Biotechnology
The word biotechnology was coined in 1919 by Karl Ereky to apply to the interaction of biology with human technology. Today, it comes to mean a broad range of technologies from genetic engineering (recombinant DNA techniques), to animal breeding and industrial fermentation. Accurately, biotechnology is defined as the integrated use of biochemistry, microbiology, and engineering sciences in order to achieve technological (industrial) application of the capabilities of microorganisms, cultured tissue cells, and parts thereof.
The nature of biotechnology has undergone a dramatic change in the last half century. Modern biotechnology is greatly based on recent developments in molecular biology, especially those in genetic engineering. Organisms from bacteria to cows are being genetically modified to produce pharmaceuticals and foods. Also, new methods of disease gene isolation, analysis, and detection, as well as gene therapy, promise to revolutionize medicine.
In theory, the steps involved in genetic engineering are relatively simple. First, scientists decide the changes to be made in a specific DNA molecule. It is desirable in some cases to alter a human DNA molecule to correct errors that result in a disease such as diabetes. In other cases, researchers might add instructions to a DNA molecule that it does not normally carry: instructions for the manufacture of a chemical such as insulin, for example, in the DNA of bacteria that normally lack the ability to make insulin. Scientists also modify existing DNA to correct errors or add new information. Such methods are now well developed. Finally, scientists look for a way to put the recombinant DNA molecule into the organisms in which it is to function. Once inside the organism, the new DNA molecule give correct instructions to cells in humans to correct genetic disorders, in bacteria (resulting in the production of new chemicals), or in other types of cells for other purposes.
Genetic engineering has resulted in a number of impressive accomplishments. Dozens of products that were once available only from natural sources and in limited amounts are now manufactured in abundance by genetically engineered microorganisms at relatively low cost. Insulin, human growth hormone, tissue plasminogen activator, and alpha interferon are examples. In addition, the first trials with the alteration of human DNA to cure a genetic disorder began in 1991.
Molecular geneticists use molecular cloning techniques on a daily basis to replicate various genetic materials such as gene segments and cells. The process of molecular cloning involves isolating a DNA sequence of interest and obtaining multiple copies of it in an organism that is capable of growth over extended periods. Large quantities of the DNA molecule can then be isolated in pure form for detailed molecular analysis. The ability to generate virtually endless copies (clones) of a particular sequence is the basis of recombinant DNA technology and its application to human and medical genetics.
A technique called positional cloning is used to map the location of a human disease gene. Positional cloning is a relatively new approach to finding genes. A particular DNA marker is linked to the disease if, in general, family members with certain nucleotides at the marker always have the disease, and family members with other nucleotides at the marker do not have the disease. Once a suspected linkage result is confirmed, researchers can then test other markers known to map close to the one found, in an attempt to move closer and closer to the disease gene of interest. The gene can then be cloned if the DNA sequence has the characteristics of a gene and it can be shown that particular mutations in the gene confer disease.
An example of a human disease gene that was identified by positional cloning is the gene for Huntington disease. The discovery of Huntington disease linkage to known markers on chromosome four allowed individuals at risk in affected families to be tested to see if they inherited the same DNA sequences at these marker locations as affected family members. This information, provided with genetic counseling, indicated a more specific risk estimate than only knowing that the individual has a 50% chance of developing the disease.
Embryo cloning is another example of genetic engineering. Agricultural scientists are experimenting with embryo cloning processes with animal embryos to improve upon and increase the production of livestock. The first successful attempt at producing live animals by embryo cloning was reported by a research group in Scotland on March 6, 1997.
There is continuing debate around the moral and ethical limits on cloning human embryos. Currently, it is illegal to use federal research funds in the United States to clone human embryos. However, the debate was raised from an abstract theoretical plane to a concrete discussion of appropriate science policy when U.S. researchers made the surprise announcement that they had cloned a human embryo. This was the first documentation of a successful attempt at human embryo cloning. The human embryo that was cloned was not viable. The embryo and the clone were destroyed.
The prospects offered by genetic engineering have not been greeted with unanimous enthusiasm by everyone. Many believe that the hope of curing or avoiding genetic disorders is a positive advance. But some question the wisdom of making genetic changes that are not related to life-threatening disorders. Should such procedures be used for helping short children become taller or for making new kinds of tomatoes? Indeed, there are some critics who oppose all forms of genetic engineering. There are also concerns about genetic privacy, the effects of transgenic organisms on other organisms and the environment, and animal rights. As the technology available for genetic engineering continues to improve, debates over the use of these techniques in practical settings are almost certainly going to continue and escalate in the future.
Although genetic engineering is a very important component of biotechnology, it is not alone. Biotechnology has been used by humans for thousands of years. Some of the oldest manufacturing processes known to humankind make use of biotechnology. Beer, wine, and breadmaking, for example, all occur because of the process of fermentation. As early as the seventeenth century, bacteria were used to remove copper from its ores. Around 1910, scientists found that bacteria could be used to decompose organic matter in sewage. A method that uses microorganisms to produce glycerol synthetically proved very important in the World War I since glycerol is essential to the manufacture of explosives.
Hybridization is an example of biotechnology that does not depend on microorganisms. Farmers learned long ago that they could control the types of plant or animal bred by carefully selecting the parents. Today, there is hardly a fruit or vegetable in our diet that has not been altered by long decades of hybridization.
Modern principles of hybridization have made possible a greatly expanded use of biotechnology in agriculture and many other areas. One of the greatest successes of the science has been the development of new food crops that can be grown in a variety of less than optimal conditions. The dramatic increase in harvests made possible by these developments has become known as the green revolution. In the animal world, scientists are now using controlled breeding techniques and other methods from biotechnology to insure the survival of species that are threatened or endangered.
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