Which of the following stage of meiosis the enzyme recombinase is required?

Options

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

Answer

To determine which stage of meiosis requires the enzyme recombinase, we will analyze each of the given options: pachytene, zygotene, diplotene, and diakinesis.

### Step-by-Step Solution:

1. **Understanding Meiosis Stages**:
- Meiosis consists of two main divisions: meiosis I and meiosis II, and it includes several stages: prophase, metaphase, anaphase, and telophase. Prophase I is further divided into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

2. **Identifying the Role of Recombinase**:
- Recombinase is an enzyme that facilitates genetic recombination, which is essential for crossing over between homologous chromosomes.

3. **Analyzing Each Option**:
- **Zygotene**: In this stage, homologous chromosomes begin to pair up (synapsis), but crossing over has not yet occurred. Therefore, recombinase is not required here.
- **Pachytene**: This is the stage where crossing over occurs. Recombinase is actively involved in facilitating the exchange of genetic material between homologous non-sister chromosomes. Thus, recombinase is required in this stage.
- **Diplotene**: During this stage, the homologous chromosomes begin to separate, and while some crossing over may have occurred, the primary activity of recombinase is not required here.
- **Diakinesis**: This is the final stage of prophase I where the chromosomes condense further and prepare for metaphase. Recombinase is not required in this stage as the crossing over has already occurred.

4. **Conclusion**:
- The stage of meiosis where the enzyme recombinase is required is **pachytene**.

### Final Answer:
**Pachytene**