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Friday, December 2, 2016

DNA Extraction Lab

In this lab, we asked the question, "How can DNA be separated from cheek cells in order to study it?" We collected information about the three main steps of DNA extraction. Homogenization, lysis, and precipitation. We found that DNA from cheek cells could be extracted and studied if the correct steps are used in the correct order. The correct steps the proper order are as follows:
  1.  Measure 2.5mL of Gatorade into a paper cup
  2.  Scrape both sides of the inside of your checks using your teeth.
  3.  Vigorously swish in your mouth for 30 seconds.
  4.  Spit solution back into cup
  5.  Add a tiny punch of salt
  6.  Carefully poor solution into a test tube about 1/3 to 1/2 of the way up
  7.  Add 10 drops of detergent/soap.
  8.  Add 5-10 drops of your enzyme (pineapple juice)
  9.  Let sit for 5 minutes and record observations.
  10.  Tilt the tube at an angle and slowly add cold alcohol along the side of the test tube. You do not want the two layers to mix. The amount added should be about the same as the Gatorade mixture.
  11.  Collect the DNA and alcohol and carefully, with a transfer pipette, and place in a microcentrifuge tube. Do your best to only transfer DNA and Alcohol to your tube.
  12. Cover the tube with your thumb. Carefully invert 6 times. Be careful not to shake too much. You do not want soapy bubbles to form.
  13. Wait for another 5 minutes and record observations. 
Evidence from Experiment: During our first trial we switched steps 11 and 12, and thus we were not able to extract DNA, but when we did these steps in the correct order, we were able to extract DNA.

Reasoning: This evidence supports our claim, because during the first trial, which failed, the two layers, of alcohol and Gatorade, mixed and thus we were not able to separate DNA. However during the second trial which succeed we only inverted the tube after separating DNA, and thus was able to get the DNA.

Possible Error 1: The first error that we made was switching the order of the steps. Part of our lab was to put random steps in the correct order. We ended up switching steps 11 and 12, thus inverting the tube 6 times (and mixing the alcohol and Gatorade solutions), before separating the DNA. The effect of this error on the overall results was the fact that we were not able to get the DNA separate and the end of the experiment.

Possible Error 2: That was the only error we made in the experiment, but a hypothetical error could have been not adding the alcohol while the test tube was tilted. The effect of this would have been the same as the effect in PE 1, as the DNA would not separate at the end of the experiment.

This lab was done to help us understand the process of DNA Extraction, including the 3 main steps - homogenization, lysis and precipitation. I can relate this lab to the vodcast about "Your Genetic Code." The concepts from that vodcast, really helped me to do this lab, and my overall understanding of DNA was solidified through this lab process. The fact that we first messed up and then fixed our mistakes, really helped me understand some of the important concepts, like the enzymes breaking down the DNA.

From this lab, I learned the correct process of DNA extraction, and now I could extract DNA from any cell. This would be helpful if I wanted to study DNA, especially discrepancies in genetic variation, in the future as a scientist. Another outcome I learned from this lab is to slow down. At first, I though for sure that the first procedure we came up with was correct, but in hindsight, I feel like if I thought about it a bit more, I would have been able to see the mistake and correct it before we started the experiment. This teaches me to double check everything I do, and most importantly, slow down.



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