CBSE Class 12-science Answered
Cloning vectors are DNA molecules used as carriers for transferring a fragment of foreign DNA and capable of replicating inside the host cell independent of the control of chromosomal DNA. Plasmids and bacteriophages are commonly used cloning vectors.
The technique of using cloning vector in E. coli is as follows:
(i) The foreign DNA is linked to the sequence called ori (origin of replication) and is made to replicate within the host cell.
(ii) The ligation of foreign DNA is carried out at a restriction site present in the resistance genes.
(iii) The foreign DNA is then attached to the plasmid DNA (vector) with the help of enzyme ligase.
(iv) This recombinant DNA (rDNA) is inserted into the bacterial cell where it multiplies to produce multiple copies of the desired gene.