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Genetic engineering is the deliberate alteration of the genome of an organism, involving the insertion, deletion or substitution of sections of DNA. The DNA that is inserted may have been designed to code for a specific amino acid sequence in a protein or it may have been extracted from the genome of a different organism with particular desirable characteristics. The biological tools used by the genetic engineer are enzymes, which cut DNA (restriction enzymes), and bacteriophage viruses, which can be used to insert DNA into bacterial genomes. Once the required gene is inserted it can be cloned by multiplication of the bacterium, producing a quantity large enough for manipulation with restriction enzymes.
The products of the genetic engineer are of increasing commercial importance in biotechnology; for example, the human hormone insulin is now produced for medical use by bacteria which have the human gene for insulin inserted into their genome. The bacteria are grown on an industrial scale by fermentation and the gene product (the insulin) is harvested and purified. When an animal bears additional genes, which were inserted at the stage of the fertilized egg, all the daughter cells which make up the body carry the genes and the individual is said to be transgenic. Such animals are used extensively for research but also have great potential in agricultural biotechnology. RB
See also cloning; gene therapy; transformation.Further reading Bruce Alberts, Molecular Biology of the Cell; , Steven Prentis, Biotechnology. |
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