Which three amino acids have uncharged aromatic side chains?

The amino acids that have uncharged aromatic side chains include tryptophan, phenylalanine, and tyrosine. These amino acids are characterized by the presence of a benzene ring or a related structure in their side chains, which gives them their aromatic properties.

Tryptophan contains an indole structure, phenylalanine has a simple phenyl group, and tyrosine has a phenolic hydroxyl group that does not carry a charge at physiological pH, making all three of them neutral in terms of charge. This uncharged nature is significant in protein structure and function, particularly in stabilizing protein folding through hydrophobic interactions and allowing for aromatic stacking in protein structures.

In contrast, the other choices include amino acids with either charged side chains or no aromatic characteristics, making them unsuitable in the quest for uncharged aromatic side chains. Therefore, the correct choice of tryptophan, phenylalanine, and tyrosine stands out due to their specific side chain structures and their uncharged status at physiological conditions.