AP BIOLOGY

Detailed explanation-1: -Cell cycle checkpoints are surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis.

Detailed explanation-2: -At the G2 checkpoint, the cell checks for: DNA damage. DNA replication completeness.

Detailed explanation-3: -The integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint.

Detailed explanation-4: -G1 checkpoint – size and nutrient verification 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. If it passes the G1 checkpoint, it irreversibly commits to complete the whole cell cycle and divide.

Detailed explanation-5: -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.