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Hardy-Weinberg Lab

Hardy-Weinberg Lab. Taste Testing. PTC. Phenylthiocarbamide Compound contains sulfur Harmless chemical Found in Brassica family of plants Cabbages, brussel sprouts, kale Gives a slight bitterness. Tasting PTC. Dominant: Tasters Find low concentrations of PTC extremely bitter

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Hardy-Weinberg Lab

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  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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