Final answer:
Cell cycle checkpoints at the end of G1, the G2/M transition, and during metaphase ensure the cell division process is correct and prevent mutations from propagating. The G1 checkpoint assesses DNA integrity, the G2 checkpoint confirms proper chromosome duplication, and the metaphase checkpoint ensures correct chromosome alignment and attachment.
Step-by-step explanation:
Checkpoints in the cell cycle ensure the accuracy and integrity of cell division. These checkpoints are critical control mechanisms that prevent mutations and maintain the health of growing tissues by ensuring cells do not divide under unfavorable conditions. The three main checkpoints are:
- The G1 checkpoint, which assesses the integrity of DNA before the cell commits to entering the S phase of DNA synthesis.
- The G2 checkpoint, which ensures that chromosome duplication has occurred properly and the cell is ready for mitosis.
- The metaphase (M) checkpoint, which checks that all chromosomes are properly attached to spindle fibers and aligned at the metaphase plate before anaphase can proceed.
At each of these checkpoints, molecules like cyclin-dependent kinases (CDKs) act as signals to either halt cell cycle progression or allow it to continue, depending on the readiness of the cell to advance to the next stage.