Question

Some of the steps involved in production of humulin are
given below. Choose the correct sequence.
(i) Synthesis of insulin gene artificially
(ii) Culturing recombinant $E.coli$ in bioreactors
(iii) Purification of humulin
(iv) Insertion of human insulin gene into plasmid
(v) Introduction of recombinant plasmid into $E.coli$
(vi) Extraction of recombinant gene product from $E.coli$

• A. i, iv, v, ii, vi, iii
• B. iii, v, ii, i, vi, iv
• C. ii, i, iv, iii, v, vi
• D. i, iii, v, vi, ii, iv

Answer 1

The correct option is A i, iv, v, ii, vi, iii

Introduction to humulin
Humulin is a genetically engineered man-made insulin produced in $E.coli$. It consists of A and B peptide chains and does not require further processing to remove C peptide.

Production of humulin
The following steps are involved in the production of humulin:

(i) Insulin gene is artificially synthesised using genetic engineering.

(iv) A suitable expression vector, plasmid, is selected and human insulin gene encoding for human A and B peptide chains is inserted into the plasmid separately. This results in the formation of recombinant plasmids.

(v) Competent $E.coli$ cells are then transformed by introducing recombinant plasmids.

(ii) Recombinant $E.coli$ cells which have successfully taken up recombinant plasmids are cultured on a large scale in bioreactors.

(vi) Recombinant gene products such as human A and B insulin peptides are extracted from $E.coli$.

(iii) A and B insulin peptides are joined together with disulfide bonds and humulin is purified.

Final answer
(B) i, iv, v, ii, vi, iii