Cell Cycle: The Importance of Cellular Checkpoints
Which checkpoint is responsible for checking a cell with damaged DNA?
A: M checkpoint
B: G2 checkpoint
C: G1 checkpoint
Answer:
The checkpoint responsible for checking a cell with damaged DNA is G1 checkpoint.
Cell cycle checkpoints are crucial mechanisms that control the progression of a cell through its various stages. These checkpoints ensure that each step in the cell cycle is completed accurately before the next step begins. One of the key functions of these checkpoints is to monitor the integrity of the DNA within the cell.
There are three main checkpoints in the cell cycle: G1 checkpoint, G2 checkpoint, and the spindle checkpoint. Each of these checkpoints plays a specific role in ensuring the proper division of the cell.
G1 Checkpoint:
The G1 checkpoint is the first decision point in the cell cycle. At this checkpoint, the cell evaluates the integrity of its DNA and assesses external factors that may impact cell division. If the conditions are not favorable or if the DNA is damaged, the cell will not proceed to the S phase where DNA replication occurs.
G2 Checkpoint:
The G2 checkpoint occurs towards the end of the interphase, before the cell enters mitosis. This checkpoint ensures that all the chromosomes have been replicated accurately and that the replicated DNA is intact and undamaged.
M Checkpoint:
The M checkpoint, also known as the spindle checkpoint, monitors the attachment of sister chromatids to the spindle apparatus. This checkpoint ensures that each daughter cell receives the correct number of chromosomes during cell division.
In conclusion, the cell cycle checkpoints, particularly the G1 checkpoint, play a crucial role in maintaining the integrity of the cell's DNA. These checkpoints act as guardians, preventing cells with damaged DNA from dividing and potentially passing on genetic abnormalities. Understanding the function of these checkpoints is essential in studying cell cycle regulation and the mechanisms that govern normal cellular proliferation.