AP BIOLOGY

Detailed explanation-1: -To make sure that cell division goes smoothly (produces healthy daughter cells with complete, undamaged DNA), the cell has an additional checkpoint before M phase, called the G 2start subscript, 2, end subscript checkpoint. At this stage, the cell will check: DNA integrity.

Detailed explanation-2: -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-3: -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-4: -The presence of hysteresis allows for M phase entry to be highly regulated as a function of cyclinB-Cdk1 activity. The mechanisms by which mitotic entry is prevented in response to DNA damage are similar to those in the G1/S checkpoint.