All the information required to create the bodies of living organisms is found in a double helix shaped structure inside them. This, called DNA is made up of sugar, phosphate and a nitrogen base. Only four nitrogen bases, adenine (A), thymine (T), guanine (G), and cytosine (C) make up the DNA of every organism. They are differentiated only by a change in the number of bases and their arrangement.
If it is possible to identify the DNA structure responsible for the creation of a protein, it can be used to artificially produce the protein. One technique of doing this is called the recombinant DNA technology. This involves the identification and isolation of the DNA structure responsible for the creation of a specific protein. The next step is finding a vector that is usually DNA from a virus which can be modified to implant the isolated DNA while the modified DNA retains the ability to reproduce. The vector is then placed into a host which is usually a simple organism like bacteria.
The altered DNA placed in the host forces the production of protein that the host organism does not produce naturally. The host is chosen appropriately to ensure that it does not alter the new protein that is being produced and remains unaffected by it. Bacteria are very efficient in playing the role of a host. This makes them ideal hosts for the production of several medicines that humans require. One example is the hormone insulin that is essential for the survival of humans but people who have diabetes are unable to produce on their own. rDNA technology is used to produce artificial insulin that can be used by diabetics.