What is a test-cross? Why might a geneticist need to do a test-cross and how are the results used to determine the genotype of a specific phenotype? What differences would you expect in inheritance patterns if a trait was sex-linked versus a non-sex-linked trait?

What is a test-cross? Why might a geneticist need to do a test-cross and how are the results used to determine the genotype of a specific phenotype? What differences would you expect in inheritance patterns if a trait was sex-linked versus a non-sex-linked trait?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter5: The Inheritance Of Complex Traits

Section: Chapter Questions

Problem 2QP: The text outlines some of the problems Frederick William I encountered in his attempt to breed tall...

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Eye Color is a trait that involves a number of genes. To simplify our example, we can break down the traitinto two phenotypes: dark color and light color eyes. Dark coloration is considered dominant, or isexpressed in a heterozygous condition (when the alleles are different).Q: If you have one light eyed parent and one parent that is homozygous for dark eye color, what are thepotential eye colors of their offspring (young)? To start, what do the Parents’ alleles look like? What istheir Genotype? (Remember, you pick which letter you want to use)Light eye colored parent:Dark eye colored parent:One of the things Mendel designed was a way to provide information about how the genes are passed onfrom parent to offspring. He designed something called a Punnett Square. This square places the parents’alleles outside the box, then uses those alleles to fill in the squares.Let’s start with a reminder of what we know about the parents: Parent Phenotype(appearance) Genotype(alleles) 1 2
A cross between two pea plants, both of which grewfrom yellow round seeds, gave the following numbersof seeds: 156 yellow round and 54 yellow wrinkled.What are the genotypes of the parent plants? (Yellowand round are dominant traits.)
For Mendelian inheritance, the nuclear genotype (i.e., the allelesfound on chromosomes in the cell nucleus) directly influences anoffspring’s traits. In contrast, for non-Mendelian inheritance patterns, the offspring’s phenotype cannot be reliably predicted solelyfrom its genotype. For the following traits, what do you need toknow to predict the phenotypic outcome?A. Dwarfism due to a mutant Igf2 alleleB. Snail coiling directionC. Leber hereditary optic neuropathy
What is a reciprocal cross? Suppose that a gene is found as a wildtype (functional) allele and a recessive mutant (nonfunctional)allele. What would be the expected outcomes of reciprocal crossesif a true-breeding normal individual was crossed to a true-breedingindividual carrying the mutant allele? What would be the results ifthe gene is maternally inherited?
What is the difference between and Genotypic Trait and a Phenotypic Trait. What do each of them represent?
Let’s suppose a gene exists as a functional wild-type allele and anonfunctional mutant allele. At the organism level (i.e., at the levelof visible traits), the wild-type allele is dominant. In a heterozygote,discuss whether dominance occurs at the cellular or molecularlevel. Discuss examples in which the issue of dominance dependson the level of examination.
Describe how a biparental pattern of extranuclear inheritance couldresemble a Mendelian pattern of inheritance for a particular gene.How would they differ?
How to find the number ofpair of alleles involved inpolygenic inheritance usingthe number of phenotypicalforms of the trait theycondition?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you decide to have a child if the test results said that you carry the mutation for breast and ovarian cancer? The heart disease mutation? The TSD mutation? The heart disease and the mutant alleles?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you want to know the results of the cancer, heart disease, and TSD tests if you were Sarah and Adam? Is it their responsibility as potential parents to gather this type of information before they decide to have a child?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. If Sarah carries the mutant cancer allele and Adam carries the mutant heart disease allele, what is the chance that they would have a child who is free of both diseases? Are these good odds?
The text outlines some of the problems Frederick William I encountered in his attempt to breed tall Potsdam Guards. a. Why were the results he obtained so different from those obtained by Mendel with short and tall pea plants? b. Why were most of the children shorter than their tall parents?