1. Lipids are organic molecules that are soluble in organic solvents such as chloroform and methanol and are insoluble in water. Lipids means fat. They are the principal component of cell membrane including cell walls.
2. Lipids act as energy source for living systems. Fat provide 2 – 3 fold higher energy compared to carbohydrates or proteins.
3. Based on their structure, lipids can be classified as simple lipids, compound lipids and derived lipids.
4. simple lipids can be further classified into fats, which are esters of long chain fatty acids fats, with glycerol (triglycerides) and waxes which are esters of fatty acid with long chain monohydric alcohols (Bees wax)
5. Compound lipids are the esters of simple fatty acid with glycerol which contain additional group. Based on the groups attached, they are further classified into phospholipids, glycolipids and lipoproteins. Phospho lipids contain a phospho ester linkage while the glycolipids contain a sugar molecule attached. The iipo proteins are complexes of lipid with proteins.