Select incorrect statement, regarding chemical structure of insulin.

Select incorrect statement, regarding chemical structure of insulin.
  1. C-peptide is not present in mature insulin molecule.
  2. Polypeptide chains A and B are linked by disulphide bridges.
  3. Mature insulin molecule consists of three polypeptide chains - A, B and C.
  4. Insulin is synthesized as prohormone which contains extra stretch of C-peptide.

Solution

Option (3) is the answer because mature insulin does not contain C-peptide chain which is removed during maturation of pro-insulin into insulin. So, it contains only two polypeptide chains $\mathrm{A}$ and $\mathrm{B}$. Option (1) is not the answer because C-peptide is absent in mature insulin molecule. Option (2) is not the answer because polypeptide chains A and B are linked disulphide bridges. Option (4) is not the answer because an extra stretch C-peptide is not present in mature insulin but present in pro-insulin.

Asked in: NEET 2023 (Manipur)

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