Multiple Choice
Often, Cdks have to be dephosphorylated to become activated.
16. Cell Division
Control of the Cell Cycle
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Which of the following cell cycle checkpoints occurs immediately before the start of S phase?
A
G1
B
S
C
M
Verified step by step guidance1
Understand the cell cycle phases: The cell cycle consists of four main phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).
Identify the role of each phase: G1 is the phase where the cell grows and prepares for DNA replication. S phase is where DNA replication occurs. G2 is the phase where the cell prepares for mitosis, and M phase is where mitosis and cytokinesis occur.
Learn about cell cycle checkpoints: Checkpoints are control mechanisms that ensure the proper progression of the cell cycle. The main checkpoints are G1/S, G2/M, and the spindle checkpoint during mitosis.
Determine the location of the G1/S checkpoint: The G1/S checkpoint occurs at the end of the G1 phase, just before the cell enters the S phase. It ensures that the cell is ready for DNA replication.
Conclude which checkpoint occurs before S phase: Since the G1/S checkpoint is located at the end of G1 and before the start of S phase, it is the checkpoint that occurs immediately before the S phase.
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