Ptc Testing Lab Report

PTC Testing Lab

11/12/13

Abstract:
The main purpose of this lab is to determine that you have the dominant PTC gene or recessive PTC gene. PTC testing is a method used to test for a genetic trait. People who have dominant gene taste PTC (phenylthiocarbamide), and people who have recessive do not taste PTC. This trait is passed genetically from parents to their children, so that if a person has the trait, then at least one of their parents had the trait as well (New York Science Teacher). Approximately 75% of individuals are tasters, and 25% are non-tasters (StewartKhataan). Gel electrophoresis is used to separate DNA fragments by length of molecules. Smaller segments move more easily than larger segments.
We began this lab by isolating DNA. We obtained 14 ml of sterile saline solution and poured this solution into my mouth for extracting DNA from my cheek cells. We transferred the solution into a centrifuge tube and centrifuge my tube at top speed for 10 minutes to obtain a cheek cell pellet. After pelleting, we poured out liquid from the tube as much as possible. However we had to make sure that we did not interrupt pellet while pouring out liquid. We placed this tube on ice and added 500 μl of 10% Chelex to the pellet. We used a micropipette for doing this. We transferred 500 μl of the sample to a 1.5 ml microcentrifuge tube and it boiled for 10 minutes and placed the tube on ice for 1 minute to isolate the DNA. After the DNA was extracted and isolated, we used PCR to amplify the fragment of the Tas2R38 located on chromosome 7. We added 5 µl of my DNA to the PCR tube by using micropipettes. We used restriction enzymes to cut my PCR product. We added 20 µl of my PCR product to the restriction enzyme digestion tube containing 1 µl Fnu4HI restriction enzyme and 2.5 µl 10X NEBuffer and placed in a 370C waterbath for 1 hour. The amplified region was digested and we used electrophoresis gel to determine that we had the bitter taster gene which is Tas2R38. We assembled the electrophoresis casting tray and weighed out 0.5 g of agarose into a flask. I
However, according to our data, 83% of individuals were taster and 17% were non-tasters. I think reason of this error is we did phenotype experiment with just small amount of individuals. According to standard data for phenotype of individuals related to ethnicity, 10~24% of Asians were non-tasters (StewartKhataan). In our data, 13.51% of Asians were non-tasters and this result was very close to standard data. For Blacks, standard data expected there are 2.14~4.89% non-tasters (StewartKhataan). In our data, 7.14% of Blacks were non-tasters. Our result was slightly off than standard data, and I think this error came from small population for sample. For Whites, standard data expected there are 31% non-tasters (StewartKhataan). In our data, 31.82% of Whites were non-tasters. This result was quite close to the standard data. For Indians, standard data expected there are 41% non-tasters (StewartKhataan). However, in our data 0% of Indians were non-taster. I think reason of this huge error came from extreme small amount of population for sample. We only had 1 Indians for this experiment. According to standard data for phenotype of individuals related to gender, the percentage of tasters of men and women are about the same (StewartKhataan). In our data, 84.2% of females were tasters and 79.2% of males were tasters. This result matched with standard