In our genes, multiple different alleles determine whether one person will have a certain trait or not. Alleles are what make-up our genotypes and in this lab, we wanted to determine the genotypes of our class in the two loci: TAS2R38 and PV92. The TAS2R38 locus codes for a protein that involves the bitter taste of PTC; the gene determines whether or not a person will taste the PTC paper as very bitter or no taste at all. People with the “T” allele are tasters while those that are homozygous recessive (tt) are non-tasters. The taster locus can be found chromosome 7.3 The two different alleles present in the could be due to the effect of evolution and natural selection because the same can be found in chimps.4 The PV92 locus does not code for any protein but rather involves an Alu element that is 300-bp long. A person with the “+” allele would have the Alu element making that sequence longer while those with the “-“ allele don’t have the element and would have a shorter sequence. This locus can be found on chromosome 16.3 There are multiple Alu sequences found among primate genomes but there are human specific sequences such as the one found on the PV92 locus.1 In the experiment, student DNA was collected from cheek cells and PCR was used to target the loci and amplify the region of DNA. In the taster gene, after amplification, a restriction digest was performed to differentiate between the two alleles. The digest was able to show differentiation because those with the “T” allele would have two bands from gel electrophoresis and those with “t” will have one band because the restriction enzyme doesn’t cut it. For the PV92, we were able to distinguish between the alleles due to the added length of the Alu element. Those with “+” have longer sequences so the band would indicate a long base-pair while those with “-“ would have shorter sequence and heterozygotes would have 2 bands that resemble both.3 Then once we figured out the genotypes, we used the data to figure out the allele frequencies through Hardy-Weinberg equations. After that we used the frequencies to calculate whether our data fit Hardy-Weinberg equilibrium or not. To determine its fitness, we used the chi-square test to determine a P-value and decide whether or not to reject the null hypothesis. My hypothesis was that the class data would not fit Hardy-Weinberg equilibrium because it violates conditions like the infinite population and our class is not infinite. The null hypothesis of the experiment was that the data does fit the Hardy-Weinberg Principle.
Materials and Methods
First, we figured out the phenotypes of tasters versus non-tasters by tasting a strip of the PTC paper. Those who tasted nothing were classified as NT, bitter taste was T, and partial taster was PT. Then we started the DNA extraction: DNA was obtained from each student’s cheek cells to use as the template for PCR amplification using a collection swab and put the DNA into a DNA Extraction Solution....