History.. how it all started and what it is all about..

30/09/2013 10:57

Recombinant DNA technology is the use of in vitro molecular techniques to isolate and manipulate fragments of DNA.  

In the early 1970s, the first successes in making recombinant DNA molecules were accomplished Stanley Cohen at Stanford University and Herbert Boyer at the University of California School of Medicine at San Francisco and their colleagues.

             

They were able to isolate and purify pieces of DNA in a test tube and then covalently link DNA fragments from two different sources.

 In other words, they constructed molecules called recombinant DNA molecules. They called the hybrid DNA molecules chimeras, after the mythological Chimera, a creature with the head of a lion, the body of a goat, and the tail of a serpent.

  Cohen and Boyer's experiment  -> (click here for animation)
In 1973 Stanley Cohen, Herbert Boyer, and Paul Berg did precisely this (figure 20.1). They inserted an amphibian (Xenopus laevis, the African clawed toad) gene encoding rRNA into the pSC101 plasmid. The plasmid got its name by being the 101st plasmid isolated by Stanley Cohen (plasmid Stanley Cohen 101, or pSC101). This plasmid, as previously described, contained a single site that could be cleaved by the restriction enzyme EcoRI, as well as a gene for tetracycline resistance (Tcr gene). The rRNA-encoding region was inserted into the pSC101 at the cleavage site by cleaving the rRNA region with EcoRI and allowing the complementary sequences to pair. This was the dawn of genetic engineering.
                               

 

Recombinant DNA technology is a set of molecular techniques for locating, isolating, altering, and studying DNA segments. The term recombinant is used because frequently the goal is to combine DNA from two distinct sources.

Genes from two different bacteria might be joined, for example, or a human gene might be inserted into a viral chromosome.

Commonly called genetic engineering, recombinant DNA technology now encompasses an array of molecular techniques that can be used to analyze, alter, and recombine virtually any DNA sequences.

Shortly thereafter, researchers were able to introduce such recombinant DNA molecules into living cells. Once inside a host cell, the recombinant molecules can be replicated to produce many identical copies of a gene—a process called gene cloning.

Recombinant DNA technology and gene cloning have enabled geneticists to probe relationships between gene sequences and phenotypic consequences, and thereby have been fundamental to our understanding of gene structure and function. 

 Most researchers in molecular genetics are familiar with recombinant DNA technology and apply it frequently in their work.

Significant practical applications of recombinant DNA technology also have been developed. These include exciting advances such as gene therapy, screening for human diseases,

recombinant vaccines, and the production of transgenic plants and animals in agriculture, in which a cloned gene from one species is transferred to some other species. Transgenic organisms have also been important in basic research.

Sources:

Content: Genetics, a conceptual approach(second edition), Benjamin A. Pierce

             Genetics, analysis and principles, Robert J. Brooker

Images: 

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https://www.mhhe.com/biosci/genbio/raven6b/graphics/raven06b/howscientiststhink/20-lab.pdf