The number of DNA in chromosome at `G_(2)` stage of cell cycle

Options

A. One
B. Two
C. Four
D. Eight

Answer

To determine the number of DNA molecules in a chromosome at the G2 stage of the cell cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Cell Cycle Phases**: The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).

2. **Identify the Starting Point**: At the beginning of the cell cycle, during the G1 phase, each chromosome contains one DNA molecule.

3. **DNA Replication in S Phase**: During the S phase, DNA replication occurs. This means that each chromosome is duplicated, resulting in two identical DNA molecules for each chromosome.

4. **Transition to G2 Phase**: After DNA replication in the S phase, the cell enters the G2 phase. Importantly, during the G2 phase, there is no further replication of DNA. Therefore, the number of DNA molecules remains the same as at the end of the S phase.

5. **Conclusion**: Since each chromosome has been duplicated during the S phase, by the time the cell reaches the G2 phase, each chromosome contains two DNA molecules.

Thus, the number of DNA in a chromosome at the G2 stage of the cell cycle is **2**.

### Final Answer: 2

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