DNA Extraction Lab

     In this lab we asked the question, how can DNA be separated from cheek cells in order to study it. We found that it is quite a long procedure. Part of this lab was to put the steps of the procedure in the correct order. We found that the first step was to gently scrape the sides of your mouth with your teeth and rinse gatorade in your mouth for thirty seconds. We used gatorade because it is polar. Because gatorade is a polar liquid, it homogenized the cell tissue in our mouth. Then we added salt to the solution which smooths the way for precipitation. It does this by letting the negative phosphate ends move closer together. Then we added pineapple juice to the mixture, a catabolic protease, which broke down histones. The next step was to add soap to the mixture to disintegrate (lyse) the cell membranes. This distorts the polarity that holds the cell membrane together and in turn, releases all contents into the solution. The final step was to slowly add alcohol, a nonpolar substance, to the test tube that contained the gatorade solution. Because DNA is polar, it comes out of the gatorade solution into the alcohol that was layered on top of the gatorade as a precipitate. We then extracted the DNA from the alcohol layer with a transfer pipette and put it into tiny plastic vials.

      Our data contradicts the expected results because we added the salt to the solution after we had put the alcohol into the test tube. This step is in the wrong place, the salt should have been to the solution much earlier in the experiment. This misstep may have meant that the cell membranes were never disintergrated (lysis). The second possible error is that we also added the pineapple juice after the alcohol was in the test tube. This could have damaged our results because the catabolic proteases in the pineapple juice could not further break down the histones in the solution because they were added to the solution too late. Due to these errors, in future experiments I would recommend starting the experiment earlier in the period so that we would have more time to redo the experiment in the correct order of steps.

     This lab was done to demonstrate all the steps that are needed and what they do, to separate DNA from our cheek cells in order to study it. From lab I learned that it is possible to extract DNA from our cheek cells with common household items, this helps me understand the concepts of catabolic proteases, polar and nonpolar substances. I thought that it would be a much more complicated process, however it is quite simple. Based on my experience from this lab, I could extract DNA from my cheek cells which could be used for tests to test for the probability of genetic disorders.