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  Wikipedia: Genetic engineering

Wikipedia: Genetic engineering
Genetic engineering
From Wikipedia, the free encyclopedia.

"Genetic Engineering", "Genetic Modification" (GM), and "Gene Splicing" (once in widespread use but now deprecated) describe the process of manipulating genes in an organism, usually outside of the organism's normal reproductive process.

It often involves the isolation, manipulation and reintroduction of DNA into model organisms, usually to express a protein. The aim is introduce new genetic characteristics to an organism to increase its usefulness such as, increasing the yield of a crop species, introducing a novel characteristic, or producing a new protein or enzyme. Examples are the production of human insulin through the use of modified bacteria and the production of new types of mice like the OncoMouse, (cancer mouse) for research, through genetic redesign.

Since a protein is specified by a DNA segment or gene, future copies of that protein can be modified by changing the gene's underlying DNA. One way to do this is to isolate the DNA, cut it, and splice in a different DNA segment. Daniel Nathans and Hamilton Smith received the 1978 Nobel Prize in physiology or medicine for their isolation of restriction endonucleases, which are able to cut DNA at specific sites. Together with ligase, which can join together fragments of DNA, restriction enzymes formed the initial basis of recombinant DNA technology.

Naming

Genetic modification or genetic manipulation are neutral and possibly more technically correct terms for what is claimed, controversially, to be genetic engineering.

Many opponents of the use of the term 'genetic engineering' argue the operations of genes in combination with cell biochemistry are rather poorly understood and sometimes lead to unexpected side effects.

Reluctance to recognize this field as "engineering" has become popular in the anti-globalization movement and safe trade movement, and is also widely held by most Green parties, and the major parties of France and Germany, which have resisted any agricultural policy favoring genetically modified food. These groups tend to resist the label 'engineer' as applied to such genetic modification most strongly.

Defenders of the term genetic engineering argue that animal husbandry and crop breeding are also forms of genetic engineering that use artificial selection instead of modern genetic modification techniques. It is politics, they argue, not economics or science, that causes their work to be closely investigated, and for different standards to apply to it than to other fields of engineering. These scientists, however, do not object to the term 'genetic modification' as applied to what they do, although it is sometimes used to deny them the status of professionals serving society in an ethical manner, which is one implication of the term engineer.

Applications

The best known applications of genetic engineering are genetically modified organisms (GMOs).

There are potentially momentous biotechnology applications of GM, for example oral vaccines produced naturally in fruit at very low cost. This represents, however, a spread of genetic modification to medical purposes and opens an ethical door to other uses of the technology to directly modify human genomes.

These effects are often not traceable back to direct causes in the genome, but rather in the environment or interaction of proteins. The means by which 'genes' (in fact DNA strands that are assumed to have discrete effects) are detected and inserted are inexact, including such means as coating gold BBs with DNA to be inserted and literally firing it at strands of target DNA, which is guaranteed to cause insertions in at least some random locations, which can on rare occasion cause unplanned charecteristics.

Similar objections apply to protein engineering and molecular engineering for use as drugs. However, a single protein or a molecule is easier to examine for 'quality control' than a complete genome, and there are more limited claims made for the reliability of proteins and molecules, than for the genomes of whole organisms. While protein and molecule engineers often times acknowledge the requirement to test their products in a wide variety of environments to determine if they pose dangers to life, the position of many genetic engineers is that they do not need to do so, since the outputs of their work are 'substantially the same as' the original organism which was produced by the original genome(s).

An extreme ambition of some groups is human augmentation via genetics, eventually by artificial intelligence or molecular engineering. See also: transhumanism.

Genetic Engineering and Research

Although a there has been a tremendous revolution in the biological sciences in the past twenty years, there is still a great deal that remains to be discovered. The completion of the sequencing of the human genome, as well as the genomes of most agriculturally and scientifically important plants and animals, have increased the possibilities of genetic research immeasurably. Expedient and inexpensive access to comprehensive genetic data has become a reality, with billions of sequenced nucleotides already online and annotated. Now that the rapid sequencing of arbitrarily large genomes has become a simple, if not trivial affair, a much greater challenge will be elucidating function of the extraordinarily complex web of interacting proteins, dubbed the proteome, that constitutes and powers all living things. Genetic engineering has become the gold standard in protein research, and major research process has been made using a wide variety of techniques, including

- loss of function, such as in a knockout experiment, in which an organism is engineered to lack one or more genes. This allows the experimenter to analyze the defects caused by this mutation, and can be considerably useful in unearthing the function of a gene. It is used especially frequently in developmental biology. A knockout experiment involves the creation and manipulation of a DNA construct in vitro, which, in a simple knockout, consists of a copy of the desired gene which has been slightly altered such as to cripple its function. The construct is then taken up by embryonic stem cells, where the engineered copy of the gene replaces the organism's own gene. These stem cells are injected into blastocysts, which are implanted into surrogate mothers. Another method, useful in organisms such as drosophila, is to induce mutations in a large population and then screen the progeny for the desired mutation. A similar process can be used in both plants and prokaryotes.

- gain of function experiments, the logical counterpart of knockouts. These are sometimes performed in conjunction with knockout experiments to more finely establish the function of the desired gene. The process is much the same as that in knockout engineering, except that the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or attracting more frequent transcription.

- 'tracking' experiments, which seek to gain information about the localization and interaction of the desired protein. One way to do this is to replace the wild-type gene with a 'fusion' gene, which is a juxtaposition of the wild-type gene with a reporting element such as green fluorescent protein that will allow easy visualization of the products of the genetic modification. While this is a useful technique, the manipulation can destroy the function of the gene, creating secondary effects and possibly calling into question the results of the experiment. More sophisticated techniques are now in development that can track protein products without mitigating their function, such as the addition of small sequences which will serve as binding motifs to monoclonal antibodies.

Ethics

Genetic engineering proponents argue that the technology is harmless and necessary for food production to continue to match population growth. Others oppose this view, on the grounds that genetic modifications may have unforseen consequences, both in the initially modified organisms, and their environments. For example, certain strains of maize have been developed that are toxic to plant eating insects (see bt corn). However, when those strains cross-polinated with other varieties of wild and domestic maize, the relevant genes were passed on in unintended ways. This modified the very gene pool from which the maize was derived.

Anti-genetic-engineering groups propose that genetic releases such as this represent the opening of a Pandora's Box which may ultimately accelerate the collapse of the modern system of agriculture, decreasing rather than increasing the food supply. They say that with current recombinant technology there is no way to ensure that genetically modified organisms remain under control, and the use of this technology outside of secure laboratory environments carries grave risks for the future.

Many also fear that certain types of genetically engineered crops will enable the elimination of all biodiversity in the cropland; herbicide-tolerant crops will for example be treated with the relevant herbicide to the extent that there are no wild plants ('weeds') able to survive, and plants toxic to insects will mean insect-free crops. This could result in major declines in other wildlife (e.g. birds) which depend on weed seeds and/or insects for food resources. The recent (2003) farm scale studies in Britain found this to be the case with GM sugar beet and GM oilseed rape, but not with GM maize (though in the last instance, the non-GM comparison maize crop had also been treated with environmentally damaging pesticides subsequently (2004) withdrawn from use in the EU).

Proponents of current genetic techniques as applied to food plants cite the benefits that the technology can have, for example, in the harsh agricultural conditions of third world countries. They say that with modifications, existing crops would be able to thrive under the relatively hostile conditions providing much needed food to their people. While submitting that precautions should be made to ensure that any modified crops are contained, they say that their genetically engineered crops are not significantly different from those modified by nature or humans in the past, and by extension are not dangerous to other crops. The expansion of new croplands into areas currently too harsh to grow crops is also likely to have deleterious effects on the wildlife currently using these uncultivated areas. There is gene transfer between unicellular eukaryotes and prokaryotes. There have been no known genetic catastrophes as a result of this.

Economic and Political Effects

Many oppenents of current genetic engineering believe the increasing use of GM in major crops has caused a power shift in agriculture towards Biotechnology companies gaining far greater control over the production chain of crops and food then any previous industry, and over the farmers that use their products, as well.

Many propenents of current genetic engineering techniques believe it will bring higher yields and profitibility to many farmers, especially those in third world countries.

Genetic Engineering in Fiction

In Marvel Comics, the 31st century adventurers called the Guardians of the Galaxy are genegineered residents of Mercury, Jupiter, and Pluto.

In the Star Trek universe, the Breen, Species 8472, the Xindi, and the Federation use technology with organic components.

In the Star Wars universe, the Yuuzhan Vong are a race, who exclusively use organic technology and regard mechanical technology as heresy. Everything from starships to communications devices to weapons are bred and grown to suit their needs.

The film Gattaca had themes of genetic engineering.

See also:


  

From Wikipedia, the free encyclopedia. 
Modified by Geona