The enzyme recombinase is required in which stage of meiosis ?

Options

A. Formation of synaptonemal complex
B. Crossing over between nonsister chromatids
C. Condensation of chromosomes
D. Alignment of bivalent chromosomes on equatorial plate.

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Recombinase:**
- The enzyme recombinase is crucial for the process of recombination, which involves the exchange of genetic material between non-sister chromatids.

2. **Identifying the Process of Recombination:**
- Recombination occurs during crossing over, which specifically takes place in meiosis. This process is essential for genetic diversity.

3. **Locating the Stage of Meiosis:**
- In meiosis, crossing over occurs during prophase I. This is when homologous chromosomes pair up and exchange segments.

4. **Focusing on the Specific Stage:**
- Prophase I is divided into several stages, and the actual crossing over (where recombination occurs) happens during the pachytene stage of prophase I.

5. **Evaluating the Options Given:**
- The options provided include:
- Formation of synaptonemal complex (occurs in diplotene)
- Crossing over between non-sister chromatids (occurs in pachytene)
- Condensation of chromosomes (occurs at the onset of prophase)
- Alignment of bivalent chromosomes on the equatorial plate (occurs during metaphase)
- Among these, the option that directly relates to the function of recombinase is the second one: crossing over between non-sister chromatids.

6. **Conclusion:**
- Therefore, the enzyme recombinase is required during the pachytene stage of prophase I in meiosis.

**Final Answer:** The enzyme recombinase is required during the pachytene stage of prophase I in meiosis.

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