The DNA recombinant technology is also known as genetic engineering. It deals with the alteration of the genetic makeup of cells by deliberate and artificial means. The various vectors used in this technique are plasmid vector, bacteriophage vector, cosmid vector, BACs ( bacterial artificial chromosomes ), YACs ( yeast artificial chromosomes ), MACs ( mammalian artificial chromosomes ). Some of the enzymes used in genetic engineering are BAM HI, Bgl II, Eco RI, Hae II and Hind III.