KS5: Question of Taste: Using PCR to Investigate Taste Genetics

Question of Taste is a hands-on molecular biology practical that allows KS5 students to investigate their ability to taste phenylthiocarbamide (PTC) at both the phenotypic and genetic levels.

During this five-hour lab session, students use research-grade equipment and techniques to investigate their own DNA. They carry out polymerase chain reaction (PCR), restriction enzyme digestion and gel electrophoresis to identify genetic differences associated with PTC tasting.

Students begin with a taste test to determine their PTC tasting phenotype. They then:

  1. Extract DNA from their own cheek cells.
  2. Use PCR to amplify a specific region of the TAS2R38 taste receptor gene, which is associated with the ability to taste PTC.
  3. Carry out a restriction enzyme digest of their PCR products to distinguish between different TAS2R38 alleles.
  4. Use gel electrophoresis to separate and visualise the resulting DNA fragments.
  5. Compare their genotype and phenotype to investigate the relationship between genetic variation and taste.

Students also compare their results with those from chimpanzees, using genetic data to explore phylogeny, genetic variation and convergent evolution.

Science learning outcomes

By the end of the session, students will be able to:

  1. Explain how DNA codes for proteins and how genetic variation can contribute to heritable traits, including variation in our sense of taste.
  2. Understand how DNA can be extracted, amplified and analysed using molecular biology techniques.
  3. Gain practical experience in micropipetting, setting up PCR reactions, restriction enzyme digestion and gel electrophoresis.
  4. Interpret experimental results to identify genetic differences between individuals.
  5. Apply molecular genetic data to broader biological concepts, including phylogeny and convergent evolution.
  6. Relate genotype to phenotype using their own experimental results.

Practical information

The session takes place in a small research lab and is designed to provide students with experience of techniques used in modern molecular biology research. The maximum group size is 20 students with up to two accompanying members of staff.

The practical is fully funded and available for students educated in the state sector