CELL DIVISION
THE CELL CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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G1 Checkpoint
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G2 Checkpoint
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M Checkpoint
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I Checkpoint
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Detailed explanation-1: -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-2: -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.
Detailed explanation-3: -During G1 the cell increases in size and ensures it has all the machinery ready for DNA replication. The G1 check is a checkpoint where the cell must be large enough and have the machinery ready for DNA replication in the S phase.
Detailed explanation-4: -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. If the damage is irreparable, checkpoint signaling might activate pathways that lead to apoptosis.