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PTC - Can you taste bitter?

PTC - Can you taste bitter?. Internet Link – ScienceNow Picky Eaters Video. V: Drive Link – ScienceNow Picky Eaters Video. PCR Lab – PTC Taster. What DNA sequence are we going to copy? TAS2R gene Encodes a PTC taste receptor (senses a bitter taste). The Anatomy of Taste.

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PTC - Can you taste bitter?

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  1. PTC - Can you taste bitter? Internet Link – ScienceNow Picky Eaters Video V: Drive Link – ScienceNow Picky Eaters Video

  2. PCR Lab – PTC Taster • What DNA sequence are we going to copy? • TAS2R gene • Encodes a PTC taste receptor (senses a bitter taste)

  3. The Anatomy of Taste Genetics Science Learning Center

  4. PCR Lab – PTC Taster • What do we do with bitter taste receptors? • Many toxic plants are bitter tasting • People with high levels of bitter taste receptors are less likely to smoke.

  5. PCR Lab – PTC Taster • Chance discovery

  6. Background on TAS2R38 Gene (Bitter Taste): 1930’s -- first reported on variation of ability to taste PTC (phenylthiocarbimide) PTC bitter taste has been widely used in Mendelian genetics studies Bitter taste Controlled by group of bitter taste receptors Gene family = TAS2R Bitter taste receptors are TRANSMEMBRANE 7 helical regions that wind through the cell membrane

  7. DNA… TAS2R38: Chromosome 7 1002 bp long

  8. …to Protein Non-tasters differ from tasters at 3 locations in the TAS2R38 gene…

  9. Protein picture… Cytoplasmic

  10. PCR Lab – PTC Taster • Being a “taster” is a dominant trait • Homozygous dominant – TT • Heterozygous – Tt • Homozygous recessive - tt TASTERS NON-TASTERS

  11. PCR Lab – PTC Taster 221 bp • Non-taster PCR product - Taster PCR product - 221 bp SNP – Single Nucleotide Polymorphism. One “letter” makes a big difference.

  12. Determing PTC genotype Extract DNA from cheek cells Amplify TAS2R38 region (PTC) using PCR Digest PTC-PCR product with HaeIII PCR product is 221 bp Taste allele (T) = one HaeIII site Sizes of 177 bp and 44 bp Non-taste allele (t) = no HaeIII site Remains uncut - 221 bp Can you predict bands for these genotypes? TT (PTC strong taster) Tt (PTC weak taster) tt (PTC non-taster)

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