The beginning of which stage of prophase is marked by complete terminalisation of chiasmata and inhibition of RNA synthesis ?

Options

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

Answer

To solve the question regarding the stage of prophase marked by complete terminalization of chiasmata and inhibition of RNA synthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the stages of Prophase I**: Prophase I of meiosis consists of several stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. Each stage has distinct characteristics and events.

2. **Identify the key events**: The question mentions two key events:
- Complete terminalization of chiasmata
- Inhibition of RNA synthesis

3. **Analyze the stages**:
- **Leptotene**: Chromosomes start to condense, but no chiasmata are formed.
- **Zygotene**: Homologous chromosomes begin to pair and form synapses, but chiasmata are not yet terminalized.
- **Pachytene**: Crossing over occurs, leading to the formation of chiasmata, but they are not yet terminalized.
- **Diplotene**: Chiasmata become visible, and homologous chromosomes begin to separate, but they are still not fully terminalized.
- **Diakinesis**: This is the final stage of prophase I where chiasmata are completely terminalized, and RNA synthesis is inhibited.

4. **Conclude the answer**: Based on the analysis, the stage of prophase that is marked by complete terminalization of chiasmata and inhibition of RNA synthesis is **Diakinesis**.

### Final Answer:
The beginning of the stage of prophase marked by complete terminalization of chiasmata and inhibition of RNA synthesis is **Diakinesis**.

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