In B-DNA, the rise per base pair would be

Options

A. `4.3 Å`
B. `2.4 Å`
C. `3.4 Å`
D. `4.2 Å`

Answer

To solve the question regarding the rise per base pair in B-DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of DNA**:
- DNA can exist in different forms, namely A-DNA, B-DNA, and Z-DNA. Among these, B-DNA is the most common form found in nature.

2. **Identify the Characteristics of B-DNA**:
- B-DNA is a right-handed helical structure. This means that it twists in a clockwise direction.

3. **Define 'Rise per Base Pair'**:
- The term "rise per base pair" refers to the vertical distance between two adjacent base pairs in the DNA helix.

4. **Know the Measurement**:
- In B-DNA, the distance (or rise) between two base pairs is approximately 0.34 nanometers.

5. **Convert Units**:
- Convert 0.34 nanometers to angstroms. Since 1 nanometer equals 10 angstroms, we can calculate:
\[ 0.34 \, \text{nanometers} = 0.34 \times 10 \, \text{angstroms} = 3.4 \, \text{angstroms} \]

6. **Select the Correct Option**:
- From the provided options (4.3 angstroms, 2.4 angstroms, 3.4 angstroms, 4.2 angstroms), the correct answer is 3.4 angstroms.

### Final Answer:
The rise per base pair in B-DNA is **3.4 angstroms**.

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