Ptc Taster Genomic Analysis Lab Report

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PTC Taster Genomic Analysis Lab Report

Laboratory Goals: 1. Determine Taster Phenotype 2. Isolate DNA from each individual 3. Determine Taster Genotype

If I am a taster, then my genotype for PTC taster must be either TT (homozygous dominant) or Tt (heterozygous)

I – Results:

This experiment aimed to investigate the allele frequency of the PTC taster gene (TAS2R38) in a small population, represented by the students in class. The genotype obtained from genomic analysis (via PCR and gel electrophoresis) confirmed that the genotypic result is consistent with the phenotypic result observed at the beginning of the lab.
However, DNA fragments of 3 lab subjects didn’t show up on the gel. The allele
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The PTC gene itself is particularly noteworthy. Researches suggested that the gene is strongly correlated to natural selection and defense mechanism in plants. Bitter compounds similar to PTC have been found in a wide variety of plants, the bitter toxins discouraged herbivores and other threads from violating the plant. Recent researches also found that there is variation in PTC gene haplotypes, beside the two common alleles (which contradictory to the notion that the PTC gene is a perfect example for a Mendelian trait).
The sequence of this gene is show in Figure 3. The differences between the alleles are distinguished by 3 SNPs that marked red in the figure. The variation of base pairs in these SNPs resulted in synthesis of different polypeptides (proteins) and ultimate affected the ability to taste bitter substances. Tasters will have proteins that allowed the bitter toxin to bind to the taste receptors while non-tasters don’t.
This lab analysis allowed me to further my understandings and apply my knowledge of the genetic code, DNA structure and replication, as well as gave me an opportunity to practice my lab skills such as PCR, restriction endonucleases, and electrophoresis.

Figures and Tables

Figure 2. Restriction Enzyme Fnu4H1 activity.

Fnu4H1 is an enzyme that cuts DNA at specific restriction sites. Fnu4H1 digested DNA fragments from PCR to identify if the lab subjects have a C or a T at position 785 (PTC taster gene location,