The accompanying pedigree shows a family in which one ch...

Question

The accompanying pedigree shows a family in which one child (II-1) has an autosomal recessive condition. On the basis of this fact alone, provide the following information.

What is the chance that among the three children in generation II who have the dominant phenotype, one of them is AA and two of them are Aa? (Hint: Consider all possible orders of genotypes.)

Accepted Answer

Hi, everyone. Let's look at our next question. It says which of the following best describes the below mentioned pedigree. And we have a pedigree here with two generations labeled Roman numeral one and Roman numeral two generation one. We just have to individuals, the parents labeled one and two. And then in generation two, we have four offspring, two male, two female, one male affected, one, unaffected, one female, unaffected and one female affected. So let's look through our answer choices. Now, choice A says the pedigree shows the inheritance of an illness in three successive successive generations. Well, this answer is not correct because we only have two generations in this pedigree. Not three. So choice A is incorrect. Choice B says in the pedigree to individuals, Roman numeral 2-1 and Roman numeral 2-4 are affected. Well, this is correct, Roman Road to our second generation, we have to affected individuals labeled number one and number four. Um You can tell they're affected because they're shaded in black. Um or as unaffected individuals are left unshaded, they look white. So choice B is our correct answer. So we'll highlight that. Let's look next to choice. See, the pedigree shows the inheritance of A Y linked treat. Well, this is not correct because we do have an affected female In our pedigree. That individual Roman rule 2-4 is an effective female. Um, a wildling trait you'd only see affected males because females don't have a Y chromosome. So choice C is incorrect. And then finally choice D the pad agree shows the inheritance as an autism, all dominant trait. Well, this is not correct because we have affected Children whose parents are unaffected. So there's two affected individuals in generation to um but neither of the parents are affected by autism. All dominant traits. Every affected child will have an affected parent because you only need one copy of the alil to express the condition. So if they inherited from the parent, the parent must express the condition. So this would show an autism, a recessive trait since the two unaffected parents must be hetero six carriers of the recessive trait. So choice D is not correct. So again, which of the following best describes the below mentioned pedigree Choice B in the pedigree to individuals, Roman numeral 2-1 and Roman numeral 2-4 are affected. See you in the next video.

Key Concepts

Autosomal Recessive Inheritance

Genotype Probability

Combinatorial Probability

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