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Team:UCSF/ALHS Project
From 2013.igem.org
Teaching Synthetic Biology to High School Students: A common misunderstanding held by proponents of organic food, is that once genetically modified organisms (GMOs) are incorporated into our food supply, they will become undetectable, and cannot be differentiated from other foods. To educate their peers, students in the Biotechnology Academy at Abraham Lincoln High School in San Francisco offered to teach their fellow students in the school’s ecological Green Academy how to test for, and recognize, genetically modified food ingredients. Additionally, we taught our peers about some of the beneficial real-world applications of GMOs. Our educational program included a pre-learning survey, direct instruction by our biotechnology teacher, George Cachianes, and a series of three lab exercises in which the iGEM/biotech students taught the Green Academy students how to recognize genetically modified foods using common biotech lab techniques. Afterwards, a post learning survey assessed the knowledge of the Green Academy students to see if their attitude and knowledge about GMOs had shifted.
In search of two genes In order to find out if GMOs were present in common, every-day foods, such as tortilla chips and papaya, we tested these common foods for the presence of two genes: CaMV35S, which codes for a promoter, and NOS, which codes for a terminator. We specifically looked for the presence of promoter and terminator genes instead of the actual functional genes themselves because the functional gene may vary from organism to organism, depending on what qualities of the organism are being altered. In order to determine which of our samples were GMOs and which were not, we used some very common lab techniques including Polymerase Chain Reaction (PCR), which amplifies a certain piece of DNA.
We chose to use a variety of food, including fresh soy beans, tortilla chips, Fritos corn chips, papaya and a organic corn snack that claims it is made from an ancient variety of corn. We tested some foods that were labeled “non-GMO” and some that weren’t labeled at all.
Testing
We crushed up samples of each food up with a mortar and pestle, while adding small amounts of water to make a slurry. We then placed each sample into a microcentrifuge tube containing InstaGene, a chelating agent that helps to remove metal ions. We have to use this because it ensures that the PCR will be free of metal ions. After adding our samples to InstaGene, we shook the tubes and placed them into a 95°C water bath for 5 minutes. Afterwards, we centrifuged them for 5 minutes at the maximum speed, and then refrigerated them.
The next day, we removed the samples from the refrigerator and placed them on ice. We added all of the essential ingredients for PCR into a PCR tube, in addition to DNA from the samples we had centrifuged the previous day. After mixing the contents of the tube, we placed them into the thermal cycler. Finally, we used gel electrophoresis to see if fragments of DNA that would indicate that the sample is a GMO were present in the samples or not.
Lab Results:
We were surprised to find no proof of genetic modification in fresh soy beans or soy crisp snack chips, even though some sources claim that 91% of the U.S. soybean crop is genetically modified. However, in our testing the soy foods, the CaMV35S and NOS terminator bands did not appear. Interestingly enough, the cornbread mix did not show evidence of genetic modification while the same-brand cornmeal did. Please see the full data represented in the chart below:
