________ phase synthesizes enzymes required during S phase.

Options

A. `G_(2)`
B. M
C. S
D. `G_(1)`

Answer

**Step-by-Step Solution:**

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

2. **Identifying the S Phase**: The S phase (Synthesis phase) is the part of interphase where DNA replication occurs. During this phase, the cell synthesizes a complete copy of the DNA in its nucleus.

3. **Role of Enzymes in DNA Replication**: DNA replication requires several enzymes, such as DNA polymerases, helicases, and ligases. These enzymes are primarily proteins that facilitate the replication process.

4. **Protein Synthesis Timing**: The question asks during which phase the enzymes required for the S phase are synthesized. It is important to note that proteins (including enzymes) are synthesized during specific phases of the cell cycle.

5. **Focus on G1 Phase**: The G1 phase (Gap 1 phase) is the first sub-phase of interphase. During this phase, the cell is actively growing and synthesizing various proteins, including those that will be needed for DNA replication in the S phase.

6. **Conclusion**: Since the enzymes required for DNA replication during the S phase are synthesized during the G1 phase, the answer to the question is "G1 Phase".

**Final Answer**: G1 Phase

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