What does the G1 checkpoint determine?

The G1 checkpoint is a critical regulatory point in the cell cycle that primarily assesses whether the cell is ready to progress to the next phase, specifically the synthesis (S) phase where DNA replication occurs. At this checkpoint, several factors are evaluated to determine if the conditions are favorable for the cell to divide.

One of the key considerations at the G1 checkpoint is the cell's size, the integrity of its DNA, and the availability of necessary growth factors and nutrients. If these criteria are met, the cell is deemed ready to proceed to division. Therefore, the G1 checkpoint plays a crucial role in ensuring that only healthy, sufficiently prepared cells continue through the cell cycle to division, helping maintain tissue integrity and function.

The other options focus on different aspects of cell function but do not encapsulate the primary role of the G1 checkpoint, which is centered around regulating the cell's readiness for division.