Genetically Modified Foods Project: Introduction
Overview:
Genetically modified organisms, or GMOs, are foods that have been genetically altered by scientists. Also known as transgenic organisms, or genetically engineered organisms, scientists have designed GMOs to incorporate useful qualities into plants, animals, or bacteria. One example is a corn plant that has been genetically altered to include a gene from bacteria which enabled the corn plant to be resistant to the common insect pests. The benefit of this is that the farmer doesn’t have to use as many pesticides on their plants. A drawback is that the farmer has to buy this special seed from the company year after year.
Background: Humans have been modifying plants for a very long time. Farmers use different techniques to modify plants. One example is cross pollination, in which the pollen of one plant is exposed to a different plant by using tools such as a small paint brush. These modifications only happen if the two plants are similar enough to combine. Since this process involves sexual reproduction, one cannot control exactly which genes will be expressed in the plant, so you may get both desirable and undesirable results.
Benefits of GM: Genes that influence particular traits like size, nutritional value, and durability are often isolated and put into crops. Genetically modified food can have increased nutritional value, increased size and flavor, tolerance of the plant to bad weather and resistance to herbicides. Often these genes come from other plant or animal species. For example, Golden Rice is a GM crop enriched with extra vitamin A. Many people in third world countries survive on a diet that’s mainly rice, and if Golden Rice was available worldwide it would help combat global malnutrition. Bt corn produces its own insecticides so the farmer does not have to use as many pesticides. Flavr Savr tomatoes were designed to ripen and rot more slowly to increase shelf life in supermarkets. Most recently, scientists created a type of genetically modified salmon that grow much larger than natural salmon do.
How GM food is made: How do scientists insert a particular gene into an organism? Scientists start with the genetic material of the organism that naturally contains the gene of interest. Using a special kind of cutting protein called a restriction enzyme, the specific gene is removed. Copies of the gene are made by inserting it into the DNA of dividing bacteria. Every time the bacteria divide, the DNA, along with the inserted gene, is replicated. Finally, the scientists must insert the gene into the recipient. This can be done using other bacteria that infect plants and have the ability to transfer DNA into the plant. One such bacterium is A.tumefaciens. This bacterium has naturally developed a way of inserting DNA into the plant’s nuclear DNA, so the scientists have used this natural process to insert artificial genes.
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One of the major producers of GM seed in the United States is a company called Monsanto. Monsanto is not the only company making transgenic seeds for GM crops, but it is the largest and most visiblecompany.
Question: List a few traits that would be desirable in a crop such as corn. How quickly would it take to develop a crop with this trait if only natural selection was used? What if the crop was genetically engineered?
Risks of GM Food - Although GMOs offer ways to fight malnutrition, alleviate farming costs, and
decrease the amount of spoiled food, not a lot of research has been done on some of the impacts ofgenetically modified food.
The Farmer
Since GM crops are 'invented' and produced by companies, these companies can patent them, or own the rights to their production. This presents two problems for farmers. Farmers must purchase new seed every season, which is costly, decreasing the amount they save due to the genetic modification (as in money saved on pesticides). Secondly, since the genetic code of the GM plant is patented, crosspollination is illegal and is considered patent infringement. As you can guess, this is tricky for the farmer and forces him to use what are called 'refuge crops’ to isolate the GM fields.
Another problem for farmers involves environmental impacts. The apple tree created by a scientist may
defend itself against the caterpillar pests very well. It may also, however, kill other insects that scientistsdid not intend to affect such as ladybugs and lacewings. Such negative impacts on the environment must be taken into consideration. The caterpillars originally targeted by a scientist's toxin may evolve
resistance and once again threaten his harvest. In this way, genetic modification can foster ’super pests.'
The Consumer
GM crops are distributed everywhere as fresh food and ingredients in processed foods. Although the foreign DNA and proteins that exist in a GM plant are no different from their naturally occurring equivalents, our bodies may not be accustomed to digesting the particular food makeup that a GM food presents us with. One example is a crop called Bt corn. Bt is a very common spray-on insecticide. Bt corn innately produces a poisonous chemical, protecting itself from a particular kind of caterpillar without the need for the farmer to spray pesticides. Bt corn produces much more of the insecticide than is usually sprayed and contains it throughout the plant rather than just on the outside. Washing normal corn would remove the Bt toxin; however, with Bt corn the toxin cannot be removed. Such modifications could introduce new allergens and harmful chemicals into the foods we eat daily.
Question: Think your food is GM free? Take a closer look!
The United States is one of the only countries that does not mandate labeling of genetically modified food. Check your food labels for any of the following ingredients (see below). Make a list of the food products. They may or may not be genetically modified.
Corn: corn oil, corn syrup, high fructose corn syrup, corn starch, corn meal
Soy: soy protein, soy lecithin, soy oil, soy sauce, soy isolates
Canola: canola oil
Cotton: cottonseed oil
In this experiment, we are going to look for genetically modified soy, called herbicide-tolerant or Ht soy.
Ht soy is resistant to a particular set of herbicides that work in a common way. When this type of herbicide is applied to a plant the chemical interferes with the plant’s ability to photosynthesize (make energy from sunlight and CO2 gas). Without photosynthesis a plant dies.
Ht soy was developed by the company Monsanto by the inserting a gene from a soil bacterium, Streptomyces viridochromogenes, into soy. The pat gene contains the instructions for making a specific kind of enzyme called the PAT enzyme. The PAT enzyme stops the herbicide from impeding photosynthesis. Ht soy is resistant to the effects of the herbicide (Bayer CropScience, ILSI). In this way, farmers with Ht soy can apply herbicides to fields to kill the weeds without worrying about their crop.
According to the USDA more than 90% of the acres of soy planted in the United States are Ht soy. We can test for Ht soy in common food products by looking specifically for the gene that was inserted to make it herbicide tolerant.
How do we do this?In italics is why we’re doing each step.....
1. Obtain a sample of a soy product. Soy is a commonly modified plant product.
2. Add a lysis buffer to dissolve the cell walls. So we can get to the DNA.
3. Isolate the DNA from everything else using ethanol precipitation. DNA is not soluble in ethanol.
4. Resuspend the DNA in water. It’s easier to work with a solution than a solid.
5. Add small sequences of DNA called primers to the DNA. We can select for the part of DNA that is usually modified by scientists using primers.
6. Add enzymes to the sample. The enzymes help make the reaction happen.
7. Add a mix of nucleotides to the sample. These extra nucleotides will help make new DNA.
8. Put the sample into a thermal cycler overnight. The thermal cycler can “cycle” between differenttemperatures to 1. Break the DNA apart, 2. Activate the enzyme to start copying and 3. Allow
nucleotides to combine with the single stranded DNA. Many copies of DNA are made.
9. Take the sample and put it into a high temperature environment. This breaks the DNA into two single strands.
10. Add a probe to the sample. This will enable us to "see” whether our DNA sample is natural or genetically modified.
11. Pipet the sample and red colored beads onto a biosensor. The beads will attach to the probes on
the DNA, and will create either one line or two lines on the biosensor.
12. Put the biosensor into a running buffer. The running buffer will carry the reagents up the biosensor. The reaction between the beads, probe and the DNA sample happens on the biosensor itself.
GM Information Sites
This is an overview provided by the US Government.
This website is run by Monsanto, a major manufacturer of GM seed.
This website is run by a non-profit called the non GMO group.