Synapsis (pairing of chromosomes) takes place in

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the stage of the cell cycle where synapsis, or the pairing of homologous chromosomes, occurs.

2. **Identifying the Stages**:
- **Leptotene**: This is the first stage of prophase I in meiosis where chromosomes begin to condense and become visible. However, synapsis does not occur in this stage.
- **Zygotene**: This is the second stage of prophase I where synapsis occurs. Homologous chromosomes pair up during this stage.
- **Pachytene**: This is the third stage of prophase I where crossing over occurs between non-sister chromatids. Synapsis has already taken place by this stage.
- **Diplotene**: This is the fourth stage of prophase I where the homologous chromosomes begin to separate, and synapsis ends.

3. **Analyzing Each Option**:
- **Option 1 (Leptotene)**: Incorrect, as synapsis does not occur here.
- **Option 2 (Zygotene)**: Correct, as this is the stage where synapsis occurs.
- **Option 3 (Pachytene)**: Incorrect, as synapsis has already occurred by this stage.
- **Option 4 (Diplotene)**: Incorrect, as synapsis ends in this stage.

4. **Conclusion**: The correct answer is **Zygotene**, where the pairing of homologous chromosomes (synapsis) takes place.

**Final Answer**: Synapsis (pairing of chromosomes) takes place in **Zygotene**.

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