What type of bond forms between two amino acids in a protein?

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

Answer: (D)

The bond that forms between two amino acids in a protein is called a peptide bond. This specific type of covalent bond is created during a dehydration synthesis (or condensation) reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water. This reaction results in the formation of a dipeptide, and as more amino acids link together, they form longer chains, ultimately creating polypeptides and proteins. Peptide bonds are crucial for the primary structure of proteins and significantly influence a protein's ultimate shape and function.

While hydrogen and ionic bonds do play important roles in maintaining the overall structure of proteins through interactions between various parts of the polypeptide chain or with other molecules, they are not the bonds that directly link amino acids together. Covalent bonds are a broader category that includes peptide bonds; however, the specific term that defines the bond between two amino acids is indeed the peptide bond.