Definition of Lipids
Lipids have been defined as a heterogeneous group of naturally occurring substances that are insoluble in water but soluble in organic solvent such as ether, chloroform, benzene, and acetone. All lipids contain phosphorus and nitrogen. Most lipids are soft solids or liquids at room temperature and are difficult to crystallize.
The major classes of lipids can be summarized as follows:
Simple Lipids (esters of fatty acids and alcohols)
-Fat and oils (esters of glycerol and fatty acids)
-Waxes (esters of long chain monohydroxy alcohols and fatty acids)
Compound Lipids (simple lipids conjugated with nonlipid molecules)
Phospholipids (esters containing phosphoric acid in place of one mole of fatty acid) -Phosphoglycerides
-Sphingolipids
-Inositol phosphatides
Glycolipids (compounds of carbohydrate fatty acids and sphingosinol)
Lipoproteins (complexes of various lipids and proteins)
Derive Lipids (product of hydrolysis of lipids)
-Fatty acids
-Alcohols
-Hydrocarbons
-Fat-soluble vitamins
Definition of Lipids