ESSENTIALS OF GENETICS-W/MOD.ACCESS
9th Edition
ISBN: 9780134452876
Author: KLUG
Publisher: PEARSON
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Chapter 21, Problem 22PDQ
While most quantitative traits display continuous variation, there are others referred to as “threshold traits” that are distinguished by having a small number of discrete
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Chapter 21 Solutions
ESSENTIALS OF GENETICS-W/MOD.ACCESS
Ch. 21 -
CASE STUDY | A genetic flip of the coin
On July...Ch. 21 - CASE STUDY|A genetic flip of the coin On July 11,...Ch. 21 -
CASE STUDY|A genetic flip of the coin
On July...Ch. 21 - HOW DO WE KNOW?
1. In this chapter, we focused on...Ch. 21 - Review the Chapter Concepts list on page 422....Ch. 21 -
3. Define the following: (a) polygenic, (b)...Ch. 21 - A dark-red strain and a white strain of wheat are...Ch. 21 - Height in humans depends on the additive action of...Ch. 21 -
6. An inbred strain of plants has a mean height...Ch. 21 - Prob. 7PDQ
Ch. 21 - In the following table, average differences of...Ch. 21 - What kind of heritability estimates (broad sense...Ch. 21 - List as many human traits as you can that are...Ch. 21 - Corn plants from a test plot are measured, and the...Ch. 21 -
12. The following variances were calculated for...Ch. 21 - The mean and variance of plant height of two...Ch. 21 - A hypothetical study investigated the vitamin A...Ch. 21 - In a herd of dairy cows the narrow-sense...Ch. 21 - In an assessment of learning in Drosophila, flies...Ch. 21 - Suppose you want to develop a population of...Ch. 21 -
18. In a population of tomato plants, mean fruit...Ch. 21 - In a population of 100 inbred, genotypically...Ch. 21 - In a cross between a strain of large guinea pigs...Ch. 21 - While most quantitative traits display continuous...
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- A pedigree analysis was performed on the family of a man with schizophrenia. Based on the known concordance statistics, would his MZ twin be at high risk for the disease? Would the twins risk decrease if he were raised in an environment different from that of his schizophrenic brother?arrow_forwardPedigree 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?arrow_forwardPedigree 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?arrow_forward
- 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?arrow_forwardWhich of the following statements about complex traits is/are TRUE? Twin studies help to tease apart the contribution of genetic and environmental factors to phenotypic variations. When describing quantitative traits, a high variance indicates that most individual values are not very close to the mean. Genetic factors determine Mendelian traits, while environmental factors determine complex traits. Both additive and dominant effect falls in the category of narrow sense heritability and can be directly passed on from parents to offspring.arrow_forwardHeight in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci R, S, T, and U and that environmental effects are negligible. Instead of additive versus nonadditive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute two units, and partially additive alleles contribute one unit to height. (a) Can two individuals of moderate height produce offspring that are much taller or shorter than either parent? If so, how? (b) If an individual with the minimum height specified by these genes marries an individual of intermediate or moderate height, will any of their children be taller than the tall parent? Why or why not?arrow_forward
- If the frequency of those exhibiting a monogenic autosomal recessive phenotype caused by a rare clinically relevant allele is 1/8500 in a given population, what is the carrier frequency? Please give your answer as a percentage to 3 decimal places, do not include the % symbol. ANSWER: In a population where the frequency of those exhibiting a monogenic autosomal recessive phenotype caused by only one known mutation is 1/8500 the carrier frequency is a percent.arrow_forwardFor each of the following characteristics, indicate whether it would be considered a discontinuous characteristic or a quantitative characteristic. Briefly justify your answer. a. Kernel color in a strain of wheat, in which two codominant alleles segregating at a single locus determine the color. Thus, there are three phenotypes present in this strain: white, light red, and medium red. b. Body weight in a family of Labrador retrievers. An autosomal recessive allele that causes dwarfism is present in this family. Two phenotypes are recognized: dwarf (less than 13 kg) and normal (greater than 23 kg). c. Presence or absence of leprosy. Susceptibility to leprosy is determined by multiple genes and numerous environmental factors. d. Number of toes in guinea pigs, which is influenced by genes at many loci. e. Number of fingers in humans. Extra (more than five) fingers are caused by the presence of an autosomal dominant allele.arrow_forwardQTL mapping and GWA (association) mapping are two different methods used to identify genes that affect complex traits. For each of the following statements, choosewhether it applies to QTL mapping, association mapping, or both.whether it applies to QTL mapping, association mapping, or both.arrow_forward
- For the following five questions, A = true, and B = false 18. (2 pts) The dominance of an allele may vary for different traits. 19. (2 pts) Loss-of-function alleles are recessive, not dominant. 20. (2 pts) A haplosufficient allele is able to produce a wild-type phenotype in the heterozygous state. 21. (2 pts) The permissive temperature, which is usually lower than the normal growth temperature, is the temperature at which a mutant phenotype becomes observable. 22. (2 pts) In a cross between two true-breeding recessive mutants that are affected in different genes, the proportion of F1 progeny that show complementation (the wild-type phenotype) is affected by the map distance between the two genes.arrow_forwardin considering the interaction of multiple genes involved in complex traits and interaction with the environmental factors what does the organisms genotype represent? What does the phenotype represent? What does the environment have to do with it?arrow_forwardHow does heritability differ between major trait categories such as morphology, life history, behavior, and physiology? Which trait types are generally most heritable and which are least heritable?arrow_forward
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