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To Taste Or Not To Taste?
PTC: Genes and Bitter Taste
Ms. Z
1/8/10
Phenylthiocarbamide
 Accidentally discovered in 1931 by Arthur Fox.
 Tastes extremely bitter to some people but not others.
 Chemical structure resembles toxins found in plants.
The PTC Gene
 The ability to taste PTC is determined by a single gene,
which codes for a taste receptor on your tongue.
 There are 2 alleles: taster (T) or non-taster (t).
 For the PTC gene:
 How many genotypes are possible?
 How many phenotypes are possible?
To Taste Or Not To Taste?
 You will inventory the PTC-tasting trait in your family and
build a pedigree.
 Are you testing for genotype or phenotype?
Evolutionary Importance of
Bitter Taste
 Many natural bitter substances are toxins.
 Plants produce many toxins in order to protect themselves
from being eaten.
 Bitter taste evolved in early humans to prevent consumption
of poisonous plants.
Health Applications
 People who find PTC bitter may be less likely to smoke,
because they find the taste of cigarettes bitter.
 The ability to taste PTC may also correlate to food
preferences.