Which bonds stabilize complementary base pairing in nucleic acids?

• A. Ionic bonds
• B. Covalent bonds
• C. Hydrogen bonds
• D. Peptide bonds

Answer: (C)

Hydrogen bonds stabilize complementary base pairing. They form specifically between paired bases (A with T/U and C with G), with two hydrogen bonds in A–T/U pairs and three in C–G pairs. These bonds are strong enough to keep the two DNA strands together, yet weak enough to break during replication and transcription, allowing the genetic information to be read and copied. Ionic bonds, covalent bonds, and peptide bonds do not mediate the base pairing interactions: covalent bonds hold the nucleotide units and sugar–phosphate backbone together, peptide bonds link amino acids, and ionic interactions are general electrostatic attractions not responsible for the specific pairing between bases.