Genetic Engineering Technology
Genetic engineering, or recombinant DNA technology, uses techniques of molecular biology to alter the genome of an organism. Typically, the alteration is the insertion of exogenous genetic material (deoxyribonucleic acid or, DNA) into the genome of the recipient organism.
Modern genetic engineering techniques speed up the natural processes of genetic alteration, which is the underpinning of evolution. Man has exploited genetic alteration for millennia, in bread making and the brewing of beer, and for hundreds of years in the selective breeding of animals or plants to enhance the development of desired characteristics. Selective breeding is a slow process, requiring generations for desired changes to spread through a population to reach numbers of economic significance.
The discovery of genetic material and the technical means to manipulate this material opened up a new era of genetic technology. The application of these techniques has sped up the genetic transfer and selection processes.
The facilitated fusion of cells of differing genetic composition is one technique of genetic engineering. Neighboring cell membranes are encouraged to fuse together by the application of a chemical agent such as polyethylene glycol or upon viral infection. The nuclei of the two cells remain intact, producing a binucleate cell. While the binucleate cell can commence the mitotic step of DNA replication, the inability of some of the chromosomes to lining up properly terminates development. Despite this, binucleate cells will still often produce proteins and polypeptides.
A drawback to cell fusion is the involvement of only two cells in the process. The deliberate and targeted insertion of exogeneous DNA into another cell, called transformation, is a more direct approach, resulting in quicker, more reliable, and more usable products. The inserted gene can be processed by the cell's transcription and translation machinery to produce the encoded protein. Often another gene, typically encoding resistance to an antibiotic, is included in the transformation. Bacteria are especially popular for transformation because of their ease of handling, because transformed cells can be selected using a growth medium containing the antibiotic, and because of the rapid reproduction time of bacteria. Large populations of recombinant bacteria and their recombinant protein product can be complied within a short time.
Gene cloning—making copies of an existing gene or organisms—is another significant genetic engineering technology. Cloning is of great importance in the engineering of bacteria to manufacture proteins of therapeutic or industrial importance. It is also a useful means of introducing genes into higher organisms, such as plants and animals. For eukaryotes, the procedure is referred to as transgenesis. As examples, transgenic cattle have been produced which manufacture human blood clotting agents, and transgenic plants in which the ripening process is delayed permit a riper product to reach the supermarket. Transgenic research in humans is possible, but is the subject of ethical scrutiny at the present time.
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