Number of nucleosomes found in helical coil of 30nm chromatin fiber is

Options

A. 6
B. 10
C. 12
D. 15

Answer

To determine the number of nucleosomes found in a helical coil of 30 nm chromatin fiber, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nucleosomes**:
- Nucleosomes are the basic units of DNA packaging in eukaryotic cells. Each nucleosome consists of a segment of DNA wrapped around a core of histone proteins.

2. **Structure of Chromatin**:
- Chromatin fibers can exist in different forms, with the 30 nm fiber being a more compact structure. The 30 nm chromatin fiber is formed by the coiling of nucleosomes.

3. **Nucleosome Composition**:
- Each nucleosome contains approximately 146 base pairs of DNA wrapped around a histone octamer (eight histone proteins).

4. **Nucleosome Density in 30 nm Fiber**:
- In a 30 nm chromatin fiber, nucleosomes are arranged in a way that allows for a specific number of nucleosomes per unit length. Typically, there are about 6 nucleosomes per 30 nm of chromatin fiber.

5. **Conclusion**:
- Therefore, the number of nucleosomes found in a helical coil of 30 nm chromatin fiber is **6**.

### Final Answer:
The number of nucleosomes in a helical coil of 30 nm chromatin fiber is **6**.

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