Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 21, Problem 12P
| a. | Alleles of genes on the X chromosome can also be at equilibrium, but the equilibrium frequencies under the Hardy-Weinberg assumptions must be calculated separately for the two sexes. For a gene with two alleles A and a at frequencies of p and q, respectively, write expressions that describe the equilibrium frequencies for all the genotypes in men and women. |
| b. | Approximately 1 in 10,000 males in the United States is afflicted with hemophilia, an X-linked recessive condition. If you assume that the population is at Hardy-Weinberg equilibrium, what proportion of American females would be hemophiliacs? About how many female hemophiliacs would you expect to find among the 170 million women living in the United States? (Assume that all females with hemophilia are homozygous for the disease allele.) |
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Chapter 21 Solutions
Genetics: From Genes to Genomes
Ch. 21 - Choose the best matching phrase in the right...Ch. 21 - When an allele is dominant, why does it not always...Ch. 21 - A population with an allele frequency p of 0.5 and...Ch. 21 - In a certain population of frogs, 120 are green,...Ch. 21 - Which of the following populations are at...Ch. 21 - A dominant mutation in Drosophila called Delta...Ch. 21 - A large, random mating population is started with...Ch. 21 - Prob. 8PCh. 21 - Alkaptonuria is a recessive autosomal genetic...Ch. 21 - Two hypothetical lizard populations found on...
Ch. 21 - It is the year 1998, and the men and women sailors...Ch. 21 - a. Alleles of genes on the X chromosome can also...Ch. 21 - In 1927, the ophthalmologist George Waaler tested...Ch. 21 - The equation p2 2pq q2> = 1 representing the...Ch. 21 - A gene has two alleles A frequency = p and a...Ch. 21 - Some people can taste the bitter compound...Ch. 21 - Androgenetic alopecia pattern baldness is a...Ch. 21 - The following figure shows the FBI-style analysis...Ch. 21 - Why is the elimination of a fully recessive...Ch. 21 - Tristan da Cunha is a group of small islands in...Ch. 21 - Small population size causes genetic drift because...Ch. 21 - Three basic predictions underlie genetic drift in...Ch. 21 - A mouse mutation with incomplete dominance t =...Ch. 21 - In Drosophila, the vestigial wings recessive...Ch. 21 - In a population of infinite size, three loci A, B,...Ch. 21 - You have identified an autosomal gene that...Ch. 21 - In Europe, the frequency of the CF allele causing...Ch. 21 - An allele of the G6PD gene acts in a recessive...Ch. 21 - Explain why evolutionary biologists monitor...Ch. 21 - Tiny foxes live on the Channel Islands off the...Ch. 21 - What is the most straightforward evidence at the...Ch. 21 - In March 2013, the American Journal of Human...Ch. 21 - If you go back 40 generations into your biological...Ch. 21 - In Fig. 21.17, to what part of the world does...Ch. 21 - Predict the DNA sequences at the four nodes...Ch. 21 - A cladogram not drawn to scale for the taxonomic...Ch. 21 - As noted in Fig. 21.22, humans now living in...Ch. 21 - As of this writing in 2016, no Neanderthal-derived...
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- a. Two linked biallelic loci (c = 0.1) have allele frequencies pA = 0.7 and pB = 0.4. If these two sites are in linkage disequilibrium with D = -0.12, what are the expected haplotype frequencies under these conditions? b. What will the linkage disequilibrium parameter D be after 20 generations?arrow_forwardstion 6 of 18 Suppose that a geneticist discovers a new mutation in Drosophila melanogaster that causes the flies to shake and quiver. She calls this mutation quiver, qu, and determines that it is due to an autosomal recessive gene. She wants to determine whether the gene encoding quiver is linked to the recessive gene for vestigial wings, vg. She crosses a fly homozygous for quiver and vestigial traits with a fly homozygous for the wild-type traits, and then uses the resulting F, females in a testcross. She obtains the flies from this testcross. Phenotype Number of flies vg* qu+ 230 vg qu 224 vg qut vg* qu 97 99 Test the hypothesis that the genes quiver and vestigial assort independently by calculating the chi-squared, X², for this hypothesis. Provide the X2 to one decimal place. X2 = Does the X value support the hypothesis that the quiver and vestigial genes assort independently? Why or why not? the partial table of critical values for X2 calculations to test this hypothesis.arrow_forwardGive the genotypic frequencies expected under the Hardy–Weinberg law for (a) an autosomal locus with three alleles and (b) an X-linked locus with two alleles.arrow_forward
- a. Determine the gene order, the recombination frequency between the adjacent genes, the coefficient of coincidence, and the interference. b. Explain why, in this example, the recombination frequencies are not good estimates of the map distance.arrow_forwardConsider the MN blood system in humans. This blood system consists of only two alleles, M and N, and they are codominant to each other. Three genotypes are possible, and these genotypes can be easily identified through simple blood typing procedures, including the heterozygous MN due to the codominant mode of inheritance. Consider the following data: Phenotype Genotype Number of individuals M MM 89 MN MN 162 N NN 79 1. How many alleles exist in this population? 2. What is the genotypic frequency of the M blood type in the population? 3. What is the allelic frequency of M? 4. What is the allelic frequency of N? 5. What is the genotypic frequency of MN? Write your answers directly. You do not need to show your solution.arrow_forwardOne particularly useful feature of the Hardy-Weinberg equation is that it allows us to estimate the frequency of heterozygotes for recessive genetic diseases, assuming that Hardy-Weinberg equilibrium exists. As an example, let’s consider cystic fibrosis, which is a human genetic disease involving a gene that encodes a chloride transporter. Persons with this disorder have an irregularity in salt and water balance. One of the symptoms is thick mucus in the lungs that can contribute to repeated lung infections. In populations of Northern European descent, the frequency of affected individuals is approximately 1 in 2500. Because this is a recessive disorder, affected individuals are homozygotes. Assuming that the population is in Hardy-Weinberg equilibrium, what is the frequency of individuals who are heterozygous carriers?arrow_forward
- A. Clearly there is significant genetic variation associated with susceptibility to COVID-19. Does that mean that the heritability of COVID-19 susceptibility is close to 1? Based on your knowledge, what is the potential role of the environment in determining susceptibility to COVID-19? B. What is the utility of understanding the genetic basis of susceptibility to COVID-19 for medicine and public health? Can you think of potential applications of this knowledge?arrow_forwardKernel color in wheat Red kernel color in wheat results from the interaction between two dominant alleles. With only one dominant allele, the phenotype is brown while in the absence of any dominant allele, the phenotype is white. Suppose that plants of a variety that is true breeding for red kernels are crossed with plants true breeding for white kernels. What specific type of interaction can be observed? A. duplicate dominant genes B. duplicate genes with cumulative effects C. complementary genes D. dominant epistasis (case 2)arrow_forwardSuppose there is an autosomal locus of 2 alleles, A1 and A2, with probabilities (frequencies) p1 and p2, and the genotype probabilities (frequencies) are P(A1A1) = p1*p1, P(A1A2) = 2*p1*p2, and P(A2A2) = p2*p2, respectively. Prove the Hardy-Weinberg Law, i.e., after one generation of random mating, the genotype probabilities (frequencies) in the offspring are also P(A1A1) = p1*p1, P(A1A2) = 2*p1*p2, and P(A2A2) = p2*p2. Hint: List all possible combinations of random mating. Then list the probabilities of the resulting genotype probabilities (frequencies) in the offspring. Combine the probabilities of random mating and resulting genotype probabilities (frequencies) in the offspring.arrow_forward
- Due to dosage compensation by X inactivation, females can exhibit a mosaic pattern of sweat glands on only some portions of their body if they carry a particular loss of function allele. Could any of the following genotypes result in males with such a mosaic pattern of sweat glands? Explain. A. X^AY B. X^AX^AY C. X^AX^aY D. Not possiblearrow_forwardThis Manhattan plot shows the results of a GWAS investigation of prostate cancer risk. Select which of the statements below could be TRUE based on the data provided. Select ALL that apply 4, Chromosome а. The Y axis is the strength of association between prostate cancer and the variant. b. The spike at the end of Chr 6 indicate the presence of a low risk allele for breast cancer. O c. There are 6 SNPS that are associated with increased risk for prostate cancer. O d. The low heritability of prostate cancer makes GWAS an excellent tool for understanding prostate cancer risk. O e. The X axis represents any loci in the genome with variation. -Hog10 (P)arrow_forward1. For a single locus with two alleles, A₁ and A₂: (a) Draw a graph (using graph paper) showing both the frequency of A₁ A2 heterozy- gotes and A₂ A₂ homozygotes, at Hardy-Weinberg frequencies, as functions of p (the frequency of A₁). Note that both p and the genotype frequencies should have values between 0 and 1. (b) Find the value of p above which A₁ A2 genotypes are more common than A₂42 genotypes. You can solve this algebraically, or estimate it from your graphs. 2. Consider three loci, A, B, and C, each with two alleles, with the frequencies of A₁, B₁, and C₁ all being We look at a population and find that there are four distinct haplotypes, shown here, each with a frequency of: A₁ B1 TT A1 C₁ B1 A₂ B₂ AT C₂ A₂ B₂ C₁ C₂ Of the three pairs of loci (AB, AC, and BC) which pair(s) are in Gametic Equilibrium (D = 0) and which are in Gametic Disequilibrium (D ‡0)? [Hint: Consider each pair separately, ignoring the other locus. For example: for the BC pair, consider the four…arrow_forward
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