The association of histone H1 with a nucleosome indicattes

Options

A. Transcription is occurring
B. DNA replication is occurring
C. The DNA is condensed into a chromatin fibre.
D. The DNA double helix is exposed.

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Nucleosome Structure**: A nucleosome is the fundamental unit of chromatin, consisting of a segment of DNA wrapped around a core of histone proteins. The core is made up of an octamer of histones, specifically two copies each of histones H2A, H2B, H3, and H4.

2. **Role of Histone H1**: Histone H1 is a linker histone that binds to the nucleosome. It is not part of the core octamer but instead associates with the DNA as it enters and exits the nucleosome. This association helps in the further compaction of the chromatin structure.

3. **Function of Histone H1**: The primary function of histone H1 is to facilitate the condensation of DNA into a more compact structure. This is crucial for the organization of DNA within the nucleus and plays a significant role in the formation of higher-order chromatin structures.

4. **Evaluating the Options**: The question asks what the association of histone H1 with a nucleosome indicates. The options provided include:
- A) Transcription
- B) DNA replication
- C) Condensation of DNA into chromatin fiber
- D) Exposure of the DNA double helix

Among these, the correct answer is C, as the presence of histone H1 indicates that the DNA is being condensed into a chromatin fiber.

5. **Conclusion**: Therefore, the association of histone H1 with a nucleosome indicates the condensation of DNA into chromatin fiber, which is essential for DNA organization and regulation within the cell.