Describe what you understand by primary structure and secondary structure of proteins. (2 marks)
Primary structure of proteins : Proteins may have one or more polypeptide chains. Each polypeptide in a protein has amino acids linked with each other in a specific sequence which is known as primary structure of protein.
Secondary structure of proteins : The conformation which the polypeptide chains assume as a result of hydrogen Londing is called the secondary structure of the protein.
Depending upon the size of the R groups, the two different secondary structures are possible which are :
(i) -Helix structure : Intramolecular H-bonds present between the C=O of one amino acid and
N-H of fourth amino acid.
(ii) -Pleated sheet structure : The two neighbouring polypeptide chains are held together by inter-