Genetic engineering involves the manipulation of the DNA of an organism. DNA is made of two long polymers that are linked together to form a double helix shaped structure. DNA is made of sugar, phosphate and nitrogen bases.
Different segments of the DNA encode the information for the production of different protein molecules. If the DNA responsible for the production of a particular protein can be identified and isolated as an independent unit, it can be used to start the production of various proteins that are helpful in ensuring the health of humans.
Recombinant DNA (or rDNA) technology is one way in which genetic engineering is done. Scientists first study the DNA of humans and determine the segment that is responsible for the creation of a particular protein. This is then isolated. The next stage involves the insertion of the DNA segment into that of a vector. Vector refers to DNA, usually that of a virus, from which a segment can be removed and replaced by the DNA segment that had been isolated earlier. Using the vector allows the isolated DNA segment to exhibit its characteristics and also have the ability to reproduce. In a later stage, the vector has to be inserted into a host. The role of virus in rDNA technology is limited till the creation of the vector.