Question

How many hydrogen bonds form between adenine and thymine in complementary base pairing?

Options

• 2 hydrogen bonds

• 3 hydrogen bonds

• 1 hydrogen bond

• 4 hydrogen bonds

Answer 1

Adenine (A) pairs with thymine (T) through exactly 2 hydrogen bonds. In contrast, guanine (G) pairs with cytosine (C) through 3 hydrogen bonds. These hydrogen bonds provide horizontal stability to the double helix while being weak enough to allow strand separation during DNA replication and transcription.