Genetic Engineering K-12 Experiments
Biotechnology vs. Genetic Engineering
When Hungarian engineer Karl Ereky coined the word biotechnology in 1919 to describe the production of goods from raw materials with the aid of living organisms, he was describing techniques that had been employed by human beings for centuries. This includes techniques such as selective breeding, fermentation, hybridization, phyto-pharmacology, vaccination or the use of biomass for energy production.
However, the term biotechnology has evolved to include modern techniques with new applications, to what is now known as modern biotechnology. Modern biotechnology encompasses techniques such as genetic engineering (which is the direct intervention on the genetic makeup of an organisms usually by introducing foreign DNA into its gene pool by means that would not occur naturally), tissue culture and others. These modern techniques also take considerably less time to achieve the desirable changes in living organisms and carry greater precision than traditional techniques.
In short, genetic engineering is a specific subset as a part of the more general subject of biotechnology.
Genetic Engineering
An iconic image of genetic engineering; this 1986 "autoluminograph" of a glowing transgenic tobacco plant bearing the luciferase gene of the firefly strikingly demonstrates the power and potential of genetic manipulation.
Genetic engineering, genetic modification (GM), and the now-deprecated gene splicing are terms for the process of manipulating genes, usually outside the organism's normal reproductive process.
It often involves the isolation, manipulation and reintroduction of DNA into cells or model organisms, usually to express a protein.
The aim is to introduce new characteristics such as making a crop
resistant to an herbicide, introducing a novel trait, or producing a
new protein or enzyme. Examples include the production of human insulin through the use of modified bacteria, the production of erythropoietin in Chinese Hamster Ovary cells, and the production of new types of experimental mice such as the OncoMouse (cancer mouse) for research, through genetic redesign.
Since a protein is specified by a segment of DNA called a gene,
future versions of that protein can be modified by changing the gene's
underlying DNA. One way to do this is to isolate the piece of DNA
containing the gene, precisely cut the gene out, and then reintroduce
(splice) the gene into 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 fragments of DNA together, restriction enzymes formed the initial basis of recombinant DNA technology.
Terminology
"Transgenic organism" is now the preferred term for genetically
modified organisms with extra-genome (foreign genetic) information, as
opposed to "genetically engineered" or "genetically modified" organisms
(which may refer to changes made within the genome such as
amplification or deletion of genes).
Applications
The first Genetically Engineered drug was human insulin approved by the USA's FDA in 1982 [1].
Another early application of GE was to create human growth hormone as
replacement for a drug that was previously extracted from human
cadavers. In 1986 the FDA approved the first genetically engineered
vaccine for humans, for hepatitis B[2]. Since these early uses of the technology in medicine the use of the GE has expanded to supply many drugs and vaccines.
One of the best known applications of genetic engineering is that of the creation of genetically modified organisms (GMOs).
There are potentially momentous biotechnological applications of GM, for example oral vaccines produced naturally in fruit, at very low cost.
A radical ambition of some groups is human enhancement via genetics, eventually by molecular engineering. See also: transhumanism.
DNA sequencing
is a technique which is used to identify each base in DNA. Although the
costs of DNA sequencing has dropped dramatically, the NIH estimates it
costs at least $10 million to sequence 3 billion base pairs [3] - the size of the whole human genome.
Genetic engineering and research
Although 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, has 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 progress 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 the activity of
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 (fruit fly), 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
(GFP) 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
Proponents of genetic engineering argue that the technology is safe, and that it is necessary in order to maintain food production that will continue to match population growth and help feed millions in Third World
countries more effectively. Others argue that there is more than enough
food in the world and that the problem is food distribution, not
production, so people should not be forced to eat food that may carry
some degree of risk.
Others oppose genetic engineering on the grounds that genetic
modifications might have unforeseen 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).
It has been alleged those strains cross-pollinated with other varieties
of wild and domestic maize and passed on these genes with a putative
impact on Maize biodiversity.[1]
Subsequent to the publication of these results, several scientists
pointed out that the conclusions were based on experiments with design
flaws. It is well known that the results from the Polymerase Chain Reaction
method of analysing DNA can often be confounded by sample contamination
and experimental artifacts. Appropriate controls can be included in
experiments to eliminate these as a possible explanation of the results
- however these controls were not includeed in the methods used by Quist
and Chapela.[2] After this criticism Nature,
the scientific journal where this data was originally published
"concluded that the evidence available is not sufficient to justify the
publication of the original paper".[3]
More recent attempts to replicate the original studies have concluded
that genetically modified corn is absent from southern Mexico in 2003
and 2004 [4] Also in dispute is the impact on biodiversity of the introgression of transgenes into wild populations [5].
Unless a transgene offers a massive selective advantage in a wild
population, a transgene that enters such a population will be
maintained at a low gene frequency. In such situations it can be argued
that such an introgression actually increases biodiversity rather than lowers it.
Activists opposed to genetic engineering say that with current recombinant technology there is no way to ensure that genetically modified organisms
will remain under control, and the use of this technology outside
secure laboratory environments carries unacceptable risks for the
future.
Some fear that certain types of genetically engineered crops will further reduce 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 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 the UK found this to be the case with GM sugar beet and GM rapeseed,
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 Africa.
They say that with modifications, existing crops would be able to
thrive under the relatively hostile conditions providing much needed
food to their people. Proponents also cite golden rice
and golden rice 2, genetically engineered rice varieties (still under
development) that contain elevated vitamin A levels. There is hope that
this rice may alleviate vitamin A deficiency that contributes to the
death of millions and permanent blindness of 500,000 annually.
Proponents say that genetically-engineered crops are not
significantly different from those modified by nature or humans in the
past, and are as safe or even safer than such methods. There is gene
transfer between unicellular eukaryotes and prokaryotes. There have been no known genetic catastrophes as a result of this. They 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 those
applied to other forms of agricultural technology.
Proponents also note that species or genera barriers have been
crossed in nature in the past. An oft-cited example is today's modern
red wheat variety, which is the result of two natural crossings made
long ago. It is made up of three groups of seven chromosomes. Each of
those three groups came from a different wild wheat grass. First, a
cross between two of the grasses occurred, creating the durum wheats, which were the commercial grains of the first civilizations up through the Roman Republic.
Then a cross occurred between that 14-chromosome durum wheat and
another wild grass to create what became modern red wheat at the time
of the Roman Empire.
Economic and political effects
- Many opponents of current genetic engineering believe the
increasing use of GM in major crops has caused a power shift in
agriculture towards Biotechnology companies gaining excessive control
over the production chain of crops and food, and over the farmers that
use their products, as well.
- Many proponents of current genetic engineering techniques believe
it will lower pesticide usage and has brought higher yields and
profitability to many farmers, including those developing nations. A
few GM licenses allow farmers in less economically developed countries
to save seeds for next year's planting.
- In August 2002, Zambia cut off the flow of Genetically Modified Food (mostly maize) from UN's World Food Programme.
Although there were claims that this left a famine-stricken population
without food aid, the U.N. program succeeded in replacing the rejected
grain with other sources, including some foods purchased locally with
European cash donations. In rejecting the maize, Zambians cited the
"Precautionary Principle" and also the desire to protect future
possibilities of grain exports to Europe.
- In December 2005 the Zambian government changed its mind in the face of further famine and allowed the importation of GM maize [6]
- In April 2004 Hugo Chávez announced a total ban on genetically modified seeds in Venezuela.
- In January 2005, the Hungarian
government announced a ban on importing and planting of genetic
modified maize seeds, although these were authorized by the EU. [7]
See also
References
- ↑ Quist D and Chapela IH (2001). "Transgenic DNA introgressed into traditional maize landraces in Oaxaca, Mexico". Nature 414: 541-543. DOI:10.1038/35107068.
- ↑ Christou,
Paul (2002). "No Credible Scientific Evidence is Presented to Support
Claims that Transgenic DNA was Introgressed into Traditional Maize
Landraces in Oaxaca, Mexico". Transgenic Research 11 (1): 3-5. DOI:10.1023/A:1013903300469.
- ↑ (2002). "Biodiversity (Communications arising): Suspect evidence of transgenic contamination". Nature 416: 600-601. DOI:10.1038/nature738.
External links
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia Encyclopedia article "Genetic Engineering"
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