AP BIOLOGY

Detailed explanation-1: -There is adequate room in the environment for more cells. Which checkpoint appears to regulate whether the cell is in G0 or not? the G1 checkpoint is the point in the cycle where the cell goes into or out of G0.

Detailed explanation-2: -The G1 checkpoint. The G1 checkpoint is located at the end of G1 phase, before the transition to S phase. If cells don’t pass the G1 checkpoint, they may “loop out” of the cell cycle and into a resting state called G0, from which they may subsequently re-enter G1 under the appropriate conditions.

Detailed explanation-3: -G1 checkpoint – size and nutrient verification This checkpoint, also called the restriction checkpoint, takes place between the G1 and the S phase. 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.

Detailed explanation-4: -In order to proceed to the next phase of interphase, the cell must pass the G1 checkpoint. In order for this to happen, cyclin proteins must be present and the proper cellular conditions must occur. If the cell passes the checkpoint it will proceed to the S phase, during which DNA replication occurs.

Detailed explanation-5: -The G1/S cell cycle checkpoint controls the passage of eukaryotic cells from the first gap phase (G1) into the DNA synthesis phase (S). Two cell cycle kinases, CDK4/6-cyclin D and CDK2-cyclin E, and the transcription complex that includes Rb and E2F are pivotal in controlling this checkpoint.