Transcript Transgenic Corn

Transgenic plants and genetically modified
organisms are both created by selecting a
specific gene or genes from one species and
placing it into the DNA of another species.
This results in a phenotypic change in the
species that the gene(s) was implanted into.
There are two methods for introducing a
foreign gene into an organism. The first
method is using a bacterium as a vector, and
the second is using a gene gun, which is
sometimes referred to as biolistics.
Key Scientists
In 1981, Eugene Nester and Mary
Dell Chilton came up with a way in
which foreign genes could be
Eugene Nester
introduced into plant cells creating
transgenic plants. They used the Ti
plasmid (tumor inducing plasmid) that
is carried by soil bacteria called
Agrobacterium tumefaciens.
Mary Dell Chilton
How does a vector create transgenic plants?
The Agrobacterium tumefacien bacteria is a vector, which means it enables the
transportation of foreign genes into plants. This bacteria contains a tumor inducing
(Ti) plasmid. The T region of the plasmid becomes incorporated in the plant cell.
1. A foreign gene is inserted into the T region of
a plasmid in a bacterium.
2. The bacterium gains access to a plant
through a wound such as a torn leaf or
broken branch.
3. The vector enters the nucleus of a plant cell.
4. The T region becomes incorporated into a
chromosome in the plant cell.
5. The foreign gene is now part of the plant’s
DNA, changing the plant’s phenotype.
Agrobacterium tumefaciens cells
attached to a plant cell.
This bacteria can only inflict organisms such as beans, peas and potatoes.
How does a gene gun work?
1. Tungsten or gold particles are coated with DNA.
2. The particles are accelerated in a partial
vacuum.
3. The target tissue is placed in the path of the
accelerating particle.
4. The metal atom passes right through the cell,
but the DNA is left inside the cell, becoming a
part of the organism’s original DNA.
5. A marker gene is used so scientists can be sure
that the gene entered the cell, and stayed inside.
6. The new genetically modified cell grows and
replicates
Gene gun
Gene guns are used to place foreign genes into wheat, corn and rice.
Benefits of Transgenic Plants
 Enhance, taste, quality, and nutrition
 Improved resistance to disease, pests, and herbicides
 Reduce maturation time (grow faster)
 Increase shelf life
 Weather tolerance (temperature, drought, etc.)
 Pharmaceuticals: researchers are working on
developing edible vaccines in tomatoes and potatoes
 Decrease Pollution: Some genetically modified plants
and poplar trees were designed to clean up heavy metal
pollution from contaminated soil
Drawbacks of Transgenic Plants
 The process of engineering genetically modified
plants takes a very long time and is expensive
 Possibility of causing new allergic reactions
 Long term effects on human health are unknown
 Genes could transfer to untargeted species such as
weeds, making them resistant to herbicides and pests
 Negative impact on ecosystems: the pollen from
transgenic corn killed many monarch caterpillars
because the pollen was carried by the wind onto
milkweed, which is their food source.
Golden Rice
 Golden rice was genetically
modified to have high levels of
beta carotene, which is used by
the body to synthesize vitamin A.
 The rice contains genes from a
daffodil, pea, bacterium and a
virus.
 Many people don’t get enough
vitamin A from their diet and if they
have a severe enough deficiency
they can go blind.
White Rice and Golden Rice
Transgenic Corn
Transgenic corn was created
to be pest resistant,
specifically to the corn borer
“Ostrinia nubilalis”. This corn
would increase the farmer’s
corn yield, and save them
money because they wouldn’t
have to throw away corn that
was destroyed by pests.
Left:
Ostrinia
nubilalis
Transgenic corn
is on the left of
each picture
and regular
corn is on the
right.
The Favr Savr Tomato
The Endless Summer Tomato
One of the first approved
modifications to an organism was
a tomato, in which the gene that
causes the tomato to ripen was
minimized in order to give the
tomato a longer shelf life.
Scientists found, copied, and rebuilt a
gene that lets tomatoes stay on the
vine longer without softening and
spoiling. This means that they can
develop more sugars and acids,
which gives them more flavour.
Genetically Engineered Insulin producing Bacteria
Insulin is needed in humans to control the level of
sugars in the blood.
The gene for insulin production in humans has been
isolated and inserted into bacterial cells. Theses
cells then transcribe and translate the gene into the
protein insulin. The bacteria then replicate, creating
even more bacteria to produce insulin.
This was a significant discovery because previously
people with diabetes relied on insulin from other
animals, such as pigs. However, some people were
allergic to the insulin produced by pigs.
Alba: The Fluorescent Rabbit
Though mainly used for
genetically modifying plants
there have been cases where
this technology has been used to
modify animals as well.
An example of this is the
infamous rabbit Alba, in which a
gene from a jellyfish was
inserted into the DNA of a rabbit
so it would glow green when
exposed to ultra violet light. Alba
was created solely for the
purpose of art.
An Aequorea victoria jellyfish
Alba the fluorescent bunny
Spider Goats
Spider silk is the strongest natural fiber known
to science. It is tougher than Kevlar, stretches
better than nylon, and is five times stronger
than steel (weight for weight).
A spider gene was incorporated into the DNA
of a goat embryo. The gene codes for the
synthesis of a protein found in spider webs.
The gene causes the goat to produce this web
protein in its mammary glands, and it comes
out in its milk. Scientists then take the protein
and form it into thin strands. The farm that this
is occurring at is located outside of Montreal,
Canada. Scientists have only managed to
make strands of web about 1/10 as strong as a
spider can make, but are working on making
them stronger. The spider silk could potentially
be used for sutures, artificial ligaments and
tendons, or bullet proof vests.
Other examples of genetically modified animals…
Salmon have been bio-engineered to grow twice as fast
as they would normally. Salmon usually only produce a
growth hormone at certain times of the year. The engineers
were able to keep the hormone active by using another
gene from an eel-like fish called an ocean pout that acts like
an on switch for the hormone. The switch is kept on all the
time, so the salmon grows much faster.

Dairy cows are being bio-engineered to have a 10%
increase in milk production.
 Cattle are being genetically modified so that they are
resistant to mad cow disease (currently being developed).
Facts:
 The majority of transgenic crops grown are
herbicide and insect resistant soybeans, corn,
cotton, canola, and alfalfa.
 The United States grows 53% of the transgenic
crops in the world, while Canada only grows 6%.
 Since 1994 only about 40 genetically modified foods
have been approved in Canada
 Labeling genetically modified plants isn’t mandatory.
However, some companies choose to label their
products anyways.
Conclusion
Although genetically modified foods have benefits,
there are still risks, and we must be cautious.
Genetically modified organisms still remain a
controversial issue, and will probably continue to be
debated for a long time to come.
We must take into account the health,
environmental, and economic effects that these
organisms can result in.
Who knows, maybe in the future we will be creating
genetically modified humans!!!
QUIZ
1. True or false? The gene gun technique of
introducing foreign genes into an organism is
also known as biolistics.
Answer: TRUE
2. In 1981, who developed the Ti plasmid method of
introducing a foreign gene into plants?
A. Clinton Marsh and Evelyn Nelson
B. Mary Chilton and Eugene Nester
C. James Watson and Francis Crick
D. Edward Smith and Margaret Clarke
Answer: B
3.
True or False? Golden rice was
bio-engineered to contain high
amounts of vitamin A.
Answer: FALSE It was bio-engineered
to have high amounts of ß-catotene,
which is made into vitatim A molecules
by your body.
4. Which of the following is not a benefit of
genetically modified organisms?
A. Prolonged shelf life of vegetables.
B. Higher tolerance of weather.
C. Interactions with other plants or wildlife.
D. Resistance to disease, pests, and herbicides.
Answer: C
Works Cited
“Bioengineered Tomatoes Taste Great.” The CBS Interactive Business Network. 2010. Online. 28 Nov. 2010.
<http://findarticles.com/p/articles/mi_m3741/is_n7_v43/ai_17294707/>
Di Giuseppe, Maurice, et al. Biology 12. Toronto: Nelson, 2003. Print.
“Genetically Modified Foods and Organisms .” Human Genome Project Information. 2008. Online. 27 Nov. 2010.
<http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml>
“Genetically Modified Salmon Hearings Begin.” CBC News. 2010. Online. 30 Nov. 2010.
<http://www.cbc.ca/canada/prince-edward-island/story/2010/09/20/con-gm-salmon-hearing.html>
“Mixing Spiders with Goats to make bullet proof vests.” You Tube. 2010. Online Video clip. 1 Dec. 2010.
<http://www.youtube.com/watch?v=q0WCjX8jUE4>