Write brief notes on the Cloning plasmid .

Explanation

Plasmids were discovered by William Hayes and Joshua Lederberg (1952). These are extrachromosomal, self-replicating, usually circular, double-stranded DNA molecules, found naturally in many bacteria and also in some yeast. Although plasmids are usually not essential for normal cell growth and division, they often confer some traits on the host organism. For example, resistance to certain antibiotics or toxins that can be a selective advantage under certain conditions.
The plasmid molecules may be present as 1 or 2 copies or in multiple copies (500-700) inside the host organism. These naturally occurring plasmids have been modified to serve as vectors in the laboratory. The most widely used, versatile, easily manipulated vector PBR 322 is an ideal plasmid vector .