AP BIOLOGY

Detailed explanation-1: -As at the G1 checkpoint, cell size and protein reserves are assessed. However, the most important role of the G2 checkpoint is to ensure that all of the chromosomes have been replicated and that the replicated DNA is not damaged.

Detailed explanation-2: -G2 checkpoint – DNA quality control After the second growth phase, the cell checks that the DNA was completely and correctly replicated during the S phase. If it passes it enters the M phase, and if it fails it tries to correct the errors. If the cell is unable to repair the DNA, it undergoes apoptosis.

Detailed explanation-3: -Loss of this function causes an identity crisis allowing G2 phase to overlap with S phase, leading to incomplete replication, an early mitosis, and subsequent DNA damage. Because the ATR-FOXM1 pathway ensures that G2 events are dependent on the completion of S phase, we refer to this as an intrinsic S/G2 checkpoint.

Detailed explanation-4: -The G2 checkpoint prevents cells from entering mitosis when DNA is damaged, providing an opportunity for repair and stopping the proliferation of damaged cells. Because the G2 checkpoint helps to maintain genomic stability, it is an important focus in understanding the molecular causes of cancer.

Detailed explanation-5: -These regulatory pathways are termed cell-cycle checkpoints. The G2/M checkpoint prevents cells from entering mitosis when DNA is damaged in order to afford these cells an opportunity to repair the damaged DNA before propagating genetic defects to the daughter cells.