Concept explainers
Epidemiologic data on the population in the previous problem reveal that before the application of modern medical treatment, natural selection played a major role in shaping the frequencies of alleles. Heterozygous individuals have the highest relative fitness, and in comparison to heterozygotes, those who are
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GENETIC ANALYSIS: AN INTEG. APP. W/MAS
- The prevalence (frequency) of sickle-cell disease in Canada is quite low, affecting 1/3800 individuals. However, in some African populations 1/25 individuals are affected by sickle-cell disease. The difference in frequency of this allele within the differing populations has to do with the adaptation pressures that exist in the different environments. Individuals with the heterozygous genotype have a survival advantage in environments where the disease malaria is prevalent as the presence of this mutant allele leads to resistance to malaria. Therefore, the sickle-cell disease tends to be more frequent in environments where the malaria parasite is most common. Question: Explain why the sickle-cell disease remains frequent in some populations while it exists in very low frequency in other populations.arrow_forwardYou have collected and determined genotypes of 200 individuals from a population of thr fruit fly, Drosophila pseudoobscura. Your sequencing study revealed 20 individuals with genotype AA, 70 individuals with genotype Aa and 110 individuals with genotype aa. i) what are your theoretical expectations for the number of individuals with each genotype if the population is in Hardy-Weinberg equilibrium. ii) Based on the genotype counts observed, is there evidence that this population of fruit flies deviates from your theoretical expectations under Hardy-Weinberg equilibrium?arrow_forwardAn allele of the G6PD gene acts in a recessive manner to cause sensitivity to fava beans, resulting in ahemolytic reaction (lysis of red blood cells) afteringestion of the beans. The same allele also confersdominant resistance to malaria. The heterozygote hasan advantage in a region where malaria is prevalent.Will the equilibrium frequency (qe) be the same foran African and a North American country? Whatfactors affect qe?arrow_forward
- A sample of 100 individuals from a population that is dimorphic at the A locus has genotype counts as follows. AA: 30 Aa: 60 aa: 10 a) What are the allele frequencies in the population? b) What are the expected genotype frequencies, if the population were at HardyWeinberg equilibrium? c) Is the proportion of heterozygotes lower or higher than expected at Hardy-Weinberg equilibrium? What deviations from the assumptions of the model would best explain the observed difference?arrow_forwardIf a disease determined by autosomal recessive heredity occurs at a frequency of 0.04 in a population, what is the frequency of this disease allele in the population? Assume Hardy-Weinberg equilibrium and use Aand a to symbolize the dominant and recessive alleles, respectively. Show calculation.arrow_forwardYou are a scientist studying a population of beetles. Beetle color is controlled by two alleles at a single genetic locus. AA beetles are blue, Aa purple, and aa pink. You count 30 blue beetles, 10 purple beetles, and 40 pink beetles. a) What is the frequency of the A allele? [ Select ] b) What is the observed frequency of the Aa genotype? 1 Select ] c) Under Hardy-Weinberg equilibrium, what is the expected frequency of the aa gentoype? [ Select ] d) Is this beetle population evolving? I Select ]arrow_forward
- An autosomal locus has alleles A and a. The allele frequencies in a population at Hardy Weinberg equilibrium are p = Freq(A) = 0.5 q = Freq(a) = 0.5 What is the frequency of homozygous wild-type (AA) in this population? Enter a single number between 0 and 1, for example, 0.33arrow_forwardplease tell us the expected average time to fixation of an allele at frequency p = 0.5 in a population of 100 individuals, we can safely assume that the allele does become fixed?arrow_forwarda.)If the frequency of an allele at a locus of interest is 0.57, what is the frequency of the genotype that is homozygous for this allele (that is, that genotype has two copies of this allele)? b.) If we know that the frequency of an allele at a locus of interest is 0.57, we have enough information to calculate the frequency of the related phenotypes in the population, assuming there are only two alleles.arrow_forward
- ln a population of turtles, there are yellow-green shells and green shells. The yellow shells are caused by a homozygous recessive gene and the green shells are caused by the dominant gene. Given the following data:AA = 340Aa = 270aa = 120 a) Calculate p and q. b) Use a chi square test to determine if these alleles are in Hardy-Weinberg equilibrium. Submit your answer as a pdf or doc file. Show your workarrow_forwardWhat is the expected genotype frequency of the heterozygous genotype under the Hardy-Weinberg equation P = 0.7?arrow_forwardA population of wookies is polymorphic for the fur color, which is controlled by two loci. 230 have black hair, 64 have brown hair, and 32 have yellow hair. You test suspect that the epistatic interactions between the two loci are reponsible for this ratio and wish to test that hypothesis using a X^2 test. a) What is the most likely epistasis? b) Complete the following X^2 table. For the first three columns, enter your answer as intergers with no demical points. For the last column, enter your answer to two deimal points e.g 4.36 Fur Observed Expected O-E (O-E)^2 (O-E)^2/E Black 240 Brown 64 yellow 32 total 336 X^2arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning