DNA synthesis takes place in :-

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the phase in which DNA synthesis occurs during the cell cycle.

2. **Identifying the Phases of Interphase**: The cell cycle consists of several phases, and interphase is divided into three main parts:
- G1 Phase (Gap 1)
- S Phase (Synthesis)
- G2 Phase (Gap 2)

3. **Analyzing Each Phase**:
- **G1 Phase**: This phase is characterized by cell growth and metabolic activity. During G1, the cell prepares for DNA replication, but DNA synthesis does not occur here.
- **S Phase**: This is the critical phase where DNA replication takes place. The term "S" stands for synthesis, indicating that this is when the DNA is synthesized.
- **G2 Phase**: In this phase, the cell continues to grow and prepares for mitosis. It synthesizes proteins and enzymes necessary for cell division, but no DNA synthesis occurs here.

4. **Evaluating the Options**:
- **Option 1 (S Phase)**: This is the correct answer as DNA synthesis occurs during this phase.
- **Option 2 (G1 Phase)**: This option is incorrect because DNA synthesis does not occur here.
- **Option 3 (G2 Phase)**: This option is also incorrect as G2 is focused on preparation for mitosis, not DNA synthesis.
- **Option 4 (NONE)**: This option is incorrect since DNA synthesis does indeed occur in the S phase.

5. **Conclusion**: The correct answer to the question "DNA synthesis takes place in:" is **Option 1 (S Phase)**.

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