Human Biology (MindTap Course List)
11th Edition
ISBN: 9781305112100
Author: Cecie Starr, Beverly McMillan
Publisher: Cengage Learning
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Textbook Question
Chapter 20, Problem 6CT
About 4 percent of people of Northern European descent have a cystic fibrosis allele, but only about 1 in 2,500 of these people actually has the disorder. What is the most likely reason for this finding?
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The 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?
Explain the High frequency of the sickle-cell allele HbβS in regions of Africa where malaria is prevalent?
Identify each of the following as an example of allele, genotype, and/or phenotype frequency:
A. Approximately 1 in 2500 people of Northern European descent is born with cystic fibrosis.
B. The percentage of carriers of the sickle cell allele in West Africa is approximately 13%.
C. The number of new mutations for achondroplasia, a genetic disorder, is approximately 5 × 10–5.
Chapter 20 Solutions
Human Biology (MindTap Course List)
Ch. 20 - Prob. 1RQCh. 20 - What is a carrier of a genetic trait?Ch. 20 - What evidence indicates that a trait is coded by a...Ch. 20 - Prob. 4RQCh. 20 - Explain what nondisjunction is, and give two...Ch. 20 - _______ segregate during ______. a. Homologues;...Ch. 20 - Prob. 2SQCh. 20 - Genes on the same chromosome tend to stay together...Ch. 20 - Prob. 4SQCh. 20 - A chromosomes structure can be altered by _______....
Ch. 20 - Nondisjunction can be caused by ________. a....Ch. 20 - A gamete affected by nondisjunction could have...Ch. 20 - Genetic disorders can be caused by __________. a....Ch. 20 - A person who is a carrier for a genetic trait...Ch. 20 - Prob. 10SQCh. 20 - If a couple has six boys, what is the probability...Ch. 20 - Human sex chromosomes are XX for females and XY...Ch. 20 - People with Down syndrome have an extra copy of...Ch. 20 - Prob. 4CTCh. 20 - Prob. 5CTCh. 20 - About 4 percent of people of Northern European...Ch. 20 - The following pedigree shows the pattern of...
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- Suppose we define the Alzheimer's disease phenotype as being diagnosed with the disease by age 75 years. In the human population, there are three alleles of the ApoE gene: e2, e3, e4. They form an allelic series such that: 70% of 75 year olds with the e4/e4 genotype have the Alzheimer's phenotype 60% of 75 year olds with the e3/e4 genotype have the Alzheimer's phenotype 40% of 75 year olds with the e3/e3 genotype have the Alzheimer's phenotype 30% of 75 year olds with the e2/e4 genotype have the Alzheimer's phenotype 10% of 75 year olds with the e2/e3 genotype have the Alzheimer's phenotype If I have the e4/e4 genotype and my wife has the e2/e3 genotype, what is the probability that our child will have Alzheimer's by age 75. Explain your reasoning.arrow_forwardThe 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 ______…arrow_forwardWhat would happen to the frequency of heterozygous carriers of sickle-cell anemia (with AS genotype) if mosquitoes were completely wiped out in a large region?arrow_forward
- Suppose we define the Alzheimer’s disease phenotype as being diagnosed with the disease by age 75 years. In the human population, there are three alleles of the ApoE gene: ε2, ε3, ε4. They form an allelic series such that: 70% of 75 year olds with the ε4/ ε4 genotype have the Alzheimer’s phenotype 60% of 75 year olds with the ε3/ ε4 genotype have the Alzheimer’s phenotype 40% of 75 year olds with the ε3/ ε3 genotype have the Alzheimer’s phenotype 30% of 75 year olds with the ε2/ ε4 genotype have the Alzheimer’s phenotype 10% of 75 year olds with the ε2/ ε3 genotype have the Alzheimer’s phenotype If I have the ε4/ ε4 genotype and my wife has the ε2/ ε3 genotype, what is the probability that our child will have Alzheimer’s by age 75. Explain your reasoning. [Can be answered in less than 75 words]arrow_forwardSickle 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)arrow_forwardSickle 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_forward
- Identify each of the following as an example of allele, genotype,and/or phenotype frequency:A. Approximately 1 in 2500 individuals of Northern Europeandescent is born with cystic fibrosis.B. The percentage of carriers of the sickle cell allele in WestAfrica is approximately 13%.C. The number of new mutations per generation resultingin achondroplasia, a genetic disorder, is approximately5 × 10−5.arrow_forwardSickle cell anemia is a disease that is caused by a mutation in the gene that produces hemoglobin. Hemoglobin carries oxygen in red blood cells. The HbA allele produces normal hemoglobin and the HbS allele produces hemoglobin that sticks together and causes red blood cells to sickle. Heterozygous individuals (HbAHbS) produce both normal and "sickle" hemoglobin so the HbA and HbS alleles are codominant. Heterozygotes do not develop sickle cell anemia and are described as having the sickle cell trait. Individuals that are homozygous for the sickle allele (HbSHbS) only produce "sickle" hemoglobin and develop sickle cell disease. A man with the sickle cell trait married a woman with the sickle cell trait. Determine the probability that they will have children with the sickle cell trait or sickle cell disease.Record your answer as a value between 0 and 1 rounded to two decimal places. Answerarrow_forwardWhat is the heterozygous advantage of people having sickle-cell trait in areas where malaria is a major cause of death?arrow_forward
- 2. 235O 4) Q7. Haemophiliacs possess a non-functional form of the gene responsible for the production of blood clotting factors. Shown below is the occurrence of haemophilia in one family. = male = female = male haemophiliac 7. 8. 5. 9. 3. 11 12 Usingthe following symbols: H = dominant allele h = recessive allele 1) State the genotypes of the following individuals. Individual Genotype 1. 6. 2) On the basis of the information provided, is the inheritance of haemophilia: (i) autosomal or sex-linked? (ii) dominant or recessive? 3) State the probability of individual 8 being a carrier of haemophilia. 4) Explain why only females can be carriers of haemophilia.arrow_forwardA man and a woman have a child with cystic fibrosis. Neither parent has cystic fibrosis. How could this happen? a) Both parents carry the cystic fibrosis allele, and each passed that allele to their child. b) The child had a spontaneous mutation on both copies of their CFTR alleles, leading to cystic fibrosis. c) One parent gave the child two copies of the cystic fibrosis CFTR allele. c) One parent gave the child a wild type CFTR allele, and the other parent gave them a cystic fibrosis CFTR gene.arrow_forwardIf a Mother's genotype is IAi and her Daughter's genotype is ii and the mother claims a man who is type B as the father... a) Is that possible? Explain. b) The accused man can prove that both of his parents are type AB. Is it possible for him to be type B? If so, what is his genotype? Explain. d) Does the answer in part c change the answer in part b? Explain.arrow_forward
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