Explore how small genetic changes can change our ability to perceive the world around us.
The human sense of taste is composed of an intricate neurophysiological network, but as we’ll see in this lab, it only takes a few small changes in our DNA to change the way we taste. Alleles of the TAS2R38 taste receptor gene can confer the phenotypic ability to taste the chemical Phenylthiocarbamide (PTC) and other bitter flavors. Students will PCR amplify your own TAS2R38 taste receptor gene and use DNA restriction analysis to determine whether they have taster or non-taster version of the gene.
Key info and benefits:
- Techniques: Micropipetting, DNA extraction, PCR, restriction digest, gel electrophoresis
- Time required: 120 minutes
- Suggested skill level: High school
- Reagents for 8 lab groups of 4 students each (32 students). These reagents are compatible with blueGel™ or other standard DNA electrophoresis systems.
- Students determine whether they are homozygous or heterozygous for this trait, and correlate their genotype with their own ability to taste PTC (and foods that contain related chemicals, such as broccoli).
- X-TractTM DNA extraction buffer
- 2X EZ PCR Master Mix, Load-ReadyTM
- PTC Lab Primer Mix, 2X concentrate
- Restriction enzyme
- 100 bp DNA ladder
- See notes for extra requirements
- See resources below to download the lab teacher's guide and student guide. Contact team @ Southern Biological for answers key.
- To perform this lab, you will require electrophoresis equipment; such as electrophoresis chamber, agarose, TBE buffer and Midori green gel stain (or methylene blue stain if you are using traditional electrophoresis equipment). Our electrophoresis starter kit contains the hardware and reagents required. Additionally, you will require a thermal cycler. We recommend the mini8 thermal cycler or the mini16 thermal cycler plus PCR vials, a 0.5-10μL micropipette and tips and a 100-1000μL micropipette and tips.
- You will also require PTC papers and ideally control papers.
- For best results, we recommend running your gels in the blueGel electrophoresis chamber. If you do not have a blueGel electrophoresis unit with built-in illuminator, we have a transilluminator onto which you can place your gels to visualise your results immediately after the electrophoresis run is complete.
- These DNA samples require frozen storage, which will keep them stable for 12 months.