Lipids

Lipids are a diverse group of compounds, present as structural components of cell membranes and insulation material in warm blooded animals. Besides, they are physiologically important as energy storage molecules and as participants in oxidative phosphorylation process. They are insoluble in water and soluble in organic solvents, such as ether, chloroform and benzene. Because of their heterogeneous nature, it is difficult to define them in certain terms. However, neutral fats and oils derived from animal and plant sources are called neutral lipids, which on hydrolysis yield glycerol and fatty acids. Thus lipids are fatty acid esters of glycerol. Many lipoidal compounds such as phospholipids are essential components of biological membranes. A class of lipids called steriods participate in the structures of membranes and also function as hormones.

Class

1.    fatty acids

a.    Saturated fatty acids
b.    Unsaturated fatty acids

2.    Glycerol lipids

a.    Neutral lipids
b.    Phospholipids
c.    Plasmalogens

3.    Lipids devoid of glycerol

a.    Sphingolipids
b.    Waxes
c.    Steroids
d.    Terpences

4.    Complex lipids

a.    Lipoproteins
b.    Lipopolysaccharides
c.    Proteolipids
d.    Phosphatidopeptides