Testing for GM foods via DNA extraction, PCR, and gel electrophoresis

Introduction:

a) GMO stands for Genetically Modified Organism. Many GMOs are agricultural plants, which have been enhanced to be cold or drought resitant, pest resistant, bigger, stronger, healthier, etc. Genetic modification can be used to create the "perfect apple" that can withstand forces of nature and be produced in vast amounts, increasing the farmer's yield and profit.
GMOs are made by inserting a plasmid with a gene of interest (say, a gene for a redder color) into agrobacteria. Usually the plasmid is a Ti plasmid, meaning Tumor-inducing. The plant is then infected with the agrobacteria containing the Ti plasmid and the plant accepts the bacteria and allows the protein to be made from the red-color gene. The plant's fruit then becomes a beautiful red color!



GMOs can be identified by a certain method called PCR. PCR stands for Polymerase Chain Reaction and it involves making many copies of DNA so the DNA can be easier to test. DNA polymerase, a primer specific to the Ti plasmid, nucleotides, and plasmid DNA are needed for PCR to occur.
The controversy surrounding GMOs involves a conflict between technology, natural selection, and morals. Some people are greatly in favor of GMOs, saying that humans are only speeding up the process of natural selection and we have the technology so why not use it? Others say that GMOs go against nature and humans have no right to "play God". GMOs also result in a decrease in genetic variation in a population, which can have terrible consequences if a certain strain of virus were to emerge - the entire population of crops would be rapidly wiped out. An example from history - the potato famine in Ireland. Too much dependence on one type of crop is bound to result in catastrophe. But whether humans will be able to resist the possibility of creating and shaping "perfect" crops, animals, and maybe even humans is doubtful.



GloFish - the first genetically modified pet

b) The purpose of this lab is to test grocery store produce to see if it is genetically modified. This can be done in the real world as well - scientists must varify that a farmer's crop is organic by performing similar tests as the one we will do in class. A fruit is not organic if it has been genetically modified.
c) We will be using many techniques for DNA extraction in this lab. First, we will use a mortar and pestle to grind up the produce, breaking open the cell walls. Next, a hot water bath will be used to lyse open the cell and nuclear membranes. This leaves the DNA vulnerable, so Instagene matrix beads will be added to kill the DNAse in the cells. DNAse is present in all cells to kill foreign DNA - in this case, we do not want DNAse to kill the cell's own DNA, so the DNAse must be killed first. During PCR, we will use two primers - one to target the plant DNA (green primer) and the other to target GM DNA (red primer). The green primer serves as a control - all plant cells contain plant DNA, so if the plant DNA does not show up during gel electrophoresis, then we know the lab was not successful. If the plant DNA does show up, then we know PCR worked and if there is no GM DNA that shows up, then we know that the plant is not a GM product. Gel electrophoresis is used to separate and analyze the DNA found in the cells.
d) We are testing for GM DNA (the Ti plasmid) in the plant cells. That is the variable. Plant DNA is the control (as explained above). My hypothesis is that the non-organic produce (the corn, apple, etc.) will be genetically modified. Some 85% of non-organic foods are genetically modified. But the organic foods will be all natural.

Results:

According to the results, the bands of our test foods match the bands of the GM+ food - thus, all our test foods (the corn powder and the lettuce) are genetically modified.