(1) Isolating a useful DNA segment from the donor organism.
(2) Splicing it into a suitable vector under conditions to ensure that each vector receives no more than one DNA fragment.
(3) Producing of multiple copies of his recombinant DNA.
(4) Inserting this altered DNA into a recipient organism.
(5) Screening of the transformed cells.
Vectors:
Vector in genetic engineering is usually a DNA segment used as a carrier for transferring selected DNA into living cells. These are as follows:
(1) Plasmid: Plasmid is extra chromosomal, closed circular double stranded molecules of DNA present in most eukaryotes. All plasmid carry replicons pieces of DNA that have the genetic information required to replicate. Plasmid pBR 322 was one of the first widely used cloning vectors, it contain both ampicillin and tetracycline resistance genes.
(2) Phage: It is constructed from the phage l chromosomes and acts as bacteriophage cloning vectors.
(3) Cosmid: The hybrids between plasmid and the phage l chromosome give rise to cosmid vectors.
(4) Beside all these there are artificial chromosomes like
(i) BACs (Bacterial Artificial chromosomes)
(ii) YACs (Yeast Artificial chromosomes)
(iii) MACs (Mammalian Artificial chromosomes) are very efficient vectors for eukaryotic gene transfers.
Application of recombinant DNA technology:
The technique of recombinant DNA can be employed in the following ways.
(1) It can be used to elucidate molecular events in the biological process such as cellular differentiation and ageing. The same can be used for making gene maps with precision.
(2) In biochemical and pharmaceutical industry, by engineering genes, useful chemical compounds can be produced cheaply and efficiently which is shown in table.