Lipids are water-insoluble biomolecules of cells that have high solubility in non-polar organic solvents. Lipids have many biological roles: they serve as fuel molecules, as highly concentrated energy stores, and as components of membranes. We are interested in the lipids that are components of membranes. There are three kinds of membrane lipids, phospholipids, glycolipids, and cholesterol.
Glycolipids and phospholipids are composed of fatty acids chains that are connected to a glycerol backbone. The fatty acid chains usually contain an even number of carbon atoms in a linear fashion (the 16- and 18-carbon chains are the most common). Fatty acids can be saturated or unsaturated (containing one or more double bonds).
