DNA duplication occurs in:

Options

A. mitosis only
B. meiosis only
C. meiosis I and mitosis
D. meiosis II and mitosis

Answer

**Step-by-Step Solution:**

1. **Understanding DNA Duplication**: DNA duplication, also known as DNA replication, is the process by which a cell makes an exact copy of its DNA. This is crucial for cell division, as each daughter cell needs to receive a complete set of DNA.

2. **Identifying the Cell Cycle Stages**: The cell cycle consists of several stages: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis). DNA duplication specifically occurs during the S phase of the cell cycle.

3. **Role of DNA Duplication in Mitosis**: In mitosis, DNA duplication is essential because it ensures that when a cell divides, each daughter cell receives an identical set of chromosomes. This duplication occurs before the cell enters mitosis.

4. **Role of DNA Duplication in Meiosis**: Meiosis is a type of cell division that reduces the chromosome number by half and is essential for sexual reproduction. DNA duplication also occurs before meiosis begins, specifically during the S phase.

5. **Meiosis I and Meiosis II**: Meiosis consists of two stages: Meiosis I and Meiosis II. During Meiosis I, homologous chromosomes are separated into two daughter cells, and during Meiosis II, the sister chromatids are separated. The actual DNA duplication occurs before these stages, during the S phase.

6. **Conclusion**: Therefore, DNA duplication occurs during the S phase of the cell cycle, which is prior to both mitosis and meiosis I. The correct answer to the question is that DNA duplication occurs in both mitosis and meiosis I.

**Final Answer**: DNA duplication occurs in mitosis and meiosis I.

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