B-DNA which is right -handed double helix contains ______ base pairs per turn of the helix and each tum is _____ long .

Options

A. 10, 3.4 Å
B. 10, 34 Å
C. 11, 20 Å
D. 11, 34 Å

Explanation

To answer the question regarding B-DNA, we need to identify two key pieces of information: the number of base pairs per turn of the helix and the length of each turn.

### Step-by-Step Solution:

1. **Understanding B-DNA Structure**:
- B-DNA is a right-handed double helix structure. This means that as you move along the helix, it twists in a clockwise direction.

2. **Base Pairs per Turn**:
- In B-DNA, there are **10 base pairs** present in each complete turn of the helix. This is a standard characteristic of B-DNA.

3. **Length of Each Turn**:
- The length of one complete turn of the helix is **34 angstroms**. This measurement indicates the distance that the helix covers in one full twist.

4. **Final Answer**:
- Therefore, B-DNA which is a right-handed double helix contains **10 base pairs per turn** of the helix, and each turn is **34 angstroms long**.

### Final Answer:
B-DNA which is right-handed double helix contains **10 base pairs** per turn of the helix and each turn is **34 angstroms long**.

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