Inserting a piece of DNA
into a plasmid
(or another DNA vector
, but usually a plasmid) is refered to as DNA cloning. The plasmid with the new DNA is then placed in a bacterium
, which eventually processes it into a protein
. This lets any given protein be produced in as much quantity
as you have engineered bacteria.
A plasmid is cut with a restriction enzyme, leaving it with two sticky ends. The new DNA is also cut this way, and the two are mixed together. The sticky ends on the plasmids connect to the sticky ends on the new DNA, and they form a new plasmid that, when transcribed, makes whatever protein the new DNA codes for. The new plasmid is then stabilized with DNA ligase so the bacteria doesn't reject it. The plasmid is now recombinant DNA, and can be added to bacteria, which produce whatever protein is coded for.
Polymerase Chain Reaction is usually used to make many copies of the new vector, which the bacteria are exposed to. The bacteria uptake a few of the copies, and turn into your shiny new protein factory.
This process is to make insulin for use in combating diabetes, as well as other medicicinally useful enzymes. It is also used to study the effects of having too much of a given protein on a bacterium, or produce great quantities of other proteins for study. The need for a quantity of proteins for most kinds of genetic engineering makes DNA cloning the first step in many experiments.