rDNA

Recombinant DNA, or rDNA, refers to DNA molecules that are formed by laboratory methods to join genetic material from different sources. The resulting sequences can encode, regulate, or otherwise alter biological function and would not occur naturally by mating and/or recombination alone. In typical rDNA workflows, a fragment of interest is isolated and inserted into a vector such as a plasmid or viral genome. The recombinant vector is introduced into a host cell, enabling replication and expression of the inserted gene. Enzymes such as restriction endonucleases and DNA ligases are commonly used to cut and join DNA fragments, while host cells provide cellular machinery for replication and protein production.

Early milestones in recombinant DNA research include the 1973 demonstration by Cohen and Boyer of biologically active plasmids in Escherichia coli, which established the practical viability of rDNA technology. In 1972 Paul Berg’s experiments led to a temporary moratorium and subsequent governance of the field; the Asilomar Conference of 1975 helped shape safety guidelines for recombinant DNA research.

Common vectors include plasmids for bacteria, viral vectors, cosmids, bacterial artificial chromosomes (BACs) and yeast artificial chromosomes (YACs). Gene delivery methods include transformation, transduction by viruses, electroporation, and chemical or physical methods. Expression depends on regulatory elements such as promoters, ribosome-binding sites, and selectable markers.

rDNA technology underpins modern biotechnology and medicine, enabling production of therapeutic proteins (insulin, growth factors), vaccines, gene therapy, and the development of genetically modified crops. It also facilitates functional genomics and basic research in gene regulation and protein engineering.

Safety considerations include risks of gene transfer to non-target organisms, environmental release, and the use of antibiotic resistance markers. Regulatory frameworks by national and international bodies govern laboratory practices and product approvals, with ongoing debates about ethics, access, and governance.