Primary and secondary structures of nucleic acid reveals

The primary structure is the covalently bonded structure of the molecule. It means and includes the sequence of amino acids, together with any disulphide bridges. All the general properties of the protein are determined, directly or indirectly, by the primary structure. Any type of  folding, hydrogen bonding, or catalytic activity depends on the nature of primary structure.

To understand the secondary structure of a protein, we focus on the hydrogen bonding.We imagine that the peptide chains as linear structures in nature, and they form orderly hydrogen-bonded arrangements. In particular, the carbonyl oxygen atoms form hydrogen bonds with the amide hydrogens. This tendency leads to orderly patterns of hydrogen bonding: the helix and the pleated sheet. These hydrogen-bonded arrangements, if present, are called the secondary structure of the protein.