PTC (phenylthiocarbamide) is a chemical that is considered “bitter” in taste. PTC has a molecular structure that is similar to chemicals found in poisonous plants. One thought is that this gene played a part in the taste receptors for these other poisonous chemicals. There seems to be a correlation between PTC tasting and the dislike of broccoli and related plants.
There are about 30 genes that encode bitter taste receptors in mammals. In 2003, scientists determined the sequence of the gene associated with PTC bitter tasting: taste receptor 2 member 38, or TAS2R38. This gene is 1,143 nucleotides long and has 3 locations where variations in the sequence correlate with the PTC tasting and non-tasting. Each of these changes is called a “SNP” (pronounced “snip”). A SNP is a single nucleotide polymorphism, or change in a single nucleotide in the sequence of DNA. We will use one of the SNPs to predict if you are a PTC “taster” or “non-taster.”
1 Lesson plan
Students take a Taste Inventory to determien which bitter foods they like and dislike.
Students create an initial model of humans taste bitter foods.
Students predict whether they have the SNP for the bitter taste receptor.
Students analyze their own DNA using PCR, restriction enzyme digest, and gel electrophoresis analysis to determine whether they have the SNP for bitter taste receptors.
Students analyze their own DNA using PCR, restriction enzyme digest, and MiniOne gel electrophoresis equipment to determine whether they have the SNP for bitter taste receptors.
Compiled resources for teaching about polymerase chain reaction (PCR).
These links are for SEP teachers who are part of the kit loan program. To become a part of the kit loan program you must complete the 3 week professional development program.