# NEET Zoology Biomolecules Questions Solved

BOARD

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) $\mathrm{\alpha }$-Helix structure : Intramolecular H-bonds present between the C=O of one amino acid and

N-H of fourth amino acid.

(ii) $\mathrm{\beta }$-Pleated sheet structure : The two neighbouring polypeptide chains are held together by inter-

molecular H-bonds.

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