Human DNA Extraction Lab

Human DNA Extraction Lab Conclusion

              In this lab we asked the question, how can DNA be separated from cheek cells in order to study it. We found that there are three main steps-homogenization, lysis, and precipitation. My group and I added salt, detergent, pineapple juice, and rubbing alcohol into Gatorade and our spit. Our teacher gave us the steps of the procedure, but they were all scrambled, so based on our knowledge given in the worksheet of the lab, we put together a procedure. We weren't sure if our procedure was actually correct as our teacher wouldn't tell anyone the correct order and said we would find out by seeing of we got our DNA to appear. My whole group and I had our DNA appear in the tubes even though I wasn't sure our procedure was in the right order. This data supports our claim because homogenizing cell tissue is done with polar liquid. Salt is added because it shields the negative phosphate ends of the DNA which allows them to move closer together. Soap, or in this case, detergent, was added to lyse the cells membranes and effectively disrupted polar interactions that held the cell membrane together which released everything inside the cells to the solution. Catabolic proteases are found in many things such as pineapple juice, which we added next. A layer of alcohol is put onto of the solution containing our cheek cells. The DNA then floated to the top and we were able to collect it. 

             Our data contradicts the expected results because we forgot to add the pineapple juice until after we had added the layer of cold alcohol. I wasn't sure if our procedure was right because despite the lack of catabolic proteases, we still managed to get DNA. We also weren't very careful in pouring the alcohol into the solution so some of it probably went into the solution instead of just creating another layer. The DNA might have been more prone to come out because the alcohol went into the solution instead of the catabolic proteases, but perhaps our group was just lucky. Due to these errors, in future experiments I would recommend that groups pay very close attention to the procedure and try to remember everything when working in a lab. 

             This lab was done to demonstrate our self sufficiency and whether or not we had to be guided to put together a procedure on which we received information on. From this lab I learned that DNA is very small and anyone can take it because you leave traces of your cells everywhere which helps me understand the concept of genetics and how it can be used. Based on my experience from this lab, I would read instructions much more carefully and try to gather as much information as possible from what is given to us before we receive another lab.