Classification:
Based on their chemical composition, lipids are classified as follows:
(A) Simple lipids (homo lipids): Simple lipids are alcohol esters of fatty acids which include,
1. Neutral fats (glycerides): Also known as triglcerides, these are triesters of fatty acids and glycerol.
2. Waxes: These are esters of fatty acids with long chain monohydroxy alcohols.
These have higher melting points than neutral fats.
(B) Compound lipids (heterolipids): Lipids with additional groups are called compound lipids. These include:
1. Phospholipids (phosphatids): These contain additional groups e.g., a phosphoric acid, nitrogen containing bases and other substituents.
2. Glycolipids: These are esters of fatty acids with carbohydrates, and may contain nitrogen but no phosphorus.
(C) Derived lipids: These are the substances derived from simple and compound lipids by hydrolisis. These include fatty acids, fatty alcohols, mono and digglycerides, steroids, terpenes and carotenoids.