What are the possible phenotypes of a man both of whose parents are tasters?

The ability to taste a bitter chemical, phenylthiocarbamide (PTC), is due to a dominant allele. In terms of tasting ability, what are the possible phenotypes of a man both of whose parents are tasters? What are his possible genotypes, is it possible that he could be a non-taster? (Use T for the allele for tasting ability, and t for the allele for the absence of the ability to taste PTC.). Now set up Punnet squares with ALL the possible parental genotypes and resulting offspring genotypes.

I'd appreciate any and all help. Thank you ^_^.

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  • Paul
    Lv 6
    8 years ago
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    Since both parents are tasters, the dominant phenotype, they each could be homozygous dominant (TT) or heterozygous (Tt). So when you set up the Punnett squares you need to set up three of them. One for the case when both parents are homozygous dominant (TT x TT) in which case all the children are also homozygous dominant. A second Punnett square for the case where you have one of each parent (TT x Tt), offspring a mix of TT and Tt. The third Punnett square is for both heterozygous parents (Tt x Tt), offspring a mix of all genotypes. In this case he could be either phenotype.

    Source(s): I teach biology.
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