AP BIOLOGY

Detailed explanation-1: -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-2: -These data indicate that the G1 checkpoint is activated in response to mitotic DNA damage in the presence of p53, and that the mitotic DNA damage response is connected to the G1 checkpoint by p53. If cells continue to possess damaged DNA, apoptosis is induced in a p53-dependent manner.

Detailed explanation-3: -1: Internal Checkpoints During the Cell Cycle: The cell cycle is controlled at three checkpoints. 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: -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.