How far is each base pair from the next one in the DNA double helix model?

Options

A. 2 nm
B. 3.4 nm
C. 34 nm
D. 0.34 nm

Answer

To determine the distance between each base pair in the DNA double helix model, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of DNA**:
- DNA is structured as a double helix, consisting of two strands that wrap around each other. Each strand is made up of nucleotide units, which include a sugar, a phosphate group, and a nitrogenous base.

2. **Identifying Base Pairs**:
- The nitrogenous bases pair specifically: Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). These pairs form the rungs of the helical ladder.

3. **Pitch of the Helix**:
- The term "pitch" refers to the length of one complete turn of the DNA helix. For DNA, the pitch is approximately 3.4 nanometers.

4. **Number of Base Pairs per Turn**:
- In one complete turn of the DNA helix, there are about 10 base pairs.

5. **Calculating the Distance Between Base Pairs**:
- To find the distance between two adjacent base pairs, we can divide the pitch by the number of base pairs per turn:
\[ \text{Distance between base pairs} = \frac{\text{Pitch}}{\text{Number of base pairs per turn}} = \frac{3.4 \text{ nm}}{10} = 0.34 \text{ nm} \]

6. **Conclusion**:
- Therefore, the distance between each base pair in the DNA double helix is 0.34 nanometers.

### Final Answer:
The distance between each base pair in the DNA double helix model is **0.34 nanometers**.

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