Question

Which of the following factors might cause a cell to pause in a phase of the cell cycle?

A) DNA replication
B) Presence of growth factors
C) DNA damage
D) Completion of cytokinesis

Answer 1

DNA damage can cause a cell to pause in the cell cycle, particularly at the G1 checkpoint where the cell decides if it's ready for DNA replication. Sample B's doubled DNA content suggests it's in the G2 phase after successful DNA replication.

Step-by-step explanation:

Among the factors that might cause a cell to pause in a phase of the cell cycle, DNA damage is a significant one. In response to DNA damage, a cell will activate checkpoint mechanisms, particularly at the G1 and G2 phases, to prevent progression until the damage is repaired.

For example, at the G1 checkpoint, the cell assesses whether it is ready for DNA replication during the S phase of interphase. If the cell detects DNA damage, it halts the cycle, attempting to repair the DNA before proceeding. Regarding sample B from the provided scenario, as the DNA content of the cells has doubled, it indicates that DNA replication has successfully occurred, and the cells are most likely in the G2 phase of interphase, just prior to mitosis.