question_answer 20)

  The most important feature in a plasmid to be used as a vector is (a) Origin of replication (On)                                       (b) presence of a selectable marker (c)presence of sites for restriction endonuclease (d) its size

Answer:

                  (a) All of the given features are important to facilitate cloning into a vector but out of them origin of replication (ori) is the most important one. This is due to the following reasons (i) Ori is a DNA sequence that is responsible for initiating replication. Any piece of DNA when linked to this sequence can replicate within the host cells. (ii) Ori also controls the copy numbers of the linked DNA.