In this laboratory experiment we tested for genetically modified organisms (GMO) in our favorite snacks. The use of GMOs in our food today is the talk of much controversy. There is much speculation as to whether GMOs are actually healthy for people to consume. In all actuality, GMOs have been around since before people knew that they existed. Farmers have been genetically modifying (GM) crops to breed them for certain traits for centuries. A genetically modified crop has been enhanced through the cross breeding and insertion of genes to make them more resistant to outside forces, such as pesticides and infestation of insects, and in doing so will ultimately make the farm produce a high yield of production. The United States is one of the few countries that does not have to label whether or not their food contains GMOs.
A GMO is ‘an organism in which the genetic material has been altered in a way that does not occur naturally by mating and/or recombination’ (Bio-Rad power point, 2013). People who are anti-GMO feel strongly that there will be an evolution of super-weeds and super-bugs and the crops will have to undergo further modification to make them resistant to the pests all over again. People who are pro-GMO believe that it is better because there are less toxic chemicals used that could potentially destroy the environment and endanger the lives of those who come in contact with them (Lab Manual: Background).
There are a few different ways to test for the presence of GMOs. We used the polymerase chain reaction (PCR) method. This method enabled us to make copies of or amplify sections of DNA sequence exponentially. This makes it easier for us to see the different bands when the gel electrophoresis is performed at the end of the experiment. Another way to test for the presence of GMO would an antibody test called enzyme-linked immunosorbent assay (ELISA), which detects for proteins that are specifically found in GM crops. ELISA is not particularly useful for testing highly processed foods, because the proteins were probably obliterated.
PCR is often used to test for GMOs because it takes a look at the GMO sequence in GM foods. DNA is more resistant than proteins in processing so it can be extracted from even the most heavily processed foods. DNA from whole plant differs from DNA extracted from processed foods. The difference is that when a whole food undergoes DNA extraction it tends to keep its proteins whereas processed food tends to lose its proteins.
In this experiment we perform analysis on both a GMO and known non-GMO food controls. We do this because we need to compare them in order to give valid results. The reason why we have both a positive and negative control is because if the test came out positive and it was supposed to be negative, then we wouldn’t know if the test was faulty somewhere or if was really supposed to produce a positive result.
At the end of the experiment we resolve the PCR products by Gel Electrophoresis. We do this because the Gel Electrophoresis separates the PCR by size. The DNA products separate according to size in through the electrophoresis gel because it has a negative charge whereas the gel itself has a positive charge. The smaller fragments move faster than the larger ones. We place a molecular weight ruler of a known size alongside the experimental and control samples. This helps compare the migration distance of the experimental fragments with the migration distance of the fragments of the known size that make up the molecular weight ruler.
At the beginning of this experiment I believed that the DNA extracted from my grocery store food control (Corn Meal) would contain GMOs and the non-GMO control (Oat Meal) would not contain GMOs. This experiment used PCR to detect for CaMV promoter: which is commonly used in genetically modified crops. It is the promoter gene found in the Cauliflower Mosaic virus. This lab is used to help educate us more about what we consume and the decisions we should be making over the GMO controversy.