PRIMARY PROTEIN STRUCTURE

This is the sequence of amino acids in a polypeptide chain. These are bonded together by strong covalent bonds. 

SECONDARY PROTEIN STRUCTURE

The secondary structure is the shape that the polypeptide chain forms as a result of hydrogen bonding. Hydrogen bonds can only form between nitrogen, oxygen, hydrogen and flourine.

These bonds form spiral shapes called alpha helicles or beta pleated sheets.

TERTIARY STRUCTURE

This is the folding of the secondary structure to form a complex 3 dimensional structure. This is achieved by the following bonding:

1. Disulphide bonds

2. Ionic bonds

3. Hydrogen bonds