STPM Biology - chapter 3: Revision essay question 12

Explain how human insulin can be synthesised by bacteria.

Answer

Human insulin can be synthesized by bacteria via the application of genetic engineering  techniques, such as the process of gene cloning. In the production of human insulin ,genetically modified bacteria are used to manufacture the insulin. The process by which the insulin is manufactured is as follows:

i) Firstly, messenger RNA (mRNA ) is extracted from the cells of human pancreatic tissues.

ii) The mRNA is treated with reverse transcriptase in order to convert the mRNA coding for insulin into DNA ,i.e., yo produce complementary DNA (cDNA ),with the help of DNA polymerase.

iii) Restriction edonucleases are used to cut and leave ‘sticky ’ ends, which are single strands, to the cDNA .

iv) A plasmid is removed from a bacterial cell and cut open at appropriate points with the help of restriction  endonucleases. The open portions of the plasmid will also have ‘sticky ’ ends, to which the Cdna IS THEN INSERTED USING DNA ligase.

v) The resultant plasmid now carried human DNA for insulin and is called a plasmid vector. It is re-inserted into the plasmid-free bacterial cell.

vi) Once back in the bacterial cell, the plasmid will replicate and use the new gene for making insulin.

Assignment submitted by C.,L.,Ooi, W.Y.,Ng, K.Q., Beh, Y.H.,Beh, Dhevan  2011/2012 (IBM)