Q.Explain how recombinant Insulin can be produced.

Step 1. Identify and isolate the gene: the human insulin-producing gene is identified within the DNA of a human pancreas cell. Step 2. Prepare the vector: a bacterial (E. coli) plasmid is cut open using restriction enzymes, creating a site into which foreign DNA can be inserted. Step 3. Build the recombinant DNA: the human insulin gene is spliced into the cut plasmid, forming recombinant DNA that now carries the human insulin gene alongside the bacterium's own plasmid sequence. Step 4. Transform the host: this recombinant plasmid is introduced into a bacterial (E. coli) cell, creating a recombinant bacterium capable of expressing the human insulin gene. Step 5. Culture and express: the recombinant bacteria are grown and multiplied in a fermentation tank, where they manufacture the insulin precursor protein, pre-pro-insulin — a single chain carrying a leader (signal) peptide, the A and B insulin segments, and a connecting C-chain. Step 6. Process the precursor: after translation, the leader sequence is removed and the C-chain is excised, leaving the mature A and B polypeptide chains correctly linked together by disulphide (S-S) bonds — the f …

Walk through the insulin-production pipeline in Fig. 10.1's order: gene isolation, plasmid cutting, recombination, bacterial transformation, fermentati …

• Skipping the pre-pro-insulin processing step (leader sequence removal and C-chain excision), jumping straight from 'gene inserted' to 'insulin produced'. …