Question

The distance between adjacent nucleotides in DNA is:

• A. 0.15 nm
• B. 0.34 nm
• C. 3.0 Å
• D. 3.1 Å

Hint:

Remember that the rise per base pair in the DNA double helix (B-DNA) is 0.34 nm (3.4 Å), and one full turn of the helix contains about 10.5 base pairs.

Answer 1

The Correct Option is B

Step 1: DNA Structure.
DNA is a double helix composed of stacked nucleotides. Each nucleotide comprises a base, sugar, and phosphate group, arranged to form a uniform helical structure.
Step 2: Nucleotide Spacing.
The axial distance between consecutive nucleotides in the helix is 0.34 nanometers (nm), equivalent to 3.4 Å. X-ray crystallography, including work by Rosalind Franklin, has validated this distance.
Step 3: Incorrect Distances.
- Option (1) 0.15 nm: This distance is insufficient for nucleotide stacking.
- Option (3) 3.0 Å: This value is slightly shorter than the established distance.
- Option (4) 3.1 Å: This is inaccurate; the correct value is approximately 3.4 Å.
Therefore, 0.34 nm is the most accurate measurement.
Final Answer:
\[\boxed{0.34 \, \text{nm}}\]