Which of the following does not undergo transcription of its genes?

Options

A. Barr bodies
B. Polytene chromosome
C. Euchromatin
D. Chromosome puff

Answer

To solve the question "Which of the following does not undergo transcription of its genes?" we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Transcription**:
- Transcription is the process where the DNA sequence of a gene is copied into RNA. This is the first step of gene expression and requires the enzyme RNA polymerase.

2. **Analyzing the Options**:
- **Option 1: Barr Bodies**:
- Barr bodies are the inactivated X chromosomes found in females. Since they are inactivated, they do not undergo transcription.
- **Conclusion**: Barr bodies do not participate in transcription.

- **Option 2: Polytene Chromosomes**:
- Polytene chromosomes are large chromosomes that are formed by the replication of DNA without cell division. They are found in certain tissues, such as salivary glands, and are known to participate in transcription.
- **Conclusion**: Polytene chromosomes do undergo transcription.

- **Option 3: Euchromatin**:
- Euchromatin is a form of chromatin that is less densely packed and is actively involved in transcription. It constitutes a significant portion of the genome and is accessible for transcription.
- **Conclusion**: Euchromatin participates in transcription.

- **Option 4: Chromosome Puff**:
- Chromosome puffs are localized swellings on polytene chromosomes that indicate regions of active transcription. They are sites where transcription is occurring.
- **Conclusion**: Chromosome puffs also undergo transcription.

3. **Final Conclusion**:
- After analyzing all the options, we find that the only option that does not undergo transcription is **Barr Bodies**.

### Answer:
**Barr Bodies do not undergo transcription of their genes.**

---