A Level Biology Practice Exam

What type of interactions are involved in the tertiary structure of proteins?

1. only hydrophobic interactions and van der Waals forces

2. hydrogen bonds, disulfide bridges, ionic bonds, and hydrophobic interactions

3. wet and dry interactions based on environmental conditions

4. the folding of proteins due to pH changes

The correct answer is: hydrogen bonds, disulfide bridges, ionic bonds, and hydrophobic interactions

The tertiary structure of proteins is primarily stabilized by a variety of interactions that play crucial roles in maintaining the overall three-dimensional shape of the protein. This structure is the result of various non-covalent interactions as well as some covalent bonds that occur between the side chains of the amino acids. Hydrogen bonds form between polar side chains, contributing to the stability of the protein's folded form. Disulfide bridges, which are covalent bonds formed between cysteine residues, provide strong links that can hold parts of the protein together even through significant changes in the environment. Ionic bonds arise from the attraction between positively and negatively charged side chains, further enhancing the protein's stability. Hydrophobic interactions occur as non-polar side chains tend to cluster away from the aqueous environment, which helps in the formation of a compact structure. Together, these types of interactions ensure that the protein maintains its functional shape, allowing it to perform its biological roles effectively. Hence, the answer correctly encompasses all the key interactions involved in establishing the tertiary structure of proteins.