Suppose 64 percent of a remote mountain village can taste phenylthiocarbamide (PTC) and must, therefore, have at least one copy of the dominant PTC taster allele. If this population conforms to Hardy-Weinberg expectations for this gene, what percentage of the population must be heterozygous for this trait?

Question

Quizplus · Accepted Answer

To find the percentage of the population that is heterozygous for the PTC taster allele, we first need to determine the allele frequencies. If 64% can taste PTC, this means 64% have at least one dominant allele (T). The frequency of the taster phenotype (TT or Tt) is 0.64, and thus the frequency of the non-taster phenotype (tt) is 1 - 0.64 = 0.36. The square root of 0.36 gives the frequency of the recessive allele (t), which is 0.6. Therefore, the frequency of the dominant allele (T) is 1 - 0.6 = 0.4. The frequency of heterozygotes (2pq) can be calculated as 2(0.4)(0.6) = 0.48, or 48%.

Suppose 64 Percent of a Remote Mountain Village Can Taste