NEET BIOLOGY

Detailed explanation-1: -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-2: -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-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: -The G1/S checkpoint prevents cells from replicating damaged DNA, whereas the G2/M checkpoint prevents cells from dividing with damaged DNA [18].

Detailed explanation-5: -Before the cell enters the G1 phase of the interphase, it goes through the Exit M checkpoint. Here the cell is checked to ensure that it has completed the mitosis phase and is ready for the first growth phase.