Amino acids are linked together by which type of bonds?

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

Answer: (B)

Linking amino acids into a chain happens through peptide bonds. A peptide bond is a covalent bond formed by a dehydration synthesis reaction between the carboxyl group of one amino acid and the amino group of the next, creating a new amide linkage and releasing a water molecule. This bond is stronger than hydrogen or ionic interactions and forms the backbone of the growing polypeptide. The peptide bond also has resonance that gives it partial double-bond character, making it planar and limiting rotation, which helps define the protein’s overall structure. Hydrogen bonds and other interactions stabilize the folded shapes that result, but they do not join amino acids together.