After learning all about genetically modified organisms over the past week from Mr.Chugh, we have finally finished our three day lab and have found results. Each lab table was able to bring in a fruit or vegetable to test to see if it was genetically modified. On the first day we extracted the DNA from our food samples (our control and test foods). We measured out about one gram of each substance and then added water into a mortar where we used a pestle to form a "slurry". Once we had ground the substance smooth enough we pipetted it into a test tube. We then added our test tubes to a water bath at 99 degrees Celsius for five minutes, followed by centrifuging for five minutes. That completed our first day of extracting genetic material from our test food.
On the second day, we returned and added "master mix" to each sample. After adding it to each PCR tube we put it in the thermal cycler. The cycler goes through three cycles. The first is at about 95 degrees Celsius, this is where denaturization occurs (DNA is unravelled), the second temperature change is to about 60 degrees Celsius where the primer binds, and the last stage is about 72 degrees where DNA polymerase appears.
On the third day of this lab, where we did gel electrophoresis. After retrieving our PCR tubes, we added loading dye to each sample and mixed them. Next, we added 20 micro liters of each sample into the gel. After loading them in we ran an agarose gel for 3 minutes on 200 V.
When we returned on the fourth day, we found our results! Our food (broccoli) was organic, meaning it was not genetically modified! After evaluating our electrophoresis we found bands in the second, fourth and sixth lanes. These were the lanes that had GMO primers added to them, meaning they would show up in our testing, unlike the plant primers because the plant primers were looking for non-modified genes to code for. The GMO primers were looking for modified genes because it can only copy them if it recognizes the genes.
Possible causes for error: Our results could have been more accurate had the experiment been done in a sterilized lab with better pipetting and more precise timing with water baths.
http://www.youtube.com/watch?v=dvlpCxjxC1g (picture is a little blurry)
A+ Outstanding!
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