Which of the following best describes how amino acids affect the tertiary structure of a protein?

• A. Amino acids only determine the sequence of the protein, but not its three-dimensional structure.
• B. Amino acids affect only the primary structure, while the tertiary structure is determined solely by environmental factors.
• C. The side chains (R groups) of amino acids interact through various bonds and forces, determining the overall three-dimensional folding of the protein.
• D. The tertiary structure is formed by peptide bonds between amino acids, without involvement of side chain interactions.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of protein structure. Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. The tertiary structure refers to the three-dimensional folding of a protein, which is influenced by interactions between amino acid side chains (R groups).
2. Step 2: Recall the role of amino acids in protein structure. Each amino acid has a unique side chain (R group) that can interact with other side chains through various types of bonds and forces, such as hydrogen bonds, ionic bonds, van der Waals forces, and hydrophobic interactions.
3. Step 3: Analyze the options provided in the problem. Eliminate incorrect statements by comparing them to the established scientific understanding of how amino acids contribute to protein folding. For example, the statement that amino acids only determine the sequence but not the three-dimensional structure is incorrect because the sequence directly influences folding.
4. Step 4: Focus on the correct explanation. The tertiary structure is determined by the interactions between the side chains (R groups) of amino acids. These interactions drive the protein to fold into its functional three-dimensional shape.
5. Step 5: Conclude that the correct answer is: 'The side chains (R groups) of amino acids interact through various bonds and forces, determining the overall three-dimensional folding of the protein.' This explanation aligns with the scientific understanding of protein tertiary structure formation.