Synthesis of DNA takes place in
(a) `G_(2)`
(b) `G_(1)`
(c) S
(d) None of these

Options

A. `G_(2)`
B. `G_(1)`
C. S
D. None of these

Answer

To determine in which phase the synthesis of DNA takes place, let's analyze the options provided:

1. **Understanding the Cell Cycle**: The cell cycle consists of two main phases: interphase and the mitotic phase (M phase). Interphase is further divided into three phases: G1, S, and G2.

2. **Analyzing Each Phase**:
- **G1 Phase (Gap 1)**: This is the first phase of interphase where the cell grows and synthesizes various enzymes and proteins. However, DNA synthesis does not occur in this phase.
- **S Phase (Synthesis)**: This is the phase where DNA synthesis occurs. During this phase, the cell duplicates its DNA, resulting in two copies of each chromosome. If the cell starts with 2C (amount of DNA), after the S phase, it will have 4C.
- **G2 Phase (Gap 2)**: This is the final phase of interphase where the cell prepares for mitosis. It involves further growth and the synthesis of proteins necessary for cell division, but no DNA synthesis occurs here.

3. **Conclusion**: Based on the analysis, the synthesis of DNA takes place specifically in the S phase.

Therefore, the correct answer is **(c) S**.