Question

In one helix of DNA, minimum and maximum number of hydrogen bonds present between nitrogen bases:

• A. 20 and 20
• B. 20 and 30
• C. 30 and 20
• D. 30 and 40

Hint:

DNA base pairing follows Chargaff’s rule:
A pairs with T (2 bonds), and G pairs with C (3 bonds).

Answer 1

The Correct Option is B

Step 1: Understanding Hydrogen Bonds in DNA
DNA consists of two strands forming a double helix, where nitrogenous bases pair via hydrogen bonds:
- Adenine (A) pairs with Thymine (T) → 2 hydrogen bonds
- Guanine (G) pairs with Cytosine (C) → 3 hydrogen bonds
Step 2: Calculating Hydrogen Bonds in One Helix
- The minimum number of hydrogen bonds (when more A-T pairs exist) is 20.
- The maximum number of hydrogen bonds (when more G-C pairs exist) is 30.
Step 3: Identifying the Correct Answer
Correct answer: 20 and 30 hydrogen bonds in one helix.