4. In a region of Africa, where malaria is prevalent, 40% of the population are found to have sickle-cell anemia. The disease is caused by an abnormal hemoglobin that is found in both homozygotes (S2S2) and heterozygotes (S1S2). Many homozygotes (S2S2) suffer from anemia and often die. Heterozygotes (S1S2) incur a much less debilitating malady called "sickling trait". Approximately 3% of the people with abnormal hemoglobin are homozygotes (1.2\% of the entire population). The fitness of the S2S2 homozygotes is only 1/4 that of the heterozygotes. Where malaria is prevalent, heterozygotes exhibit overdominance with respect to fitness. If we assume that the above population is at an equilibrium frequency for the allele causing sickle-cell anemia (S2), calculate the relative fitness of the S1S1 homozygotes (which have normal hemoglobin).

4. In a region of Africa, where malaria is prevalent, 40% of the population are found to have sickle-cell anemia. The disease is caused by an abnormal hemoglobin that is found in both homozygotes (S2S2) and heterozygotes (S1S2). Many homozygotes (S2S2) suffer from anemia and often die. Heterozygotes (S1S2) incur a much less debilitating malady called "sickling trait". Approximately 3% of the people with abnormal hemoglobin are homozygotes (1.2\% of the entire population). The fitness of the S2S2 homozygotes is only 1/4 that of the heterozygotes. Where malaria is prevalent, heterozygotes exhibit overdominance with respect to fitness. If we assume that the above population is at an equilibrium frequency for the allele causing sickle-cell anemia (S2), calculate the relative fitness of the S1S1 homozygotes (which have normal hemoglobin).

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter16: Human Genetics And The Human Genome

Section: Chapter Questions

Problem 6TYU

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27. Which of the following statements best explains the prevalence and geographic distribution of sickle cell anemia allele (HbS). The homozygotes for normal hemoglobin protein are always at an advantage in all environments. Homozygous recessive individuals are selected for in malarial environments. Heterozygous individuals are at a selective advantage in malarial environments. Sickle cell anemia is found in high frequencies only among West Africans and their descendants. none of the above.
2. Sickle cell disease is caused by a recessive allele. Individuals with two recessive alleles usually die of sickle cell disease before reaching reproductive age. However, individuals with only one recessive allele show few of the symptoms of the disease. The frequency of the sickle cell gene seems to be highest in populations of central Africa, a region where malaria is common. a) Do heterozygous individuals have a survival advantage over homozygous individuals in this region? Why? b) Do you think the frequency of the sickle cell allele is higher or lower in Canada as compared to Africa? Explain your answer fully.
5. Sickle cell anemia is a genetically inherited autosomal recessive trait in which results in a condition that there are not enough healthy red blood cells to carry oxygen throughout the body due to the production of red blood cells that are sickle shaped. The frequency of the sickle cell condition is as high as 10% in Central Africa compared to 0.5% in the United States. (a) Calculate the frequency of the normal and carries of the sickle cell condition. (b) (b) Malaria is a disease caused by a parasite that infects healthy red blood cells and can lead to death. However, the parasite is not able to infect sickle cell red blood cells. Scientists claim that the higher frequency of sickle cell carriers is due to the presence of malaria. Provide reasoning to support the claim.
If 9% of an African population is born with a severe form of sickle-cell anemia (ss), what percentage of the population will be more resistant to malaria because they are heterozygous (Ss) for the sickle-cell gene?
7. Red blood cells can possess a surface antigen called the Rhesus (Rh) factor. Rh+ (presence of the factor) is dominant over Rh¯ (absence). A village of population 400 was sampled and the frequency of the allele coding for Rht was found to be 0.356. a) Determine the number of individuals in the village who will be Rh b) Determine the probability of being heterozygous
BACKGROUND Sickle cell disease is caused by a change in the gene for hemoglobin, which is the oxygen-carrying protein in red blood cells. Individuals who are homozygous for the sickle cell trait often cannot endure exercise. Individuals who are heterozygous for the trait can have sickle cell attacks under extreme conditions. Normal individuals (Hb Hb) have only normal hemoglobin. Homozygous sickle cell individuals (Hb Hb') have only sickle cell hemoglobin. Heterozygous individuals (Hbs Hb) have both normal hemoglobin and sickle cell hemoglobin. Jerry Smith collapsed while running a race for his track team. A doctor said that he had a sickle cell attack. Genetic tests were run on several family members. The test results are shown below. An X indicates that form of hemoglobin in red blood cells. PROBLEM How can you determine the genotypes of people in a family? TABLE 1. FAMILY PHENOTYPES Normal Hemoglobin Subject Jerry Smith Jerry's brother Jerry's younger sister Jerry's youngest sister…
2. The common grandfather of two first cousins has hereditary hemochromatosis, a recessive condition causing an abnormal buildup of iron in the body. Neither ofthe cousins has the disease nor do any of their relatives.a. If the first cousins had a child, what is the chancethat the child would have hemochromatosis?Assume that the unrelated, unaffected parents ofthe cousins are not carriers.b. How would your calculation change if you knewthat 1 out of every 10 unaffected people in the population (including the unrelated parents of thesecousins) was a carrier for hemochromatosis?
5. A woman with type AB blood marries a man with type homozygous type B blood. What are the phenotype and genotype ratios of the offspring? 6. Hemophilia is a sex linked recessive trait. If a carrier woman marries a normal man. The couple gives birth to a boy. What are the chances that this child will have hemophilia? Make sure use XX or XY here) 7. The height of a certain plant is a result of polygenic inheritance involving two pairs of genes. Draw a Punnett square to show the result of a cross between a tall (AABB) plant and a short (aabbi. What is the phenotype ratio? 8. What is a mutation? 9. What is sickle cell anemia? 10. What is hemophilia? 11. What is a pedigree? 12. Draw a pedigree to represent the following. Shaded symbols should represent individuals with hemophilia: A man with hemophilia marries a normal woman. They have 3 children, two normal boys and a girl who is a carrier. The girl marries a normal man and they have two boys and two girls. One of the girls is a carrier…
3. In this problem you will create, and then consider, a model for the effect of influenza and pneumonia on the population of large US cities over a two-year-period. (a) The figure below is taken from [5]. Sketch on the figure, or on some axes drawn on your own page, a smooth curve that describes the “average behaviour” of the two curves shown in the figure. (b) Based on your sketch in part (a), or otherwise, make a model of the death rate due to influenza and pneumonia in large cities in the USA for the two-year-period beginning 3 August 1934. Your model should be in the form of a function. In making your model, you may have to make assumptions and/or choices. Briefly justify each assumption and choice.
3 4 6 7. In many viral diseases (e.g., smallpox, mumps and influenza), illness occurs shortly after exposure to the virus. In others (e.g., HIV AIDS), the victim may not show symptoms for many years following the initial infection. How would you explain the difference in these situations? étv %24 & 4 R T Y] F K
5.) A man and a woman living in a tropical area where malaria is prevalent and health care is not accessible have seven children during their lifetime. The genotypes of their children are: ss, Ss, SS, ss, Ss, Ss, and SS. What must the genotypes of both parents be? Your answer should include a Punnett square to illustrate your work, and list all the genotypes and phenotypes.
2. Describe the effect of the mutation that created the Hbs allele on the amino acid sequence of the beta globin polypeptide chain: effect of mutation on codon, which amino acid was changed (#amino acids from beginning of chain), what was the amino acid change (from which amino acid to which amino acid?) bmutation in the beta-globin chain affects the hemoglobin component. The