EBK BIOLOGY:SCIENCE F/LIFE
6th Edition
ISBN: 9780134819167
Author: BELK
Publisher: PEARSON
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Chapter 13, Problem 2AAATB
Summary Introduction
To write:
The PKU is present in the person those are homozygous recessive for this disease allele. The reasons for this disease allele can be present in various frequencies in those populations that can lead to mental retardation in homozygous person.
Introduction:
Genetic drift (allelic drift) can be defined as the variation in the frequency of an existing allele in a population due to an accidental sampling of organisms. Allele frequency of a population is the fraction of the copies of one gene which share a specific form. Reproductive isolation can be defined as the barrier created by the environment, such as a mountain range or river that does not allow mating between two groups of same species.
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Sickle cell anemia is caused by a recessive allele at a single gene. As we discussed in class, being a homozygote for the sickle cell allele is almost always lethal, but heterozygotes tend to be resistant against malaria although they have a mild form of anemia. Because of this heterozygote advantage, the allele for sickle cell anemia has a frequency of more than 10% in some human populations.
How would present allele frequencies of the sickle cell allele change, if there was no heterozygote advantage or disadvantage (that is, that heterozygotes would be identical to ‘normal’ homozygotes – no malaria resistance, no anemia)? How would the change in sickle cell allele frequencies compare to scenario a (extirpation of malaria)
The allele of the gene responsible for the lung disorder, cystic fibrosis rose to prominence in Europe in the 1800s. Cystic fibrosis disease results from thick mucus accumulating in the lungs, which occurs in individuals who are homozygous for the CF allele. A pleiotropic effect is that heterozygous individuals are less likely to suffer from diarrhea. During the European cholera epidemics of the 1800s, resistance against diarrhea conferred a survival advantage such that approximately one in every 400 people in some European populations have cystic fibrosis.
Fill in the table below with the genotype and allele frequencies for this 1 in 400 occurrence and provide the Hardy-Weinberg principle model you will be using. (Assume that individuals with the cystic fibrosis trait (CF) reproduce normally and that good sanitation means that there is currently no fitness advantage to diarrhea resistance.)
phenotype
CF
DR
normal
(totals)
Genotype
cc
Cc
CC
Number of Individuals
1
______…
Below in Figure 1 is a pedigree for a family afflicted by a genetic disorder. In some populations, Cystic fibrosis has an incidence of 1 in 2500 newborns. The carrier frequency calculated from this is 1/25. Analyze the pedigree below assuming the disease is similar to cystic fibrosis in incidence and carrier frequency. However this disease may not have the same type of genetic transmission as cystic fibrosis.
What type of genetic transmission is most consistent with the pedigree?
Label all the individuals that you can determine, with hypothesized genotypes.
Label the individuals that have unknown genotypes with possible genotypes.
Assuming her father is known to NOT be a carrier, calculate the probability that IV1 is a carrier for disease.
Use the Χ2 test to determine whether your proposed transmission fits this data.
Chapter 13 Solutions
EBK BIOLOGY:SCIENCE F/LIFE
Ch. 13 - Define biological species.Ch. 13 - Prob. 2LTBCh. 13 - Prob. 3LTBCh. 13 - Prob. 4LTBCh. 13 - Prob. 5LTBCh. 13 - Prob. 6LTBCh. 13 - The biological definition of race corresponds to...Ch. 13 - All of the following statements support the...Ch. 13 - Similarity in skin color among different human...Ch. 13 - Prob. 10LTB
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- Below in Figure 1 is a pedigree for a family afflicted by a genetic disorder. In some populations, Cystic fibrosis has an incidence of 1 in 2500 newborns. The carrier frequency calculated from this is 1/25. Analyze the pedigree below assuming the disease is similar to cystic fibrosis in incidence and carrier frequency. However this disease may not have the same type of genetic transmission as cystic fibrosis. Assuming her father is known to NOT be a carrier, calculate the probability that IV1 is a carrier for disease. Use the Χ2 test to determine whether your proposed transmission fits this data.arrow_forwardAchondroplasia is a hereditary disease with a very characteristic phenotypic manifestation. The disease is caused by a dominant allele. According to a 1986 study, the incidence of this disorder is as high as 1.5 affected per 10,000 newborns. Calculate the frequency of heterozygotes for this gene in a given population.arrow_forwardSix single-nucleotide polymorphism (SNP) loci are known to contribute to the development of type 2 diabetes. Diabetes is certain if eight or more of the alleles at these six loci are of the “contributing” variety. An uppercase letter indicates an allele that contributes to diabetes and a lowercase symbol indicates a noncontributing allele. A married couple wants to know the probability of producing a child who is at severe risk of type 2 diabetes. Their genotypes were determined by microarray analysis and are as follows: AaBbccDDEEFf × AaBbCCDdEeFfarrow_forward
- Cystic fibrosis in humans is caused by a recessive allele. A man is known to be a carrier of the cystic fibrosis allele. He marries a phenotypically normal woman. In the general population, the incidence of cystic fibrosis at birth is approximately 1 in 1,700. Assume Hardy-Weinberg proportions. What is the probability that the wife is also a carrier? Answer in decimal number only (three decimal places; example: 0.123). What is the probability that their first child will be affected? Answer in decimal number only (three decimal places; example: 0.123).arrow_forwardThe allele for sickle anemia is found at higher frequencies in central Africa than in other parts of the world. What are the advantage and disadvantages?arrow_forwardSickle 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. Calculate the frequency of the normal and carries of the sickle cell condition.arrow_forward
- Sickle Cell Anemia is caused by an abnormal form of haemoglobin, the part of the red blood cell that carries oxygen around the body. The red blood cells become stiff and block blood vessels, causing pain and damage and quickly destroying blood cells, leading to anemia. It is estimated that approximately 1 in 32 000 people in Canada are affected with sickle cell anemia.The disorder occurs when a person inherits two recessive genes for the condition. What are the frequencies of the recessive disease allele and the dominant normal allele in the population's gene pool? Select one: a. Recessive Allele Dominant Allele 0.559% 99.4% b. Recessive Allele Dominant Allele 5.59% 94.4% c. Recessive Allele Dominant Allele 0.313% 99.7% d. Recessive Allele Dominant Allele 0.00313% 99.9%arrow_forwardA mutant allele in persons with familial hypercholesterolemia (FH) causes death due to a lack of liver receptors for LDL. Susceptible persons have half the normal number of receptors, while other individuals have the normal number of receptors. In a phenotypically normal couple, the man had a female 1 cousin (on his father’s side) who died from FH; the woman had a maternal uncle with FH. Using standard symbols, draw apedigree of these couple’s families. Write the genotypes of each family member.arrow_forwardCystic Fibrosis (CF) is an autosomal recessive condition. Therefore, heterozygous (Cc) carriers do not display symptoms. Two parents who are carriers plan to start a family and you are a genetic counselor helping to advise them about their chances of having children affected by CF. a) Suppose the couple has 4 children, each one year apart. What is the probability that all 4 children will inherit CF? b) What is the probability that any 3 of their 4 children will not inherit CF, but 1 will be affected? c) What is the probability that their first child will not inherit CF, but the younger 3 children will inherit CF?arrow_forward
- 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_forwardCystic fibrosis is an autosomal recessive disease characterized by two copies of a mutated CFTR gene. If one in 100 (hypothetical scenario, not reality) people in the United States have cystic fibrosis, calculate the p and q frequency for the normal allele (p) and the mutated allele (q). Based on those calculations, what percentage of individuals would be expected to be homozygous dominant?arrow_forwardAchondroplasia is a hereditary condition caused by a dominant allele in humans (dominant allele A). This disorder affects bone growth specifically in long bones of the upper and lower limbs by preventing the ossification of bones from cartilage. Determine the genotypes of the parents and offspring for the following family scenarios in a and b below. One parent with the Achondroplasia phenotype and a normal parent have 2 children. Both children have the Achondroplasia phenotype NOTE: You must draw a Punnet square to determine the possible genotypes of te children. When two alternative genotypes are possible for an individual, indicate both.arrow_forward
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