a group of a fat-like nature which are essential components of living cells. They contain phosphorus and usually nitrogen and on hydrolysis give fatty acids, phosphoric acids and bases such as choline. The phospholipids consist of a number of different species usually with glycerol as the "back-bone". They include lecithins, cephalins and sphingomyelins. Phospholipids are amphoteric and mainly exist as components of cell membranes. Lecithins, cephalins and related compounds are also more specifically known as phosphatides as they are derivatives of phosphatidic acid
