DNA cloning is the starting point for many genetic engineering approaches to biotechnology research. The DNA cloning process involves isolation of a specific DNA fragment and its insertion into a plasmid vector for propagation, without alteration of the original DNA sequence. Most of these fragments are created either by digesting an existing piece of DNA with restriction enzymes or by targeting it via PCR.

After a DNA fragment is incorporated into the plasmid vector, the next cloning steps are transforming the plasmid into E. coli, recover the plasmid DNA, and check for correct insertion events.

Plasmid vectors in common use represent a smaller version of naturally occurring plasmids that include several basic features: a replication origin, a drug-resistance gene, and unique restriction sites to facilitate the insertion of DNA fragments.