The “outside” of a protein structure is composed of hydrophobic amino acid side chains that interact with water molecules surrounding the protein. True False
The correct answer and explanation is:
Answer: False
Proteins are composed of long chains of amino acids that fold into specific three-dimensional structures, and the interaction of these amino acid side chains with water plays a crucial role in determining the protein’s final shape and function. However, the “outside” of a protein structure, also known as the surface, is typically composed of hydrophilic (water-attracting) amino acid side chains rather than hydrophobic (water-repelling) ones. This arrangement is due to the way proteins fold and interact with their environment.
In an aqueous environment, hydrophilic amino acids, such as serine, glutamine, and lysine, are more likely to be exposed on the surface of the protein. These amino acids form hydrogen bonds with water molecules, allowing the protein to remain stable in solution. On the other hand, hydrophobic amino acids, such as leucine, phenylalanine, and valine, tend to cluster together in the interior of the protein, away from the water. This is because the hydrophobic side chains do not interact favorably with water molecules, and the protein folds in a way that minimizes such unfavorable interactions.
The folding of proteins is largely driven by the hydrophobic effect, where nonpolar (hydrophobic) side chains are driven toward the interior of the protein to avoid water, while polar (hydrophilic) side chains are more likely to be positioned on the exterior to interact with water molecules. This arrangement allows proteins to be stable in aqueous environments and carry out their functions effectively.
In summary, the statement that the “outside” of a protein is composed of hydrophobic side chains interacting with water is incorrect. The surface of a protein typically consists of hydrophilic amino acids that interact with water molecules, while hydrophobic side chains are found buried in the protein’s core.