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Greg Thor
Biology 1010
Luz Teicher
10-10-10
Genetic Engineering in Plants and Animals
Biological organisms that have been genetically engineered are those that have
either been given new traits that they otherwise would not have had, or they are those that
have had existing traits modified. There are a few different processes that can be used to
achieve this, but what are the potential uses of this technology? What also are the risks
involved in altering genes? Some say that scientists have gone too far and their
experiments are ethically wrong and potentially dangerous.
The technique of engineering a gene involves “... researchers to take
certain genes from a source organism and put those genes into another plant or animal.
Similar techniques can be used to regulate the amount of protein produced by a gene.
These techniques are called Genetic Engineering” (NCSU). Herbert Boyer and Stanley
Cohen are thought by many in the scientific
community to be the fathers of genetic
engineering. They met in Hawaii at a
conference on bacterial plasmids and after
adjourned to a local deli where “Over hot
pastrami and corned beef sandwiches,
Herbert Boyer < http://www.pbs.org
/wgbh/theymadeamerica/whomade/boyer_hi.html>
Herbert Boyer and Stanley Cohen opened the
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door to genetic engineering and laid the foundations for gene therapy and the
biotechnology industry”(MIT).
Cohen had been doing work on individually cloning specific genes in antibiotic
carrying plasmids while Boyer was figuring out that he could cut DNA using restriction
enzymes. The two melded their work into one process, using Boyer’s restriction enzyme
they cut the plasmid of an Ecoli bacterium and using DNA ligase sealed in a piece of
foreign DNA into the bacterial plasmid. When the bacteria
reproduced it passed the newly genetic inserted trait to its offspring,
naturally replicating the desired DNA. Stanley Cohen says “Boyer
and I didn't set out to invent genetic engineering. Our invention came
from efforts to understand basic biological phenomena and the
realization that our findings had important practical applications”
(MIT).
Stanley Cohen < http://www.picsearc
h.com/pictures/celebrities/nobel%20p
rize%20winners/medicine/winner…>
Scientists can enhance existing genes in organisms to amplify desired traits or
knock them out entirely to mask a trait. There are methods that incorporate genes from
one organism into a completely different organism.” Foreign DNA is introduced into the
animal, using recombinant DNA technology, and then must be transmitted through the
germ line so that every cell, including germ cells, of the animal contain the same
modified genetic material. This process produces a transgenic organism embryonic stem
cell-mediated gene transfer” (Buy). One practical application of this is gene pharming. In
this process animals such as goats are used to produce pharmaceutical substances such as
HGH (Human Growth Hormone) and insulin. The conceptual possibilities are virtually
endless. One good example is the Oncomouse, “with its increased susceptibility to tumor
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development enables results for carcinogenicity studies to be obtained within a shorter
time-frame, thus reducing the course of tumor development in experimentally affected
Simple mathematical equation for how to get spider silk< http://www
uwyo.edu/news/webclips/showrelease.asp?webclipid=3521>
animals” (Buy).
Another
example is the
spider goat
which is a goat
that has been
implanted with
the gene that
controls the production of spider silk. Spider silk is one of the toughest fibers known to
man. Currently it is synthesized using DNA from a golden orb weaver, but “Darwin’s
bark spider makes the largest webs in the world, spinning silk that is 10 times stronger
than Kevlar” (Boyle); but the bark spider has yet to be successfully implanted to a goat.
Transgenic organisms can be formed one of three ways: DNA microinjection,
embryonic stem cell-mediated gene transfer, and retrovirus-mediated gene transfer. In
DNA microinjection a chosen gene construct has been microinjected into the pronucleus
of a fertilized ovum. This is not guaranteed to produce an F1 generation that carries the
gene, in all these methods it is actually more likely not to. Although “a major advantage
of this method is its applicability to a wide variety of species” (Buy). Embryonic stem
cell-mediated gene transfer is a technique that adds desired DNA to a stem cell then adds
those cells to the embryo of an animal at the blastocyst stage of development. Retrovirusmediated gene transfer is similar, where as the desired DNA is added to a virus or a
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plasmid then naturally replicated. The F1 generation is said to be chimeric, not all of the
offspring possess the gene.” When the transgene has integrated into the germ cells, the
so-called germ line chimeras are then inbred for 10 to 20 generations until homozygous
transgenic animals are obtained and the transgene is present in every cell” (Buy). Then
the organism can be studied with a clearly present genome.
Kary Mullis< http://www.karymullis.com/
biography.shtml>
The replication of DNA has
taken radical steps forward, and can now
be rapidly synthesized fairly
inexpensively. The most frequently used
method is recombinant DNA using the
polymerase chain reaction(PCR). This method was conceptualized by Kary Mullis in
1983. In the process of PCR the sample is first heated so the DNA denatures, or separates
into two pieces of single-stranded DNA. Then an enzyme called polymerase synthesizes
and builds two new strands of DNA from excess parts using the original strands as a
pattern. Restriction enzymes decide when and where to cut the strands of DNA making
the copies precise replicas. It takes little time, about an hour, before the self-replicating
process yields new strands in the millions.
With the advances in PCR and transgenic organisms scientists have had a tidal
wave of new ideas concerning gene alteration and manipulation. They can now breed
plants with immunities to natural predators as well as animals with characteristics from
two species, but what exactly are some common types of altered organisms being
produced? One of the most widely modified and controversial crops are corn. World wide
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Genetically modified corn < http://news.discovery.com
/earth/is-genetically-modified-corn-toxic.html>
Genetically Modified (GM) corn is
grown; in the U.S. almost 50% of the
corn grown is a GM product (Mader).
The corn is not approved for human
consumption, but is used as feed for
livestock. In Italy there is controversy
over the use of the GM crop
MONO810 corn and the government
requires special approval before planting them even though “Both the United States Food
and Drug Administration and the European Food Safety Agency say that there is no
scientific evidence that eating MON810 corn is dangerous. But there is greater
disagreement on how genetically modified plants affect ecosystems and whether
traditional and genetically modified crops can be kept apart to avoid what organic
farmers call “contamination” of traditional crops by modified plants or genes”
(Rosenthal). Possible contamination could lead to crossbred MON810 corn eventually
overtaking the organically occurring corn species.
In the agricultural field there is much interest in the positive side of Genetically
Modified Organisms (GMO) amongst researchers and farmers as well as the potential
downfalls. Zachary Lippman is a scientist working in the development of tomato plants.
“He produced a strain of hyper-productive tomato seeds through his manipulation of a
“flower power gene” known as S.F.T. (single flower truss), the “command gene” that
tells plants when and how many flowers to generate. He is fixated on the potential of
plant genetics to radically improve the yield not only of plum tomatoes but of boutique
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melons and mass-produced crops like soybeans” (Finn). Lippman further refined his
work and the result is a tomato plant that produces more than 150% the normal fruit
yield. One of the biggest debates though is whether or not engineered products are safe to
consume. The Food and Drug Administration has been examining the potential effects of
GMO on the ecosystem since the 70’s, and has no definite decision on the safety of
GMO. Many ideas have been presented and rejected” Then the gene for chymosin
Synthesis of chymosin <http://dwb4.unl.edu/Chem/CHEM869N/CHEM869
NLinks/www.ncbe.reading.ac.uk/NCBE/GMFOOD/IMAGES/Chymosin.gif
production was
incorporated into the DNA
of both bacteria and
yeasts. Pure chymosin can
now be made. The enzyme
is identical to that
produced in the calf and
the process itself adds no
contaminants. The FDA evaluated the safety of the process and the product itself in 1990
and ruled that the enzyme preparation was safe for human consumption” (NCSU). Today
the majority of cheese in the U.S. has had a genetically engineered chymosin enzyme as
an ingredient, and there have been no noticeable side effects from the consumption of the
enzyme by humans.
How do we really know that these products are safe and how do we test
them? The truth is that without a model built over a larger span of time there is no way to
tell other than by the little amount of data that is available, although methods similar to
the genetic modification process are used to test for dangers.” Advances in scientific
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fields such as toxicology and immunology put science in a better position to evaluate and
recognize potential hazards and assure product safety of any new foods derived from
biotechnology. As with any food or food process, safety remains paramount. It is
<http://www.toonpool.com/cartoons/Gen
seriously considered before any product is placed into the food production or distribution
etic%20Farming_33646http://www.goog
le.com/imgres?imgurl=http://www.toonp
chain” (NCSU). That means that no MON810
ool.com/user/856/files/genetic_farminghtt
corn will be on your plate any time soon.
p://www.google.com/imgres?imgurl=http://www.toonpool.co
m/user/856/files/genetic_farming
Animals are subject to the same scrutiny
as plants when introduction to the environment is
concerned “Currently, the FDA regulates
transgenic animals under the New Animal Drug
Approval Process. Transgenic animals themselves are considered a drug because they
have been genetically engineered. But the agency is still working to craft its policies in
this emerging field, says Stephen Sundlof, director of the FDA's Center for Veterinary
Medicine” (Weise).
The consumption of these animals is out of the question for now, but the practical
applications for their products are limitless. Insect resistant corn however controversial
has real merit as a functional solution to a problem, and is seemingly easier and cheaper
than spraying thousands of acres with pesticide. The use of transgenic goats is an
amazing source for numerous medical products that can be rapidly synthesized at a low
cost. The usage of genetics has even been used to give us a better look at history. Using
recombant DNA and fossilized remains scientists have started a new field called
paleobiology. They can examine DNA from extinct species as well as identify remains of
Russian royalty that died in war. With such a plethora of applications the science of
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genetic engineering has to existing disciplines it has brought about remarkable
revelations already and still has many more contributions to make in the future.
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Works Cited
Boyle, Rebecca. “How Modified Worms and Goats Can Mass-Produce Nature's
Toughest Fiber”. Popular Science.Oct.06.2010. Oct.18.2010.< http://www.popsci
.com/science/article/2010-10/fabrics-spider-silk-get-closer-reality>
Buy, Mary. “Transgenic Animals”. Canadian Council on Animal Care. Oct. 24. 2010.<
http://people.ucalgary.ca/~browder/transgenic.html>
Finn, Robin. “From Super Seeds to Mutant Tomatoes”. New York Times. Aug. 20.
2010. Oct. 18. 2010. < http://www.nytimes.com/2010/08/22/nyregion/22tomato.html>
Mader, Sylvia. Concepts of Biology. McGraw-Hill co. 2009. Oct.18. 2010. pg 230
MIT(Massachusetts Institute of Technology). 1996 Lemelson-MIT Prize Winners.
Oct.18. 2010. < http://web.mit.edu/invent/a-winners/a-boyercohen.html>
North Carolina Cooperative Extension. “Genetic Engineering of Food, Feed, and
Fiber: Understanding Genetic Engineering”. Oct. 15. 2010.<http://www.ces.ncsu.edu
/resources/crops/ag546-1/>
Rosenthal, Elisabeth. “In the Fields of Italy, a Conflict Over Corn”. New York
Times.Aug. 23, 2010. Oct. 18. 2010. <http://www.nytimes.com /2010/08/24 /world/
europe/24modify.html?ref=monsanto_company>
Weise, Elizabeth. “Scientists Fear 'Uncertainty' Of Genetically Altered Animals” USA
Today, Aug. 21. 2002. Oct. 18. 2010. <http://www.geneticengineering.net/ScientistsFear
GeneticallyAlteredAnimals.htm>