(i) Why was a bacterium used in the first instance of the construction of an artificial recombinant DNA molecule ?
(ii) Name the scientists who accomplished this and how ?

Explanation

(i) A bacterium salmonella typhimurium was used in the first instance of construction of artificial recombinant DNA molecule because of the possibilities of linking agene encoding antibiotic resistance with a native plasmid of the bacterium. This was future made possible by the availability of restriction enzymes and the enzyme DNA ligase.
(ii) Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene by cutting out a piece of DNA from a plasmid which was responsible for conferring antibiotic resistance. The cutting of DNA at specific sites was possible with the availability of restriction enzymes. The cut DNA was the linked with the plasmid DNA using the enzyme DNA ligase. The plasmid DNA acts as vector to transfer the piece of DNA attached to it.