ABSTRACT
Structure and function Triacylglycerols (also called fats or triglycerides) consist of three fatty acid chains esterified to a glycerol backbone. Simple triacylglycerols have three identical fatty acids esterified to the glycerol backbone, while mixed triacylglycerols have two or three different fatty acid chains (Figure 1). Triacylglycerols constitute the major fuel store and the major dietary lipid in humans. Triacylglycerols are a highly concentrated energy
store. The energy yield from the complete oxidation of fatty acids is about 38 kJ g−1, compared with an energy yield of 17 kJ g−1 of carbohydrate or protein. The hydrophobic properties of fats make them insoluble in water, and they are stored in specialized cells called adipose cells (fat cells), which consist almost entirely of triacylglycerol. These cells are specialized for the synthesis and storage of triacylglycerols and for their mobilization into fuel molecules. Triacylglycerols are transported round the body in large lipid-protein particles called lipoproteins (Section K6).
