Final answer:
The G1 checkpoint, also known as the restriction point, is the cell cycle phase at which the cell commits to division, ensuring that only healthy and fully prepared cells proceed to DNA replication and eventual cell division.
Step-by-step explanation:
The checkpoint that commits a cell to division is the G1 checkpoint, also referred to as the restriction point. Passage through this checkpoint signifies that the cell has irreversibly committed to the cell division process. Conditions such as growth factors, cell size, nutrient status, and integrity of the DNA are assessed at this checkpoint. If these conditions are met, the cell moves forward into the S phase of the cell cycle. Otherwise, it may enter a quiescent state known as G0 or attempt to repair any detected damage before proceeding.
Regulation at this checkpoint is crucial to ensure that each daughter cell is an exact replica of the parent cell, preventing mutations from proliferating through more generations of cells. The G1 checkpoint is one of several checkpoints in the eukaryotic cell cycle, but it is the one that primarily determines whether a cell commits to complete the rest of the division cycle.