Protein synthesis occurs during

Options

A. S phase and `G_(1)` phase only
B. `G_(1), G_(2)` and S phase
C. `G_(1)` and M-phase only
D. S and `G_(2)` phase only

Answer

**Step-by-Step Solution:**

1. **Understanding the Cell Cycle**: The cell cycle consists of a series of phases that a cell goes through to prepare for division. It includes four main stages: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).

2. **Identifying the Phases**:
- **G1 Phase**: This is the first phase where the cell grows in size and synthesizes mRNA and proteins necessary for DNA synthesis.
- **S Phase**: In this phase, DNA replication occurs, and histone proteins (which help package DNA) are synthesized.
- **G2 Phase**: This phase involves further growth and preparation for cell division, during which additional proteins are synthesized.
- **M Phase**: This is the phase where actual cell division occurs, and protein synthesis does not take place.

3. **Analyzing Protein Synthesis**:
- Protein synthesis occurs in the G1 phase as the cell prepares for DNA replication.
- In the S phase, while DNA is being replicated, histone proteins are also synthesized.
- In the G2 phase, the cell continues to synthesize proteins as it prepares for mitosis.

4. **Conclusion**: Since protein synthesis occurs in G1, S, and G2 phases, the correct answer to the question "Protein synthesis occurs during" is "G1, G2, and S phase."

**Final Answer**: Protein synthesis occurs during G1, G2, and S phases of the cell cycle.

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