What bonds connect amino acids to form polypeptide chains?

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

Answer: (B)

Peptide bonds connect amino acids to form polypeptide chains. This covalent bond forms when the amino group of one amino acid reacts with the carboxyl group of the next, releasing a water molecule in a dehydration synthesis. This linkage creates the protein’s backbone and allows the amino acid sequence to extend into a long chain. Other interactions, like hydrogen bonds, ionic bonds, and disulfide bridges, influence folding and stability but do not join the amino acids in the main chain. Hydrogen bonds stabilize secondary structures, ionic bonds form between charged side chains, and disulfide bonds link cysteine residues to stabilize tertiary or quaternary structures.