Human insulin is prepared by using genetic engineering (rDNA technology).
The steps involved in production of insulin are:
Isolation of desired gene: Human insulin gene is isolated from human tissue. The cells are removed and cultured. The cell is broken and DNA is isolated by breaking the nucleus. The desired gene is obtained by cutting DNA with the help of restriction endonuclease. DNA containing the desired gene is called passenger DNA.
Formation of recombinant DNA: Plasmids are usually used as vectors. The plasmid is cleaved open at a site with the help of restriction endonuclease. Now, the desired gene of interest is mixed with the plasmid DNA and joined by means of DNA ligase. The plasmid containing the desired gene is called recombinant DNA.
Gene Transfer to host: The recombinant DNA is introduced into a host cell (eg. E.coli). When the bacterial cell divided rapidly, the plasmid along with the desired gene is also amplified. Thus, several copies of the desired gene are produced. The desired gene is allowed to produce the desired product i.e. Insulin.