8.18—Recombinant DNA production

Recombinant DNA is formed when DNA from different sources is joined. A restriction enzyme cuts the desired gene and vector, complementary ends pair, and DNA ligase seals the sugar-phosphate backbone.

PCR can amplify the target before insertion, while a plasmid provides replication or expression signals in the host. The construct must be introduced into cells and selected or screened.

A gene coding for insulin can be joined to a bacterial plasmid; the plasmid is then transferred into bacteria where the gene may be expressed.

Cutting DNA is not the same as expressing it. A recombinant construct needs a compatible host, promoter and verification before useful protein is produced.