Based on previous family studies, an autosomal recessive disease ...

Question

Based on previous family studies, an autosomal recessive disease with alleles A and a is suspected to be linked to an RFLP marker. The RFLP marker has four alleles, R₁, R₂, R₃, and R₄. The accompanying pedigree shows a three-generation family in which the disease is present. The gel shows the RFLP alleles for each family member directly below the pedigree symbol for that person. After determining the genotypes for the RFLP and disease gene for each family member, answer the following questions.

Based on your analysis, what is the recombination frequency in this family? Explain how you obtained your answer.

Accepted Answer

Hey, everyone. Let's take a look at this question together in a study of A P plant. Researchers have identified two genes A and B located on the same chromosome. A di hybrid plant that is heterozygous for both genes is crossed with a homozygous recessive plant. The following offspring were obtained 250 heterozygous for both genes. 250 heterozygous for A but homozygous recessive for B 50 are homozygous recessive for A and heterozygous for B and 50 are homozygous recessive for both genes, which of the following are the genotypes of the recombinant. And so our answer choices contain different combinations of each of the genotypes of the offspring. And we are looking for the answer choice that contains the genotypes of both of the recombinant. So let's work this problem out together to try to figure out what the genotypes are for the recombinant P plants. And in order to figure out which ones are the recombinant from the following offspring, we must first identify the parent genotypes, which we know that we have one parent who is heterozygous for both genes and has that heterozygous A and heterozygous B genotype. So our first parent genotype is heterozygous for both genes. And we know that the other parent is homozygous recessive for both genes. So we have the other parent is homozygous recessive for both A and B, which means that the 250 offspring that are heterozygous is one parent genotype and the 50 that are homozygous recessive for both A and B is the other parent, which means that the other two genotypes are the genotypes of our recombinant. So, the recombinant, you know types R, heterozygous A homozygous recessive B and also Homozygous recessive A and heterozygous B, which means that answer choice. D homozygous recessive A and heterozygous B as well as heterozygous A and Homozygous recessive B are the two genotypes of the recombinant. So it is the correct answer since we know that the parent genotypes are heterozygous for both A and B as well as homozygous recessive for both A and B making the other two genotypes of the offspring. Those recombinant genotypes, which we note the recombinant genotypes are heterozygous A and homozygous recessive B as well as Homozygous recessive A and heterozygous B, which is answer choice. D, the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

Autosomal Recessive Inheritance

Restriction Fragment Length Polymorphism (RFLP)

Recombination Frequency

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