AP BIOLOGY

Detailed explanation-1: -This checkpoint, also called the restriction checkpoint, takes place between the G1 and the S phase. The cell verifies that it is large enough to divide, that its DNA is intact, and if there is enough access to nutrients and stimulating growth factors.

Detailed explanation-2: -G2/M checkpoints include the checks for damaged DNA, unreplicated DNA, and checks that ensure that the genome is replicated once and only once per cell cycle. If cells pass these checkpoints, they follow normal transition to the M phase.

Detailed explanation-3: -The G1 checkpoint determines whether all conditions are favorable for cell division to proceed. The G1 checkpoint, also called the restriction point (in yeast), is a point at which the cell irreversibly commits to the cell division process.

Detailed explanation-4: -For example, the G1 checkpoint ensures that the size of the cell is large enough to progress into the S phase and checks for the presence of DNA damage [26].