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Multiple Choice
At which stages of the cell cycle do the major regulatory checkpoints occur?
A
G1 and G2 phases
B
S phase and M phase
C
M phase and G0 phase
D
G0 phase and S phase
Verified step by step guidance
1
Understand the cell cycle: The cell cycle is divided into several phases, including G1, S, G2, and M phases. Each phase has specific functions and checkpoints that regulate the progression of the cycle.
Identify the G1 checkpoint: The G1 checkpoint occurs before the cell enters the S phase. It ensures that the cell is ready for DNA synthesis and checks for DNA damage, cell size, and nutrient availability.
Identify the G2 checkpoint: The G2 checkpoint occurs before the cell enters mitosis (M phase). It ensures that DNA replication is complete and checks for DNA damage, allowing the cell to repair any issues before proceeding.
Consider the S phase: Although not a major checkpoint, the S phase involves DNA replication. The cell ensures that replication is proceeding correctly, but the major checkpoints are in G1 and G2.
Consider the M phase: The M phase includes the mitotic checkpoint, which ensures that all chromosomes are properly attached to the spindle apparatus before the cell divides. This is crucial for accurate chromosome segregation.