Genetics of Taste (Caroline Ramirez)
Title: Genetics of Taste
Principle(s) Investigated: Genes, DNA, Chromosomes, Probability, Dominant traits, Recessive traits, Alleles, Phenotypes, Genotypes, Heredity, Genetic Variation.
Standards:
Standard # or ID
CCSS. RST.9-10.3
Common Core Standards
Standard Description
Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
Materials:
- PTC taste paper
- Control taste paper
- Sodium benzoate taste paper
- Thiourea taste paper
- Small paper cups (one for each student)
- Drinking water or flavored beverage
Procedure:
- Watch the Amoeba Sisters: Alleles and Genes introductory video and complete pre-lab questions.
- To get an idea of what you are about to taste, check out this video called “Are You a Supertaster?”
- Place a strip of control paper on your tongue and leave it there for a few moments. Do not chew or swallow the paper. Note any taste or sensation you perceive onto the data table below (0=no taste, 1=some taste, 2=super taster). Now discard the used paper onto your paper towel.
- Drink a small amount of water before continuing.
- Repeat steps 2 and 3 for PTC, Thiourea, and for the Sodium Benzoate paper.
- Compare your results with others in your group. Note any similarities and/or differences among your group’s taste preferences.
Student prior knowledge:
Students should have a basic understanding that chromosomes are made up of DNA and contain genes that code for traits. They should know that some of these traits are dominant and others are recessive. They should also know that traits are inherited from the alleles that are acquired from each parent.
Explanation:
This demonstration shows that not all traits are visible. Students will be able to observe/identify correlations in the inheritance of taste genes. Studies suggest that there might be a correlation between supertasters with gender and ethnicity. Women have a higher prevalence of being supertasters when compared to men. Latinos and African Americans are also more prevalent to be supertasters when compared to Caucasian and Asian.
Questions & Answers:
1. Assume that the ability to taste PTC/Thiourea/Sodium Benzoate is controlled by a single, dominant gene. Based on the frequencies of tasters and nontasters in your class, determine the frequencies of the PTC/Thiourea/Sodium Benzoate taster and non-taster alleles. Using this information, calculate how many people in your class should be heterozygotes, homozygous dominant, and homozygous recessive.
Answer: Calculations will vary depending on class results. Students should realize that a score of 0 = recessive, 1 = heterozygous, 2= homozygous dominant to be able to calculate the percentage.
2. Does there seem to be a correlation between ethnicity/gender and the ability to taste PTC. Which ethnicities/gender seem to be able taste PTC?
Answer: Calculations will vary depending on class results. Women have a higher prevalence of being supertasters when compared to men. Latinos and African Americans are also more prevalent to be supertasters when compared to Caucasian and Asian.
3. Does there seem to be a correlation between ethnicity/gender and the ability to taste sodium benzoate. Which ethnicities/gender seem to be able taste sodium benzoate?
Answer: Calculations will vary depending on class results. Women have a higher prevalence of being supertasters when compared to men. Latinos and African Americans are also more prevalent to be supertasters when compared to Caucasian and Asian.
4. Does there seem to be a correlation between ethnicity/gender and the ability to taste thiourea? Which ethnicities/gender seem to be able taste thiourea?
Answer: Calculations will vary depending on class results. Women have a higher prevalence of being supertasters when compared to men. Latinos and African Americans are also more prevalent to be supertasters when compared to Caucasian and Asian.
5. Does there seem to be a correlation between having all the genes or not having any of the genes?
Answer: Yes, studies have shown that there is a correlation between having all the taste genes. Individuals that are supertasters for PTC tend to be supertasters for Thiourea and Sodium Benzoate.
6. Why might the ability to taste PTC be an advantage or disadvantage?
Answer: Studies indicate that individuals with the "strong tasters" PTC gene variant were less likely to be smokers. This may indicate that people who find PTC bitter are more likely than non-tasters to find the taste of cigarettes bitter and may be less likely to smoke.
Other studies suggest that there may be correlations between the ability to taste PTC and preference for certain types of foods. This may be why some of us think that broccoli is just too bitter to eat.
Applications to Everyday Life:
1. Studies indicate that individuals with the "strong tasters" PTC gene variant were less likely to be smokers. This may indicate that people who find PTC bitter are more likely than non-tasters to find the taste of cigarettes bitter and may be less likely to smoke.
2. Other studies suggest that there may be correlations between the ability to taste PTC and preference for certain types of foods. This may be why some of us think that broccoli is just too bitter to eat.
3. Plants are much more likely to contain toxins than animals. Strict herbivores have fewer bitter taste genes than omnivores or carnivores. Which explains why herbivores have a higher tolerance for the toxins found in plants.
Data Table:
Videos:
Photograph:
