Concept explainers
Tay-Sachs disease is an autosomal recessive neurological disorder that is fatal in infancy. Despite its invariably lethal effect, Tay
a. What is a genetic bottleneck?
b. Explain how a genetic bottleneck and its aftermath could result in a population that carries a lethal allele in high frequency
c. In the population described, what is the frequency of the recessive allele that produces Tay
d. Assuming mating occurs at random in this population, what is the probability a couple are both carriers of Tay
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Genetic Analysis: An Integrated Approach (2nd Edition)
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- In parts of equatorial Africa, where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the ß-hemoglobin alleles in the human gene pool. The sickle cell trait provides an advantage against malaria compared to people with normal hemoglobin. In the United States, the parasite that causes malaria is not present, but African Americans whose ancestors were from equatorial Africa have the sickle-cell B- hemoglobin allele. These differences in traits illustrate O inclusive fitness because people have evolved molecular differences to adapt to environmental stimuli O inclusive fitness because ß-hemoglobin increases the proliferation of beneficial traits in the population O relative fitness because people have evolved molecular differences to an environmental pathogen O relative fitness because the molecular differences in ß-hemoglobin are passed to the next generationarrow_forwardSickle-cell anemia is a recessive disease that afflicts approximately 1 in 12 African Americans, meaning that the frequency of ss homozygotes is 0.09. Assuming the African American population is in Hardy-Weinberg equilibrium, what is the frequency of Ss carriers in this population?arrow_forwardThe eugenic movement was created in the early 20th century by Sir Francis Galton. Its aim was to improve the genetic pool of the human population by selective breeding. One idea was to discourage individuals with Mendelian autosomal recessive diseases to have children. However, the fallacy of this idea is shown by the fact that recessive lethal alleles (that are never found in homozygosity) can persist in populations for hundreds to thousands of generations. Which one of the following statements best explains the persistence of those alleles in populations? There is heterozygote advantage in those populations. Recessive alleles keep being produced by mutation. Recessive alleles cannot be selected against when present in heterozygotes. Genetic drift keeps recessive alleles at a relative high frequency in populations. Consider the action of mutation and of genetic drift in a population. What do you expect genetic variation will be in a…arrow_forward
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