Using PCR and Gel Electrophoresis to Determine Genotype

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Using PCR and Gel Electrophoresis to Determine Genotype In certain situations, it is necessary to identify DNA retreived from a sample. When there is a small sample in need of identification, Polymerase Chain Reactions are used to multiply the DNA in the sample in to many identical samples. The DNA retrieved from the reaction can then be imported into an aparatus using gel electrophoresis to compare the sample of DNA to other samples. In our experiment we learned the how to replicate tiny samples of DNA into usable amounts and how to analyze the specimine using gel electrophoresis. The samples of DNA were obtained by plucking individual hairs from students' heads and using the PCR device to replicate the DNA from the roots of the hair. The replicated DNA samples were then placed into the electrophoresis gel and the device was turned on. Using the methods discussed above we found that three of the fourteen samples, 21%, were homozygous and the remaining eleven samples, 79%, were heterozygous. We concluded that it is possible to examine small amounts of DNA by first replicating the sample using Polymerase Chain Reactions then using gel electrophoresis to determine the genotype of the DNA. The main goal for our experiment was to learn how to examine DNA when there is only a small sample present. We examined the samples of DNA obtained from student hair using the replication method of Polymerase Chain Reaction and the inspection method of gel electrophoresis. The way the PCR method works is by first mixing a solution containing the DNA, DNA polymerase primers, and certain nucleotides. Next, the solution is heated to allow the strands to seperate, then cooled to allow the primers in the solution to b... ... middle of paper ... ...q DNA polymerase to each tube while disallowing the tubes to cool and without taking time to mix the reaction solution after adding the Taq polymerase. When the PCR technique is completed, the tubes are stored at 4°C until analysis of the tubes. To alylize the PCR results with the gel electrophorese, 2.5ul of the 10x loading dye is added to each PCR reaction tube. The gel for the electrophorese consists of 1.5% agarose gel with 0.5x TBE and 200ng/ml ethidium bromide. The gels were run at 90-100 volts for 1-1.5 hours. Upon completion of the experiment we were able to examine the DNA. First, the electrophorese revealed that three of the fourteen samples were were homozygous while the other eleven were heterozygous. This conforms the fact that close to eighty percent of our population is heterozygous and twenty percent homozygous (Isprilus, 2000).

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