Which checkpoint ensures that genomic replication is complete and checks for DNA instability?

The G2/M checkpoint plays a critical role in the cell cycle by ensuring that DNA replication has been accurately completed and that the DNA is stable before the cell proceeds to mitosis. This checkpoint occurs after the synthesis phase (S phase), where DNA replication occurs, and before the cell enters mitosis (M phase).

At the G2/M checkpoint, several mechanisms are in place to detect any DNA damage or abnormalities that may have arisen during DNA replication. If any issues are detected, the cell can activate repair processes or, in some cases, initiate programmed cell death to prevent the proliferation of cells with genetic errors. This quality control mechanism helps maintain genomic integrity, which is vital for the proper functioning of cells and the organism as a whole.

In contrast, the G1/S checkpoint primarily assesses the cell's readiness for DNA replication and checks for any external signals or growth factors that could influence cell division. The M/G1 phase typically refers to the point after mitosis may be complete, transitioning into the first gap phase, while the S/G2 phase does not directly serve as a checkpoint for genomic stability and replication completion. Thus, the G2/M checkpoint is specifically tailored for the functions of ensuring successful DNA replication and maintaining genomic integrity.