Which of the following compounds is classified as an ester?

Ester compounds are characterized by the presence of a carbonyl group (C=O) adjacent to an ether linkage (–O–). In the realm of biochemistry, lipids, particularly triglycerides and phospholipids, often contain ester bonds formed from the reaction of fatty acids with alcohols, such as glycerol.

Lipids play crucial roles in biological systems, serving as energy storage molecules, structural components of cell membranes, and signaling molecules, and are categorized in part by their ester linkages. In contrast, proteins are made of amino acids linked by peptide bonds, nucleic acids consist of nucleotide monomers linked by phosphodiester bonds, and amino acids are the building blocks of proteins, but do not themselves have ester bonds. Therefore, the classification of lipids as esters precisely aligns with their structural characteristics and functional roles in living organisms.