁ checkpoint

Answer:

The correct answer is: C. G₁ checkpoint

The G₁ checkpoint is crucial in cell cycle regulation as it plays a vital role in monitoring the integrity of the cell's DNA before progressing to the next phase of the cell cycle. This checkpoint ensures that the cell's DNA is undamaged and capable of accurately replicating during the S phase.

During the G₁ phase of the cell cycle, the cell prepares for DNA synthesis and growth. At the G₁ checkpoint, the cell evaluates the DNA for any damage. If damaged DNA is detected, the checkpoint can activate repair mechanisms to fix the DNA. If the damage is too severe to be repaired, the checkpoint can also trigger apoptosis, or programmed cell death, to prevent the propagation of mutated or damaged DNA.

Overall, the G₁ checkpoint acts as a critical quality control point to ensure the proper functioning and integrity of the cell's DNA before moving forward in the cell cycle. Understanding the significance of the G₁ checkpoint is essential in studying cell cycle regulation and the maintenance of genomic stability.