Which of the following is the correct sequence ?

Options

A. Leptotene `to` Diakinesis `to` Diplotene `to` Zygotene `to` Pachytene
B. Diplotene `to` Leptotene `to` Zygotene `to` Pachytene `to` Diakinesis
C. Leptotene `to` Zygotene `to` Pachytene `to` Diplotene `to` Diakinesis
D. Diakinesis `to` Diplotene `to` Pachytene `to` Zygotene `to` Leptotene

Answer

To determine the correct sequence of the sub-stages of prophase I in meiosis, we need to understand the order of these stages. Prophase I is a crucial phase in meiosis that consists of five distinct sub-stages. Here’s the step-by-step breakdown of the correct sequence:

### Step-by-Step Solution:

1. **Identify the Stages of Prophase I**:
Prophase I is divided into five sub-stages:
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis

2. **Sequence the Stages**:
The correct order of these sub-stages is:
- **Leptotene**: This is the first stage where chromosomes start to condense and become visible.
- **Zygotene**: In this stage, homologous chromosomes begin to pair up (synapsis).
- **Pachytene**: This stage is characterized by the crossing over of genetic material between homologous chromosomes.
- **Diplotene**: Here, the homologous chromosomes begin to separate but remain attached at chiasmata.
- **Diakinesis**: This is the final stage of prophase I where the chromosomes condense further and the nuclear envelope breaks down, preparing for metaphase.

3. **Evaluate the Options**:
Given the options, we can eliminate those that do not follow the correct order:
- Any option that starts with Diplotene or Diakinesis is incorrect since they are not the first stages.
- The option that starts with Leptotene and follows the correct sequence through to Diakinesis is the correct one.

4. **Conclusion**:
The correct sequence is:
- **Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis**.

### Final Answer:
The correct sequence of the sub-stages of prophase I is **Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis**.

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