Recombinant DNA
Recombinant DNA (rDNA) is artificially engineered DNA formed by joining sequences from two or more different organisms using molecular biology techniques such as restriction endonucleases and DNA ligase. The resulting hybrid molecule can be introduced into a host cell where it replicates and, if properly constructed, directs the synthesis of a desired protein. rDNA technology underlies the production of medicines such as human insulin, erythropoietin, and growth hormone.
Key Steps in Recombinant DNA Technology
| Step | Tool / Enzyme | Purpose | Example Enzyme |
|---|---|---|---|
| Cut DNA | Restriction endonuclease | Create specific sticky or blunt ends | EcoRI, HindIII |
| Ligate DNA | DNA ligase | Join insert into vector | T4 DNA Ligase |
| Transform host | Electroporation / heat shock | Introduce rDNA into bacteria | E. coli DH5α |
| Select transformants | Antibiotic plates | Identify cells with recombinant vector | Ampicillin, Kanamycin |
| Screen clones | PCR / colony hybridisation | Confirm correct insert | Taq polymerase |
| Express protein | Inducible promoter (IPTG) | Produce recombinant protein | T7 / lac promoter |
Interactive Tools
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Related Terms
Plasmid
A plasmid is a small, circular, double-stranded DNA molecule found in bacteria and some eukaryotes that replicates independently of chromosomal DNA. Plasmids typically carry accessory genes — such as antibiotic resistance genes — that confer a selective advantage to the host cell. In biotechnology, plasmids are widely used as vectors to clone, transfer, and express foreign genes in host organisms.
Gene Cloning
Gene cloning is the process of making multiple identical copies of a specific gene or DNA fragment by inserting it into a vector (such as a plasmid or bacteriophage) and replicating it inside a host organism, typically Escherichia coli. The technique involves cutting both the target DNA and the vector with the same restriction enzyme to generate compatible sticky ends, ligating them with DNA ligase, transforming the recombinant construct into host cells, and selecting colonies that contain the insert. Gene cloning is foundational to modern biotechnology and medicine, enabling the production of recombinant proteins (such as insulin), gene therapy constructs, diagnostic probes, and transgenic organisms.
From Latin "recombinare" (to combine again). The field was pioneered by Paul Berg, Stanley Cohen, and Herbert Boyer in 1972–1973 when they first successfully joined DNA from different organisms.