Background: PTC testing is a method used to predict a genetic trait for bitter tasting ability.
People who are dominant taste PTC (phenylthiocarbamide) [P], and people who are recessive
do not taste PTC [p]. This trait is passed genetically from parents to their children, so that if a
person has the trait, then at least one of their parents has the trait as well. (Use the letter P to
represent the alleles)
Write the genotype for people who do not taste PTC:
• Are they homozygous or heterozygous?
Write the possible genotypes for people who do taste PTC:_
Are they homozygous or heterozygous?
Purpose: In this activity, you will taste two pieces of paper to see if you are dominant
or recessive for the genetic trait. You will use this information to predict the possible genotypes
and phenotypes for your parents.
Biology Content Standard:
2e. Students know why approximately half of an individual's DNA sequence comes from
each parent.
Hypothesis:
Do you think you will be a Taster or a Non-Taster?
Pre-lab Questions:
1. What is a genotype?
2. What is a phenotype?
3. What is a dominant trait?
4. What is a recessive trait?
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