Biology / Unit 4 Bio 0879 short lesson, about 20 seconds
The G1 Checkpoint
Captions available
The idea
The G1 checkpoint is where a cell irreversibly commits to division, checking cell size, energy reserves, and DNA damage before allowing entry into S phase.
In practice
A cell failing the G1 checkpoint's damage check can pause to repair it or exit into quiescent G0.
Where people slip
Passing the G1 checkpoint is irreversible — a cell does not reverse course once past this gate.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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