What determines the tertiary structure of proteins?

• A. The sequence of amino acids
• B. The presence of disulfide bridges only
• C. The number of peptide bonds
• D. Hydrogen bonds, ionic bonds, and hydrophobic interactions

Answer: (D)

Verified step by step guidance

1. Understand that the tertiary structure of a protein refers to its three-dimensional shape, which is crucial for its function.
2. Recognize that the sequence of amino acids, known as the primary structure, influences how the protein will fold into its tertiary structure.
3. Identify the types of interactions that stabilize the tertiary structure: hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions.
4. Hydrogen bonds form between polar side chains, ionic bonds form between charged side chains, and hydrophobic interactions occur when nonpolar side chains cluster away from water.
5. Disulfide bridges, which are covalent bonds, can also form between cysteine residues, further stabilizing the protein's structure.