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Ch. 5 - Genetic Linkage and Mapping in Eukaryotes
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 18a

The Rh blood group in humans is determined by a gene on chromosome 1. A dominant allele produces Rh+ blood type, and a recessive allele generates Rh-. Elliptocytosis is an autosomal dominant disorder that produces abnormally shaped red blood cells that have a short life span resulting in hereditary anemia. A large family with elliptocytosis is tested for genetic linkage of Rh blood group and the disease. The lod score data below are obtained for the family.
Lod score graph showing the relationship between theta values and genetic linkage for Rh blood group and elliptocytosis.
From these data, can you conclude that Rh and elliptocytosis loci are genetically linked in this family? Why or why not?

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1
Examine the graph provided, which shows the lod score plotted against recombination fraction (θ). The lod score is a statistical measure used to determine the likelihood of genetic linkage between two loci.
Identify the peak lod score on the graph. In this case, the peak lod score is approximately 6, which occurs at a recombination fraction (θ) of around 0.1.
Recall the threshold for genetic linkage: a lod score greater than 3 is considered strong evidence for linkage. Since the peak lod score is 6, this strongly suggests that the Rh blood group and elliptocytosis loci are genetically linked.
Interpret the recombination fraction (θ) value at the peak lod score. A θ value of 0.1 indicates that the loci are relatively close on the chromosome, with a 10% chance of recombination occurring between them during meiosis.
Conclude that the data supports genetic linkage between the Rh blood group and elliptocytosis loci in this family, based on the high lod score and low recombination fraction observed in the graph.

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주요 개념

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Genetic Linkage

Genetic linkage refers to the tendency of genes located close to each other on a chromosome to be inherited together during meiosis. This occurs because the physical proximity of genes reduces the likelihood of recombination between them. The strength of linkage can be assessed using lod scores, which compare the likelihood of observing the data under the hypothesis of linkage versus no linkage.
추천 영상:
가이드 코스
07:33
Chi Square and Linkage

Lod Score

A lod score (logarithm of the odds) is a statistical measure used to evaluate the likelihood of genetic linkage between two loci. A lod score greater than 3 suggests significant evidence for linkage, while a score less than -2 indicates evidence against linkage. The graph provided likely shows lod scores across different recombination fractions, helping to determine the relationship between the Rh blood group and elliptocytosis.
추천 영상:
가이드 코스
04:06
Formation of Plant Gametes

Autosomal Dominant Inheritance

Autosomal dominant inheritance is a pattern where only one copy of a dominant allele is needed for the trait or disorder to manifest. In the case of elliptocytosis, the presence of a single mutated allele leads to the abnormal red blood cell shape. Understanding this inheritance pattern is crucial for interpreting the genetic data and assessing the likelihood of the disorder being linked to the Rh blood group.
추천 영상:
가이드 코스
04:37
Variations on Dominance
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교과서 질문

In a diploid plant species, an F₁ with the genotype Gg Ll Tt is test-crossed to a pure-breeding recessive plant with the genotype gg ll tt. The offspring genotypes are as follows:

Explain the meaning of this I value.

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교과서 질문

In a diploid plant species, an F₁ with the genotype Gg Ll Tt is test-crossed to a pure-breeding recessive plant with the genotype gg ll tt. The offspring genotypes are as follows:

What is the interference value for this data set?

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교과서 질문

Genetic linkage mapping for a large number of families identifies 4% recombination between the genes for Rh blood type and elliptocytosis (see Problem 18). At the Rh locus, alleles R and r control Rh+ and Rh- blood types. Allele E producing elliptocytosis is dominant to the wild-type recessive allele e. Tom and Terri each have elliptocytosis, and each is . Tom's mother has elliptocytosis and is Rh- while his father is healthy and has Rh+. Terri's father is Rh+ and has elliptocytosis; Terri's mother is Rh- and is healthy.


What is the probability that the first child of Tom and Terri will be Rh− and have elliptocytosis?

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교과서 질문

The Rh blood group in humans is determined by a gene on chromosome 1. A dominant allele produces Rh+ blood type, and a recessive allele generates Rh-. Elliptocytosis is an autosomal dominant disorder that produces abnormally shaped red blood cells that have a short life span resulting in hereditary anemia. A large family with elliptocytosis is tested for genetic linkage of Rh blood group and the disease. The lod score data below are obtained for the family.

Over what range of θ do lod scores indicate significant evidence in favor of genetic linkage?

550
views
교과서 질문

The Rh blood group in humans is determined by a gene on chromosome 1. A dominant allele produces Rh+ blood type, and a recessive allele generates Rh-. Elliptocytosis is an autosomal dominant disorder that produces abnormally shaped red blood cells that have a short life span resulting in hereditary anemia. A large family with elliptocytosis is tested for genetic linkage of Rh blood group and the disease. The lod score data below are obtained for the family.

What is Zₘₐₓ for this family? 

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교과서 질문

The table given here lists the arrangement of alleles of linked genes in dihybrid organisms, the recombination frequency between the genes, and specific gamete genotypes. Using the information provided, determine the expected frequency of the listed gametes. Assume one map unit equals 1% recombination and, when three genes are involved, interference is zero.

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