A typical nuclesome in a DNA helix contains:

Options

A. 290 bp
B. 200 bp
C. 300 bp
D. 400 bp

Explanation

To solve the question regarding how many base pairs are contained in a typical nucleosome in a DNA helix, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nucleosomes**: A nucleosome is a structural unit of DNA, consisting of a segment of DNA wrapped around a core of histone proteins. This structure helps in the packaging of DNA into a compact form.

2. **Identifying the Components**: Each nucleosome consists of about 146 base pairs of DNA that are wrapped around a histone octamer, which is made up of eight histone proteins.

3. **Calculating Total Base Pairs**: In addition to the 146 base pairs that are tightly wrapped around the histone octamer, there is also a linker DNA that connects adjacent nucleosomes. The total length of DNA associated with a nucleosome (including the linker) is approximately 200 base pairs.

4. **Choosing the Correct Answer**: Given the options provided:
- A) 290
- B) 200
- C) 300
- D) 400

The correct answer is B) 200 base pairs, as this is the typical amount of DNA associated with a nucleosome.

### Final Answer:
A typical nucleosome in a DNA helix contains approximately **200 base pairs**.

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