programming presentation and need the explanation and answer to help me learn.

Insulin is a vital hormone secreted by the pancreas to regulate glucose levels in the blood. Through biotechnological tools, insulin can be produced in laboratory conditions. Here’s how it is done:
STEP 1: SELECTION OF CELL
An E. coli cell is chosen as the cell for this experiment. E. coli cells have two types of chromosomes – the bacterial chromosome and plasmids.
STEP 2: GENE INSERTION
The gene responsible for insulin production is extracted from human cells and inserted into the plasmid. The plasmid acts as a vector for the insulin gene.
STEP 3: RESTRICTION ENDONUCLEASE TREATMENT
Both the plasmid and the insulin gene are treated with restriction endonucleases, enzymes that can break double-stranded DNA. This results in the production of sticky ends.
STEP 4: RECOMBINANT DNA FORMATION
The sticky ends of the plasmid and the insulin gene can easily combine to form recombinant DNA, which carries the foreign insulin gene.
STEP 5: RECOMBINANT CELL CREATION
The recombinant DNA is inserted into a plasmid-free E. coli cell, resulting in the creation of a recombinant cell.
STEP 6: CULTURING
The recombinant cells are cultured in fermenters to allow for insulin production.
STEP 7: INSULIN EXTRACTION
Insulin is extracted from the cultured cells and can be used to treat patients who cannot produce insulin naturally.
Pro Insulin vs Insulin
Insulin is initially synthesized in the form of pro insulin, which is an inactive form of the hormone. Post-translational modifications are required to convert pro insulin into the active form of insulin.
DIFFERENCE BETWEEN PRO INSULIN AND INSULIN
Pro Insulin consists of three chains: A chain, B chain, and C peptide chain. Insulin only consists of A and B chains.
Disulfide bonds are present in both Pro Insulin and Insulin.
In post-translational modification, the C peptide chain is removed from Pro Insulin, resulting in the formation of Insulin.
Therefore, the correct answer to the given question is option C, as the C peptide chain is not present in Insulin.
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