Explain what are the desirable characteristics of an ideal cloning vector used in rDNA technology

Explanation

A cloning vector is a small piece of DNA, taken from a virus, a plasmid, or the cell of a higher organism, that can be stably maintained in an organism and into which a foreign DNA fragment can be inserted for cloning purposes. The vector therefore contains features that allow for the convenient insertion or removal of a DNA fragment to or from vector, An ideal cloning vector must have following characteristics : (a) It must have an Origin of Replication (ORI) which is the sequence from which replication starts and the foreign gene linked to it will clone itself and it also controls the copy number of the linked DNA. (b) It must be small in size less than 10 kB. (c) It must be self-replicating inside host cell. (d) It must possess restriction site for Restriction Endonuclease enzymes. (e) It must have the cloning sites for the ligation of the alien DNA which is carried out at the recognition site. (f) Introduction of donor DNA fragment must not interfere with replication property of the vector. (g) It must possess some marker gene such that it can be used for later identification of recombinant cell. These will help in identifying and eliminating non-transformants and selectively permitting the growth of transformants. (h) It must possess multiple cloning site.