Final answer:
The G1 checkpoint checks for damaged DNA and unfavorable conditions before a cell can proceed to the S phase of cell division. The G2 checkpoint verifies that DNA replication is complete and DNA is undamaged before mitosis. The M checkpoint oversees proper chromosome separation.
Step-by-step explanation:
In the G1 checkpoint, unfavorable extracellular environment and damaged DNA is checked. The G1 checkpoint, also known as the restriction point, is crucial for ensuring that all conditions are favorable for cell division to proceed. If a cell’s DNA is damaged, the checkpoint mechanisms will prevent the cell from entering the S phase and the cell will attempt to repair the damaged genomic DNA. Similarly, the G2 checkpoint ensures that all chromosomes have been replicated and that the replicated DNA is not damaged before the cell enters mitosis. Whereas the M checkpoint is concerned with the proper attachment of the spindle to the kinetochore and proper separation of sister chromatids during mitosis.