ESSENTIALS OF GENETICS MCC BUNDLE >BI<
9th Edition
ISBN: 9781323915370
Author: KLUG
Publisher: PEARSON
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Chapter 21, Problem 1PDQ
HOW DO WE KNOW?
In this chapter, we focused on a mode of inheritance referred to as quantitative genetics, as well as many of the statistical parameters utilized to study quantitative traits. Along the way, we found opportunities to consider the methods and reasoning by which geneticists acquired much of their understanding of quantitative genetics. From the explanations given in the chapter, what answers would you propose to the following fundamental questions:
(a) How can we ascertain the number of polygenes involved in the inheritance of a quantitative trait?
(b) What findings led geneticists to postulate the multiple-factor hypothesis that invoked the idea of additive alleles to explain inheritance patterns?
(c) How do we assess environmental factors to determine if they impact the
(d) How do we know that monozygotic twins are not identical genotypically as adults?
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For a specific example, you might assume that four members of this pedigree are albinos: the woman in the first generation, her second daughter (the mother of individuals 5, 6, 7, and 8), and individuals 4 and 11 in the third generation. Now, assume that you are a genetic counselor and that individuals 6 and 12 in the third generation of this pedigree come to you and ask, “What is the probability that if we marry and have a family, an albino child will be born to us?”
The counselor must determine the probability that individuals 6 and 12 are heterozygous carriers of the recessive gene for albinism. The counselor must also consider the probability of two heterozygous carriers producing a homozygous recessive child. First of all, the mother of individual 6 is an albino (cc), which means that 6 must be (probability = 1 or 100%) a heterozygote. The father of individual 12 must be heterozygous (Cc) since his mother is an albino. Although individual 12 is not an albino, he has a ½ chance of…
Chapter 21 Solutions
ESSENTIALS OF GENETICS MCC BUNDLE >BI<
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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- 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?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. 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_forwardPedigree Analysis Is a Basic Method in Human Genetics Using the pedigree provided, answer the following questions. a. Is the proband male or female? b. Is the grandfather of the proband affected? c. How many siblings does the proband have, and where is he or she in the birth order?arrow_forward
- What is the difference between a Mendelian multifactorial trait and a polygenic multifactorial trait?arrow_forwardA study of SNPs associated with familial hypercholesterolemia has revealed that 7 or more contributing alleles at 6 loci can lead to elevated levels of cholesterol in the blood. What is the probability that the following parents, AaBbccDDeeFF x AAbbCCDdEeFF, will have children that are susceptible to hypercholesterolemia?arrow_forwardAside from the Punnett square, are there other ways to understand the inheritance of traits in humans, animals and/or plants? Give at least one and describe if there is.arrow_forward
- Individuals, such as Ryan Clark and Geno Atkins, heterozygous for the sickle cell allele show effects of the allele under some circumstances (refer to the linked article and Mendelian patterns of inheritance in your text). Explain in terms of gene expression. http://www.nfl.com/news/story/0ap3000000714754/article/coleman-unsure-on-denver-game-due-to-sickle-cell-traitarrow_forwardA study of three generations in a family of a male colleague of the authors indicated that many of the man's blood relatives had died of cardiovascular accidents and coronary heart disease. Others died of other causes but were affected by high blood pressure. What are the implications of this information for the man in question? b. What information and help might a genetic counselor provide?arrow_forwardin own understanding, what is mendelian genetics?arrow_forward
- Why Geneticists Use a Variety of Symbols for Alleles ? What are those ?arrow_forwardExplain, at the molecular level, why human genetic diseases oftenfollow a simple Mendelian pattern of inheritance, whereas mostnormal traits, such as the shape of your nose or the size of yourhead, are governed by multiple gene interactions.arrow_forwardTotal fingerprint ridge count exemplifies a polygenic inheritance pattern. Penrose (1969) and others have suggested that a minimum of seven gene loci contribute to TRC, but a four-locus model is hypothesized in the problems that follow. Thus, AABBCCDD represents the genotype for maximum ridge count and aabbccdd symbolizes the genotype for the minimum ridge count. Assume that each active allele adds 15 ridges to the TRC of the male and 12 to the TRC of the female and that having the genotype aabbccdd produces a baseline TRC of 70 for males and 50 for females. Predict the TRC for each of the following individuals: Genotype Male Female AABBCCDD AabbccDd AaBBCcDD aaBbCCDd A. Write the genotypes of parents who are heterozygous for all four genes. B. Write the genotype of their child who has the maximum number of active alleles possible. C. What are the TRCs for the parents? D. What is the TRC of the child from B (assume male)?…arrow_forward
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