Question

Cell division cannot be stopped in which phase of the cell cycle?

• A. G$1$-phase
• B. G$2$-phase
• C. S-phase
• D. Prophase

Answer 1

The correct option is C S-phase

The interphase comprises of G${}_1$, S and G${}_2$ phase. In G${}_1$ phase the a cell has three options:

(a) Continue cell cycle and enter S phase,

(b) Stop cell cycle and enter quiescent stage or G${}_0$ phase

(c) Stop cell cycle and undergo differentiation.

The S phase is known as synthetic phase, in which DNA undergoes replication. As the DNA has replicates in S phase, the DNA content has become two times the normal content. The S phase must necessarily follow the S phase. Thus, the S phase is point of no return for a cell cycle and the cell must divide in the M phase of the cell cycle.