AP BIOLOGY

Detailed explanation-1: -If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will D. complete the cycle and divide. G1 checkpoint occurs between the G1 and S phase of the cell cycle. When the cell is grown sufficiently and produces all components of DNA replication it enters in the S phase.

Detailed explanation-2: -o If the cell receives a go-ahead signal at the G1 checkpoint, it usually completes the cell cycle and divides.

Detailed explanation-3: -Once the cell passes the G1 checkpoint, the cell becomes committed to the cell cycle and enters the S phase where DNA is replicated. The checkpoint is to ensure the cell has grown enough and has enough resources to begin DNA replication.

Detailed explanation-4: -For a typical rapidly proliferating human cell with a total cycle time of 24 hours, the G1 phase might last about 11 hours, S phase about 8 hours, G2 about 4 hours, and M about 1 hour. Other types of cells, however, can divide much more rapidly.

Detailed explanation-5: -G1 (restriction) checkpoint. The G1 checkpoint, also known as the restriction point in mammalian cells and the start point in yeast, is the point at which the cell becomes committed to entering the cell cycle.