When does synapsis occur in meiosis?

Options

A. Zygotene
B. Leptotene
C. Diplotene
D. Pachytene

Answer

### Step-by-Step Solution:

1. **Understanding Meiosis**: Meiosis is a type of cell division that reduces the chromosome number by half, resulting in the formation of gametes (sperm and eggs). It consists of two successive divisions: Meiosis I and Meiosis II.

2. **Phases of Meiosis**: Meiosis I is further divided into several stages, including Prophase I, which is the longest phase of meiosis and consists of five sub-stages: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis.

3. **Identifying Synapsis**: Synapsis is the process where homologous chromosomes pair up during meiosis. This pairing is crucial for the exchange of genetic material and is a key step in genetic diversity.

4. **Locating Synapsis in the Phases**:
- **Leptotene**: The chromosomes start to condense and become visible, but synapsis does not occur here.
- **Zygotene**: This is the stage where synapsis occurs. Homologous chromosomes align closely together, forming pairs called bivalents.
- **Pachytene**: This stage follows Zygotene and is characterized by crossing over, where genetic material is exchanged between homologous chromosomes.
- **Diplotene**: In this stage, homologous chromosomes begin to separate but remain connected at points called chiasmata where crossing over has occurred.
- **Diakinesis**: This is the final stage of Prophase I, where the chromosomes condense further and the nuclear envelope breaks down.

5. **Conclusion**: Therefore, synapsis occurs during the Zygotene stage of Meiosis I.

### Final Answer:
**Synapsis occurs during the Zygotene stage of Meiosis I.**

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