What happens if a cell does not pass the G1 checkppoint?

If a cell does not pass the G1 checkpoint, it is typically directed to enter a resting state known as the G0 phase, where it can remain metabolically active but not divide. This checkpoint assesses factors such as DNA integrity, cell size, and nutrient availability to ensure that the cell is ready for DNA replication. If the cell has irreparable damage or unfavorable conditions, it may undergo apoptosis, or programmed cell death, to prevent potentially harmful mutations from being passed on.