Question

29.
Which of the following statements is not
correct?
The proinsulin has an extra peptide called
C-peptide.
The functional insulin has A and B chains
linked together by hydrogen bonds.
(3)
Genetically engineered insulin is produced
in E-Coli.
(4)
In man insulin is synthesised as a
proinsulin.​

Answer 1

The incorrect statement is the functional insulin has A and B chains linked together by hydrogen bonds.

Answer:

Option 2 is incorrect.

KEY:

The functional insulin has A and B chains linked together by DISULPHIDE bonds.

Explanation:

• The hormone insulin in man is usually synthesized in inactive form called pro insulin.

• This insulin pro hormone is functionally inactive.

• The pro insulin has three polypeptide chains namely A, B and C

• For the insulin to become active, the C peptide should be removed from pro insulin.

• So the mature and active insulin contains only A and B polypeptides linked together by disulphide bonds

• The deficiency of insulin hormone causes diabetes mellitus.

• Such person who are unable to produce sufficient insulin hormone can be treated by introducing insulin artificially in their body.

• This can be achieved by genetic engineering process.

• An American company called ELI LILLY succeeded in producing genetically engineered insulin in E.Coli