Genetic Marker - Insulin Production

Insulin Production

Genetic markers also play a role in genetic engineering, as they can be used to produce normal, functioning proteins to replace defective ones. The damaged or faulty section of DNA is removed and replaced with the identical, but functioning, gene sequence from another source.

This is done by removal of the faulty section of DNA and its replacement with the functioning gene from another source, usually a human donor. These gene sections are placed in solution with bacterial cells, a small number of which take up the genetic material and reproduce the new DNA sequence. Engineers need to know which bacteria have been successful in duplicating these genes so another gene is added, altering the bacteria's resistance to antibiotics. Replica plating or a fermenter is used to grow enough bacteria to test resistance to antibiotics. It is important that the cultures are not mixed.

This process can be used as a treatment for diabetes mellitus. Artificial plasmid DNA often has two resistancy genes: one for tetracycline and one for ampicillin. The insulin gene can be inserted in the middle of the ampicillin gene after it has been removed using restriction endonucleases. If the gene has been taken up, the bacteria both produces insulin and is also no longer ampicillin resistant. The bacteria are then allowed to grow on an agar plate containing a culture medium. The bacteria grow and produce colonies on the agar jelly. A piece of filter paper can be placed onto the top of this agar plate so that the exact positions of the colonies are remembered. This produces a copy which can then be transferred onto a second agar plate containing ampicillin. All of the bacteria that are not resistant to ampicillin will die. These locations on the second plate show the places on the first plate where bacteria are not resistant and, therefore, produce insulin. Another similar method is followed, in which an epitope sequence is added to insert. When the insert is expressed so is the epitope. Then this epitope can be effectively bound using an antibody on a filter paper. And the expressing colonies can be easily selected.