Therefore, to solve this problem in vitro recombinant DNA (rDNA) technology has focused great attention due to many more future prospects. Thus, genetic engineering (= gene cloning, rDNA technology) can be defined as "changing of genes by using in vitro processes". A gene of known function can be transferred from its normal location into a cell (that of course, does not contain it) via a suitable vector. The transferred gene replicates normally and is handed over to the next progeny. On confirmation for its presence through biochemical procedures replica of the same cell (i.e. clones) can be produced. The derivation of procedures for the reintroduction of the foreign DNA fragment into a bacterium have lead to evolution of new technology i.e. the recombinant DNA technology, gene cloning, gene manipulation or genetic engineering.
Genetic engineering has been applied for the production of valuable polypeptides, insulin, interferon, growth hormones, and in the transfer of Nif genes, control of genetic diseases, etc.