What are lipids? Classify them and give at least one example of each.

Lipids:

Lipids are a group of heterogeneous compounds like fats, oils, steroids, waxes, etc. They are macro-biomolecules. These are group of substances with greasy consistency with long hydrocarbon chain containing carbon, hydrogen and oxygen. 

Lipids are classified into: 

1. Saturated fatty acids: They contain single chain of carbon atoms with single bonds. 

E.g. Palmitic acid, stearic acid 

2. Unsaturated fatty acids: 

They contain one or more double bonds between the carbon atoms of the hydrocarbon chain. 

a. Simple lipids: These are esters of fatty acids with various alcohols. 

E.g. Fats, wax

b. Compound lipids: 

These are ester of fatty acids containing other groups like phosphate (Phospholipids), sugar (glycolipids), etc. 

E.g. Lecithin 

c. Sterols: 

They are derived lipids. They are composed of fused hydrocarbon rings (steroid nucleus) and a long hydrocarbon side chain. 

E.g. Cholesterol, phytosterols.