Join thousands of students who trust us to help them ace their exams!Watch the first video
Multiple Choice
Which of the following correctly identifies a cell-cycle checkpoint and a criterion required for a cell to pass it?
A
S checkpoint: Spindle fibers must be attached to kinetochores.
B
M checkpoint: Cell size must double before DNA replication begins.
C
G1 checkpoint: DNA must be undamaged before the cell commits to division.
D
G2 checkpoint: Chromosomes must be aligned at the metaphase plate.
Verified step by step guidance
1
Step 1: Understand the concept of cell-cycle checkpoints. These are control mechanisms in the cell cycle that ensure the accuracy of cell division. They prevent the progression of the cycle if certain conditions are not met.
Step 2: Review the major checkpoints in the cell cycle: G1 checkpoint, G2 checkpoint, S checkpoint, and M checkpoint. Each checkpoint has specific criteria that must be satisfied for the cell to proceed to the next phase.
Step 3: Analyze the G1 checkpoint. This checkpoint ensures that the cell's DNA is undamaged before committing to division. If the DNA is damaged, the cell will halt the cycle to repair the damage or undergo apoptosis (programmed cell death).
Step 4: Evaluate the G2 checkpoint. This checkpoint ensures that DNA replication is complete and accurate, and that the cell is ready for mitosis. Chromosomes do not align at the metaphase plate during this checkpoint; that occurs during the M checkpoint.
Step 5: Clarify the M checkpoint. This checkpoint ensures that spindle fibers are properly attached to kinetochores and that chromosomes are aligned at the metaphase plate before the cell proceeds to anaphase. This ensures proper chromosome segregation.