Identifying Polar Uncharged Amino Acids

In the study of biomolecules, understanding the structure and function of amino acids is crucial. Amino acids are the building blocks of proteins and play vital roles in various biochemical pathways. One of the key characteristics of amino acids is their functional groups, which can significantly affect their reactivity and interactions.

Consider an amino acid that is classified as both polar and uncharged at physiological pH. Which of the following amino acids best fits this description based on its side chain structure?