Suppose you have high sensitivity to tasting PTC. If your...

Key Concepts

Genotype Uncertainty

Given that you and your mother both taste PTC, the existence of the dominant allele is confirmed in each of you. However, the father’s genotype cannot be definitively predicted because the necessary allele for tasting could have been inherited solely from the mother. Thus, even if he were a non-taster with a recessive genotype, it would not affect the offspring’s phenotype if the dominant allele was provided by the other parent.

Dominant Allele Expression

PTC tasting is an example of a trait determined by a dominant allele. This means that an individual only needs one copy of the taster allele to exhibit the ability to taste PTC. As a result, even if only one parent contributes the dominant allele, the offspring can display the trait, complicating predictions about the other parent's genotype based solely on the offspring's phenotype.

Mendelian Inheritance

This concept explains that many traits are inherited in a predictable manner according to Mendel’s laws, where alleles segregate and assort independently. In the context of PTC tasting, the ability is typically controlled by a gene with two alleles, one of which is dominant. This framework helps us understand how traits are passed down from parents to offspring.

Transcript

00:01 So for this question, it's important to see what you can deduce using the information that you have.

00:06 So we know that we are talking about the ptc gene.

00:09 Now, this gene is involved in taste and tasting a very specific herb.

00:13 So if you have the dominant allele for this gene, at least one dominant allele, you will be able to taste the herb as bitter.

00:20 And if your homozygous recessive, if you have two recessive alleles, that means you will not be able to taste the herb.

00:27 So i'm going to have a capital t in this case represent being able to taste the herb, and then a lowercase tea represent not being able to taste the herb.

00:41 And the question tells you that you are highly sensitive and able to taste this herb.

00:48 This means that you have to be either homozygous dominant or heterozygous because you only need one dominant allele in order to taste the herb.

00:59 You also know that your mother is also highly sensitive and able to taste this herb.

01:06 And that means she's the same.

01:07 She's either homozygous dominant or heterozygous.

01:11 Now based off of this information, can you tell what the father's genotype is? so you could draw out all of the punnet squares for this.

01:21 And so looking at this, we're going to see if we can narrow down any of the answers for the father's genotype.

01:29 So the father can either be homozygous dominant, heterozygous, or homozygous recessive...

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