Name___________________ Date_________ Period_______ Olson PTC-Lab GL:9-11
What Do You Taste?
The ability to taste PTC is a genetically heritable trait that follows Mendelian patterns. To understand this lab you will
use your knowledge of genes, alleles, genotypes, phenotypes, dominance and punnett squares: probability and
ratios. PTC paper is used to detect the tastebuds that taste bitter. These tastebuds are located at the back of the
tongue and in the throat. Unlike sweet, sour and salty taste buds, there are many different types of bitter taste buds.
Because of this not everyone has all the same bitter tastebuds.
Have you ever tasted something like medicine that leaves an after taste? It’s a bitter taste and you only taste it in the
back of the tongue. The same can be done for sour also. You can taste it on the back and sides of your tongue.
 There is only one type of sour taste bud (detects H+), only one type of salt taste bud
(detects Na+), and only one type of sweet taste bud (detects sugar), but there are
many types of bitter taste buds.
Do you think the ability to taste is likely to differ among people? Yes or No
Why do you think different people will be able to taste different bitter tastes? _______________________________
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Write a hypothesis about the difference in taste ability. Remember to use “If Then, Because” format.
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Materials
PTC taste strips
Control taste strips
Mini Zip-lock bags
Procedure
You will follow these steps to find out which compounds you taste.
1. Take one control taste strip from the bag marked “control”.
2. Place the taste strip on your tongue. Be sure to test all the regions of your tongue. “You should not taste
anything.” It should taste like paper. “Remember what it tastes like!”
3. Remove the taste strips from your mouth immediately throw it in the trash can. Do not place it on your lab
table, stool or desk!
Idea came from Spice by Deena Westbrook & Marbie Caruso. Annotations by: Charlene Olson 6/2010 1 4. Take one PTC taste test strip from the marked bag “PTC”.
5. Place the taste strip on your tongue. Be sure to test all the regions of your tongue.
6. Remove the test strip from your mouth, and immediately throw it in the trash can. Do not place it on your
lab table, stool or desk!
7. Record whether or not you taste PTC in your chart. If you tasted nothing, or if it tasted the same as the
control test, you are a non-taster. Otherwise, you are a taster.
8. Now you will be given 4 test strips to take home and ask that your parents take the test also. With the two
left you may test either 2 family members or your grandparents. Record your finding on the chart and bring
the lab handout back to school.
Lab Group Members
PTC Taster
PTC Non-taster
9. Was there a lot of variety in your classmates’ ability to taste? Is this evidence for against your hypothesis?
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10. Do you think your family members could taste the same as you, or do you think their taste abilities will differ
from yours? Why?______________________________________________________________________
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Family Members Tested
PTC Taster
PTC Non-taster
11. What were your findings when testing family members with the PTC? ______________________________
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12. Is there a relationship between the ability to taste one bitter substance and the ability to taste another?
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On the back of this handout you will now complete a punnett square of your families’ abilities to taste and
see what the probability and ratios could be for a family member to taste the PTC.
Idea came from Spice by Deena Westbrook & Marbie Caruso. Annotations by: Charlene Olson 6/2010 2