During cell cycle, DNA replicates

Options

A. Once
B. Twice
C. Many times
D. Not at all

Answer

**Step-by-Step Solution:**

1. **Understanding the Cell Cycle**: The cell cycle is a series of events that a cell goes through as it grows and divides. It consists of four main phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).

2. **Identifying the Phases**:
- **G1 Phase**: This is the first gap phase where the cell grows and duplicates its contents (like RNA and proteins), but not its DNA.
- **S Phase**: This is the synthesis phase where DNA replication occurs. Each chromosome is duplicated to form two sister chromatids.
- **G2 Phase**: This is the second gap phase where the cell continues to grow and prepares for mitosis.
- **M Phase**: This is the mitotic phase where the cell divides into two identical daughter cells.

3. **Focus on DNA Replication**: The question specifically asks about DNA replication during the cell cycle. From the phases identified, we see that DNA replication only occurs during the S phase.

4. **Conclusion**: Therefore, DNA replicates only once during the cell cycle, specifically in the S phase.

5. **Final Answer**: The correct answer to the question is that DNA replicates once during the cell cycle.

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