Which amino acids have hydroxyl groups in their side chains?

The correct answer highlights the amino acids that possess hydroxyl groups in their side chains, which is significant for their reactivity and involvement in various biochemical processes.

Serine, threonine, and tyrosine all contain a hydroxyl (-OH) group. This functional group is critical for post-translational modifications such as phosphorylation, which plays a key role in the regulation of protein function and cellular signaling pathways. For example, serine and threonine can be phosphorylated by kinases, impacting protein activity, interactions, and overall cellular function. Tyrosine also has similar properties, allowing for multiple forms of modification that can influence signaling pathways.

In contrast, the other answer choices do not contain amino acids with hydroxyl groups in their side chains. Phenylalanine, tryptophan, and methionine have aromatic side chains or sulfur groups but lack the hydroxyl functionality. Glutamate, proline, and glycine do not have hydroxyl groups either, and while leucine, isoleucine, and valine feature branched aliphatic side chains, they also do not contain hydroxyl groups. This understanding of amino acid properties is important in biochemistry and protein function.