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Understanding Taste Genetics: PTC Lab Experiment

Discover the role of alleles with PTC taste testing in a fun science lab. Explore how gene variations affect your ability to taste bitterness and saltiness. Learn about the dominant and recessive alleles related to PTC tasting, and how they determine your preferences for certain foods. Through experiments with compounds like thiourea and sodium benzoate, gain insights into your taste sensitivities and genotype frequencies. Unleash the science behind your flavor perception!

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Understanding Taste Genetics: PTC Lab Experiment

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Presentation Transcript

  1. Hardy-Weinberg Lab Taste Testing

  2. PTC • Phenylthiocarbamide • Compound contains sulfur • Harmless chemical • Found in Brassica family of plants • Cabbages, brussel sprouts, kale • Gives a slight bitterness

  3. Tasting PTC • Dominant: Tasters • Find low concentrations of PTC extremely bitter • Homozygous tasters seem to have a very low tolerance • Find it more bitter than heterozygous tasters • Oddity: you can only taste it if it is dissolved in your own saliva • Recessive: Non-tasters • Report little or no taste

  4. How does this reflect on role of alleles? • Alleles are different versions of same gene. • Gene encodes a protein receptor for PTC • Found on chromosome 7 • Tasters have a gene that encode • Proline, Alanine and Valine at positions 49, 262 and 296 • Non-tasters have a gene • A, V and I at these three positions

  5. Sodium benzoate • Poly-unsaturated fat • Used in food to inhibit microbial growth • Works best in an acidic environment

  6. PTC bitter/Sodium benzoate salty Tend to like sauerkraut, buttermilk, turnips and spinach more than average PTC bitter/Sodium benzoate bitter Tend to dislike sauerkraut, buttermilk, turnips, spinach less than average Relation to a person’s fave foods

  7. Most common taste groups • Ranked in order of most common combos PTCSodium Benzoate • 1. Bitter salty • 2. Bitter sweet • 3. Bitter Bitter • 4. Tasteless Salty • 5. Any other combinations

  8. Lab Methods • Part I: PTC Taste/NonTaste • Step 1: Place control paper on tongue/chew a little • Negative control: you shouldn’t taste anything • Something to compare the other papers to… • Step 2: Place PTC(blue paper) on tongue • Record what you taste • If you don’t taste anything, chew it a little and record again • Are you a taster or a non-taster?

  9. Lab Methods…pt 1 • Step 3: Record your PTC data on the board and collect all class data • Step 4: Calculate the allele frequencies and the genotype frequencies of the class

  10. Lab Methods pt 2 • thiourea • How many of you can taste one but not the other?

  11. Lab Methods: Pt 3 • Sodium benzoate

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