Download Genetic Engineering of Plants HW

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Genetic Engineering of Plants
By Mary Lynn Bushong
1
It seems like something out of a science fiction novel: scientists changing the DNA of plants grown for
food so that more could be grown with less. It sounds wonderful, but what are the long-term effects?
2
What is involved in making plants more efficient? There are two ways of doing this. The first is through
traditional plant breeding practices of selecting and cross-breeding plants of the same kind for certain traits. If
you were growing corn in Kansas, you might want to grow shorter corn plants that would be able to withstand
strong gusts of wind. You would select corn plants that were shorter for cross breeding and cross those until you
came up with a plant that was the height you wanted. This is an example of intentional plant breeding, assisted
by humans. This type of plant breeding can also occur naturally, without human intervention.
3
The second way of making plants more efficient is through genetic engineering. It is also called genetic
modification, gene splicing, or recombinant DNA technology. In plants, it involves the selection of desirable
genes and adding the gene or genes into the genetic code of a plant that you want to modify. Selected genes may
come from a closely related plant or a completely different plant. They may even come from a completely
different organism like a bacterium, a virus, or even an animal. It is not something that could naturally occur in
a plant.
4
Scientists can use several methods to join the new genetic material with the DNA of the plant they are
changing. Some types of bacteria can be used to insert the new genetic material into the plant's DNA through a
process called genetic recombination. Some plant viruses can be used to incorporate the new genetic
information into the plant's DNA. However, this method has several limitations. Also, there are several types of
new technology that allow the genetic material to be injected into the plant's DNA without the use of other
organisms. The gene gun is one of these. Microinjection is another.
5
Genetic engineering promises to do many great things to improve crop yields, boost farm profits, improve
plant hardiness, and even increase the nutritional value of crops. Still, many people are wary of this technology.
Critics argue that more research must be done before we allow genetically modified crops to flood our markets.
While there has been little evidence presented that these crops are harmful, there are a lot of questions that no
one knows how to answer about what effects genetic engineering may have on our environment, our food, and
our bodies years into the future.
6
How could genetic engineering cause problems in the environment? There are several ways. One concern is
that these genetically engineered crops have already contributed and will continue to contribute to a lack of
biodiversity. Long ago, there were many different varieties of crops grown all around the world. As large
commercial farms replaced backyard gardens, many of those crops began to vanish. In the United States it is
believed that 90% of the varieties of fruits and vegetables grown here in the past have become extinct. It is the
same throughout much of the rest of the world. Today, just twelve plant species provide about 75% of the
world's food.
7
Remember when we talked about traditional plant breeding? It mimics what can happen on its own in
nature. Well, this natural cross-breeding of plants is another way that genetic engineering could be a very bad
thing for the environment. One of the most popular methods of genetically engineering plants has been to insert
DNA that allows a plant to become resistant to the effects of weed killers. This allows farmers to plant their
crops and then spray their fields with weed killer to get rid of the weeds without harming their crops.
Unfortunately, this has created herbicide-resistant super-weeds. A worldwide report in 1978 counted only one
variety of herbicide-resistant weed. Today that number is closer to 200.
8
Yet another concern is how genetically modified crops will affect animals. Some evidence has already
shown us that they may be unintended victims. In Britain, the planting of a genetically modified sugar beet crop
that was resistant to herbicides led to a significant decrease in weeds. While farmers were pleased with this
result, the local skylark population was not. The seeds of those weeds were an important part of the diet of
skylarks. Scientists estimate that 80% of the skylark population had to find a different food source.
9
A study in the United States found that the caterpillars of Monarch butterflies also may be harmed by
genetically modified crops. In the study, caterpillars were fed "large amounts" of pollen from a genetically
modified variety of corn. The corn was modified to produce a toxin that served as a pesticide. In the study, 44%
of the caterpillars died after consuming the pollen. What effect will genetically modified crops have on bees?
They are the main pollinators for the majority of our crops. Are genetically modified crops responsible for the
declines that we are seeing in the bee population?
10
People also worry about what effects genetically modified crops will have on humans. Again, there are
many different ideas on how humans might be affected. Some genetically modified plants are created with
genes for antibiotic resistance. Some people are concerned that these genes may be passed along to other
species and that this type of genetic engineering will make worse the already growing problem of antibiotic
resistant disease causing bacteria. People also wonder if using bacteria and viruses to introduce new genetic
material into plants could lead to the creation of new types of bacteria or viruses that could cause disease.
11
Another concern that people have about genetically modified crops is how the food from these crops will
be different from traditional crops. Will a corn plant that has been engineered to produce a pesticide produce
that same toxin in the corn that is grown from it? If it does, what long term effects will the pesticide have on
people who eat it?
12
Allergens are another concern in genetically modified crops. Will inserting a single gene from a highly
allergenic food into other crops cause allergic reactions to the food grown by the genetically modified plant?
Experiments have already shown that this is certainly a possibility. How will consumers with allergies know
what foods they should avoid?
13
Genetically modified foods began to enter the food supply in 1994. Since then, the number of genetically
modified foods, or products containing genetically modified ingredients, available to consumers has increased
dramatically. Governments had to decide how to handle these new products. The United States decided to allow
these genetically modified foods to be sold without requiring a label to inform consumers that they were buying
a product that had been altered by genetic engineering. Many other countries in the world felt differently. As of
2013, 64 countries require genetically modified foods to be labeled as such.
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Many consumers are now demanding that the United States should require the labeling of genetically
modified foods as well. Those who are concerned about the genetically modified foods want to know what they
are eating and want people to be able to avoid genetically modified foods as they see fit. Those who are
adamantly opposed to genetically modified foods sometimes refer to them by another name -- "Frankenfoods."
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There is much that is still unknown about genetically engineered plants. It is possible that some of them
might hold the key to feeding a hungry world as the Earth's population grows larger. Even if that is the case,
many people believe that governments need to test for long-term safety before these engineered plants are
allowed out of the laboratory. It can sometimes take years of exposure for problems to turn up. Those cautious
of genetic engineering in plants believe these studies should test long-term effects before the genetically
engineered genie is all the way out of the bottle.
1. How can people make plants more efficient?
Selective breeding
Genetic engineering
Both a and b
There is no way people can affect plants.
2. Scientists use _______ to carry new genetic
material to an existing DNA strand.
Microinjection
A gene gun
Bacteria or viruses
All of the above
3. What negative effect(s) are some people worried 4. How does conventional plant breeding differ from
might come from using bacteria or viruses to carry
genetic engineering?
genes for genetic recombination?
5. What is the purpose or goal for genetically
engineering plants?
Making plants more efficient so that more
food could be grown with less
Seeing how people can affect the ways that
food is grown
Using bacteria and viruses in a helpful way
Seeing how far people can push the
boundaries of nature
6. What is one of the possible dangers of having
unlabeled genetically engineered food?
Some people call genetically modified foods “Frankenfoods.” Is this a good nickname?
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