7.3.1 Recombinant DNA and Genetic Engineering

7.3.1 Recombinant DNA and Genetic Engineering

Increased knowledge about how DNA molecules function under various chemical conditions has opened the door to the field of technology called genetic engineering or biotechnology. Techniques now exist whereby a “foreign” gene can be added to an organism, and the organism will produce the protein associated with the added gene.

The example of benefits that can come from genetic engineering is the production of human insulin. For many years, because of the very limited availability of human insulin, the insulin used by diabetics was obtained from the pancreases of slaughterhouse animals. Such insulin is structurally very similar to human insulin and can be substituted for it. Today, diabetics can also choose to use “real” human insulin produced by genetically altered bacteria. Such “genetically engineered” bacteria are grown in large numbers, and the insulin they produce is harvested in a manner similar to the way some antibiotics are obtained from cultured microorganisms. Human growth hormone is another substance that is now produced by genetically altered bacteria.

Genetic engineering procedure involves a type of DNA called recombinant DNA. Recombinant DNA is DNA that contains genetic material from two different organisms.

The bacterium E.coli which is found in the intestinal tract of humans and animals is the organism most often used in recombinant DNA experiments. Yeast cells are also used, with increasing frequency, in this research.

In addition to their chromosomal DNA, E.coli (and other bacteria) contains DNA in the form of small, circular, double-stranded molecules called plasmids. These plasmids, which carry only a few genes, replicate independently of the chromosome. Also, they are transferred relatively easily from one cell to another. Hence plasmids from E. coli are used in recombinant DNA work.

The procedure used to obtain E.coli cells that contain recombinant DNA involved the following steps

Last modified: Wednesday, 22 February 2012, 9:29 AM