Question

What are the 3 possible allele combinations for PTC tasting?

Answer 1

PTC tasting is largely determined by a single gene, TAS2R8, with two common alleles, and the allele for tasting is mostly dominant over the allele for non-tasting. However, both classical family and twin studies, and modern molecular genotyping, show that there are other genes or environmental factors that influence PTC tasting. As a result, there is a continuous range of PTC tasting, not absolute separation into tasters and non-tasters. PTC tasting would be a fascinating subject for an advanced genetics class, but it does not fit the one-gene, two-allele myth well enough to be used to demonstrate simple Mendelian genetics.

Answer 2

Answer:

Inability to taste PTC is sometimes described as an autosomal recessive trait: persons with the TT or Tt genotypes have the "taster" phenotype, persons with the tt genotype have the "non-taster" phenotype. The "non-taster" phenotype is therefore described as a "recessive" trait.