[Campbell Biology P.130] Hydrophobic interactions are crucial for the folding of a polypepti... | Practice Question
Hydrophobic interactions are crucial for the folding of a polypeptide into its functional tertiary structure, particularly in an aqueous cellular environment. Why are these interactions described as "somewhat misleadingly" named in the text, and what is their underlying cause?
A: They are misleading because they are not true "attractions" but rather result from the exclusion of nonpolar substances by water, forcing them together. Their underlying cause is the tendency of water molecules to maximize hydrogen bonding with each other.
B: They are misleading because they are actually strong covalent bonds formed between hydrophobic side chains, contrary to their name. Their underlying cause is the sharing of electrons between carbon and hydrogen atoms.
C: They are misleading because they occur exclusively in non-aqueous environments. Their underlying cause is the repulsion between polar and nonpolar molecules.
D: They are misleading because they are the weakest type of interaction, making them insignificant for protein stability. Their underlying cause is random molecular collisions.
Explanation
The text explains that hydrophobic interactions are "somewhat misleadingly" named because they are not true attractions between nonpolar molecules. Instead, they result from the exclusion of nonpolar substances by water molecules, which prefer to interact with each other maximizing hydrogen bonding . This exclusion forces the nonpolar groups together, forming clusters at the protein's core, away from water.