Which one of the following is NOT a major checkpoint in the cell division cycle of eukaryotic cell?
Which one of the following is NOT a major checkpoint in the cell division cycle of eukaryotic cell?
Select an option to attempt
Correct Answer: Option B
Explanation
Major cell cycle checkpoints in eukaryotes:The three major checkpoints:1. G1/S checkpoint (Restriction point in G1): Checks for DNA damage, adequate cell size, and growth factor signals before committing to DNA replication. Key proteins: p53, Rb, CDK4/6-cyclin D.2. G2/M checkpoint: Ensures all DNA has been replicated correctly and any damage is repaired before mitosis. Key proteins: CDK1-cyclin B (MPF), ATM/ATR.3. Spindle Assembly Checkpoint (SAC, M phase): Ensures all kinetochores are properly attached to spindle microtubules before anaphase. Key proteins: Mad2, BubR1.The S-to-G2 transition is NOT a recognised major checkpoint in the classical cell cycle model.Answer: G1/S, G2/M, and Spindle Assembly Checkpoint (metaphase→anaphase) are the three major checkpoints.