Genetic Analysis: An Integrated Approach (3rd Edition)
3rd Edition
ISBN: 9780134605173
Author: Mark F. Sanders, John L. Bowman
Publisher: PEARSON
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Chapter 20, Problem 21P
The frequency of tasters and nontasters of PTC (see Problem
a. Calculate the frequency of the dominant (T) allele for PTC tasting and the recessive (t) allele for nontasting in each population.
b. Assuming that Hardy
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Albinos produce very little of the pigment melanin in their skin and hair. Albinism is inherited as a homozygous recessive trait. In North America, about 1 in 20,000 people are albinos.
a. What is the frequency of the dominant allele for albinism?b. What is the frequency of albinos?c. What is the frequency of heterozygotes?
In domestic chicken, feather colour and shape are two traits which are controlled by autosomal alleles that are co-dominant. Table 2 shows the alleles and phenotype of both traits. The heterozygous state for feather colour is grey while the heterozygous state for feather shape is mildly frizzled.
TABLE 2
Trait
Allele
Effect
Feather colour
CB
Produces black feathers in homozygotes
CW
Produces white feathers in homozygotes
Feather shape
SS
Produces straight feathers in homozygotes
SF
Produces frizzled feathers in homozygotes
(a)A farmer bred a black frizzled rooster with a grey mildly frizzled hen. Draw a genetic diagram to show the expected results of this cross. Include in your answer the phenotypic ratios.
(b)Is it necessary to do a test cross to determine the genotypes of the offspring? Explain your answer. (c)The farmer would like all his chickens grey and mildly…
Which of the following applies to the Hardy-Weinberg expression:p2 + 2pq + q2?a. Knowing either p2 or q2, you can calculate all the otherfrequencies.b. It applies to Mendelian traits that are controlled by one pairof alleles.c. 2pq = heterozygous individualsd. It can be used to determine the genotype and allelefrequencies of the previous and the next generations.e. All of these are correct.
Chapter 20 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
Ch. 20 - 20.1 Compare and contrast the terms in each of the...Ch. 20 - In a population, what is the consequence of...Ch. 20 - 20.3 Identify and describe the evolutionary forces...Ch. 20 - Describe how natural selection can produce...Ch. 20 - Thinking creatively about evolutionary mechanisms,...Ch. 20 - 20.6 Genetic drift, an evolutionary process...Ch. 20 - Over the course of many generations in a small...Ch. 20 - Catastrophic events such as loss of habitat,...Ch. 20 - 20.9 George Udny Yule was wrong in suggesting that...Ch. 20 - 20.10 The ability to taste the bitter compound...
Ch. 20 - Figure 20.6 illustrates the effect of an ethanol ...Ch. 20 - 20.12 Biologists have proposed that the use of...Ch. 20 - 20.13 Two populations of deer, one of them large...Ch. 20 - 20.14 Directional selection presents an apparent...Ch. 20 - 20.15 What is inbreeding depression? Why is...Ch. 20 - 20.16 Certain animal species, such as the...Ch. 20 - Genetic Analysis 20.1 predicts the number of...Ch. 20 - 20.18 In a population of rabbits, and . The...Ch. 20 - Sickle cell disease (SCD) is found in numerous...Ch. 20 - 20.20 Epidemiologic data on the population in the...Ch. 20 - The frequency of tasters and nontasters of PTC...Ch. 20 - Tay-Sachs disease is an autosomal recessive...Ch. 20 - 20.23 Cystic fibrosis (CF) is the most common...Ch. 20 - 20.24 In the mouse, Mus musculus, survival in...Ch. 20 - 20.25 In a population of flowers growing in a...Ch. 20 - Assume that the flower population described in the...Ch. 20 - 20.27 ABO blood type is examined in a Taiwanese...Ch. 20 - 20.28 A total ofmembers of a Central American...Ch. 20 - 20.29 A sample offield mice contains individuals...Ch. 20 - Prob. 30PCh. 20 - Albinism, an autosomal recessive trait...Ch. 20 - 20.32 The frequency of an autosomal recessive...Ch. 20 - 20.33 Evaluate the following pedigree, and answer...Ch. 20 - Evaluate the following pedigree, and answer the...Ch. 20 - The following is a partial pedigree of the British...Ch. 20 - Draw a separate hypothetical pedigree identifying...Ch. 20 - Prob. 37PCh. 20 - 20.38 Achromatopsia is a rare autosomal recessive...Ch. 20 - 20.39 New allopolyploid plant species can arise by...
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- In domestic chicken, feather colour and shape are two traits which are controlled by autosomal alleles that are co-dominant. Table 2 shows the alleles and phenotype of both traits. The heterozygous state for feather colour is grey while the heterozygous state for feather shape is mildly frizzled. TABLE 2 Trait Feather colour Allele CB CW SS SF Effect Produces black feathers in homozygotes Produces white feathers in homozygotes Produces straight feathers in homozygotes Produces frizzled feathers in homozygotes Feather shape A farmer bred a black frizzled rooster with a grey mildly frizzled hen. Draw a genetic diagram to show the expected results of this cross. Include in your answer the phenotypic ratios. Is it necessary to do a test cross to determine the genotypes of the offspring? Explain your answer. The farmer would like all his chickens grey and mildly frizzled. What would you advise him to do? Explain your answer.arrow_forwardCystic fibrosis (CF) is a recessive autosomal disorder. In certainpopulations of Northern European descent, the number of peopleborn with this disorder is about 1 in 2500. Assuming Hardy-Weinberg equilibrium for this trait:A. What are the frequencies for the common (non-disease-causing)allele and the mutant (disease-causing) allele.B. What are the genotype frequencies of homozygous unaffected,heterozygous, and homozygous affected individuals?C. Assuming random mating, what is the probability that twophenotypically unaffected heterozygous carriers will chooseeach other as mates?arrow_forwardFigure 19-11 shows the expected distributions for thethree genotypic classes if the B locus is a QTL affectingthe trait value.a. As drawn, what is the dominance/additive (D/A)ratio?b. How would you redraw this figure if the B locus hadno effect on the trait value?c. How would the positions along the x-axis of thecurves for the different genotypic classes of the B locuschange if D/A = 1.0?arrow_forward
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- Suppose that in unicorns, two autosomal loci interact to determine the type of tail. One locus controls whether a tail is present at all. The allele for a tail, T, is dominant over the allele for no tail, t. If a unicorn has a tail, then alleles with an unknown dominance relationship at a second locus determine whether the tail is curly or straight. Define the alleles for tail texture as U for a straight tail and U for a curly tail. S Farmer Baldridge has two unicorns with curly tails. When he crosses them, one-half of the progeny have curly tails, one-quarter have straight tails, and one-quarter do not have a tail. What are the genotypes of the parents at the tail-presence gene? TT X TT TT x tt Tt x Tt Tt x tt tt x tt What are the genotypes of the parents at the tail-texture gene? SC SC OU'U XU³UC сс OU'U' xU°U C C C C OU°UXU°Uº ƯU QU'U XU U C сс SS SS OUU³XU³U³ Place the unicorn genotype or genotypes below each unicorn phenotype in the pedigree. Some unicorn phenotypes may be the…arrow_forwardAndrogenetic alopecia (pattern baldness) is a complextrait in humans governed by several genes, but supposea human population exists in which a single autosomalallele determines pattern baldness. This allele is dominant in males and recessive in females. The population is in Hardy-Weinberg equilibrium, and 51% ofthe men are bald.a. What is the allele frequency of the baldness alleleamong males?b. What is the allele frequency of the baldness alleleamong females?c. What percentage of the women in this populationwill exhibit pattern baldness? d. Assuming random mating, what proportion of allmatings should be between a bald man and anonbald woman?e. What percentage of the bald men in the populationare heterozygotes?f. If a nonbald couple produces a bald son, what isthe probability that their next son will be bald?g. A woman with androgenetic alopecia has a daughter, but nothing is known about the father. What isthe probability that the daughter will be bald?arrow_forwardUsing the HardyWeinberg Law in Human Genetics Suppose you are monitoring the allelic and genotypic frequencies of the MN blood group locus (see Question 2 for a description of the MN blood group) in a small human population. You find that for 1-year-old children, the genotypic frequencies are MM = 0.25, MN = 0.5, and NN = 0.25, whereas the genotypic frequencies for adults are MM = 0.3, MN = 0.4, and NN = 0.3. a. Compute the M and N allele frequencies for 1-year-olds and adults. b. Are the allele frequencies in equilibrium in this population? c. Are the genotypic frequencies in equilibrium?arrow_forward
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