What are lipids primarily composed of?

Lipids are primarily composed of glycerol and fatty acids. This molecular structure is fundamental to the classification of lipids, which include fats, oils, waxes, and phospholipids. Glycerol is a three-carbon alcohol that provides a backbone to which fatty acids attach. The fatty acids, which consist of long hydrocarbon chains, can be saturated or unsaturated depending on the presence of double bonds. Together, glycerol and fatty acids form triglycerides, the primary form of stored energy in animals, and phospholipids, which are essential for cell membrane structure.

In addition to their basic composition, the characteristics of lipids, such as their hydrophobic nature, stem largely from the fatty acid chains. This property is critical for the formation of cell membranes, where phospholipids create a bilayer that forms a barrier between the cell and its environment.

Understanding the structure of lipids helps clarify their roles in biology, especially in energy storage, cellular structure, and signaling molecules.