How are many lipids characterized chemically?

Many lipids are characterized chemically as esters. This classification arises from the structural features of lipids, such as triglycerides and phospholipids, which are composed of glycerol and fatty acids. In these molecules, the fatty acids form ester bonds with glycerol, resulting in the formation of triglycerides (fats and oils) when three fatty acid molecules are esterified with one glycerol molecule.

Phospholipids, key components of cell membranes, also exhibit this ester linkage where two fatty acid chains are linked to glycerol along with a phosphate group. Thus, the characteristic structures of lipids, dominated by these ester linkages, are fundamental to their biological functions and roles within organisms. Other classifications like polysaccharides, alcohols, and amino acids pertain to different groups of biomolecules; polysaccharides consist of sugar units, alcohols are hydroxyl compounds, and amino acids are the building blocks of proteins, none of which directly correlate to the primary chemical nature of lipids.