Human Biology (MindTap Course List)
11th Edition
ISBN: 9781305112100
Author: Cecie Starr, Beverly McMillan
Publisher: Cengage Learning
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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?
Cystic fibrosis is an autosomal recessive disorder that affects 1 in 3 000 newborns with Caucasian background. It causes thick mucus build up in various organs and can cause damages and problems in respiratory and digestive systems.
a) What is the frequency of the cystic fibrosis allele in the Caucasian population? Show all your work and express your answer as a value between 0 and 1 rounded to two decimal places.
b) What percentage of the Caucasian population would be carriers for cystic fibrosis? Show all your work and express your answer rounded to two decimal places.
c)If two individuals are carriers of the cystic fibrosis allele, what is the probability that they would have a girl without cystic fibrosis? Show all your work (including the Punnett square) and express your answer as a value between 0 and 1 rounded to two decimal places.
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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- 1. What are the symptoms of sickle cell disease (anemia)? 2. What is the genotype of sickle cell disease? Use these sources to find the answers: https://ghr.nlm.nih.gov/condition/sickle-cell-disease#inheritance https://www.cdc.gov/ncbddd/sicklecell/traits.htmlarrow_forwardWhat is heterozygote advantage. How does this phenomenon explain the preponderance of disorders such as cystic fibrosis and sickle cell anemia ?arrow_forwardWhat is the frequency of sickle cell disease (anemia)? https://ghr.nlm.nih.gov/condition/sickle-cell-disease#inheritance https://www.cdc.gov/ncbddd/sicklecell/traits.htmlarrow_forward
- What 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_forwardIdentify 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_forward2. STATEMENT: A woman and man both do not have sickle-cell anemia, but both had one parent who had sickle cell. Sickle-cell is an autosomal (somatic) recessive trait. a) What is the genotype for the woman, man and each of their parents? b) This couple unexpectedly is going to have their first child. i. What's the probability that their child will have not have sickle cell like the couple? ii. What's the probability that the child will have sickle cell like one the grandparents?arrow_forward
- We often speak of diseases such as phenylketonuria (PKU) andachondroplasia as having a genetic basis. Explain whether the followingstatements are accurate with regard to the genetic basis ofany human disease (not just PKU and achondroplasia).A. An individual must inherit two copies of a mutant allele to havedisease symptoms.B. A genetic predisposition means that an individual has inheritedone or more alleles that make it more likely that she or he willdevelop disease symptoms than other individuals in a populationwill.C. A genetic predisposition to develop a disease may be passedfrom parents to offspring.D. The genetic basis for a disease is always more important thanthe environment.arrow_forwardIn Huntington’s disease, the wild-type allele, h, is recessive to the disease allele, H. The persistence of an autosomal dominant allele that is fatal in 100% of cases is best explained by which of the following? A) The dominant allele only has moderate negative effects during adolescence and young adulthood. B) The wild-type h allele continues to spontaneously mutate into the dominant H allele. C) The persistence of any given allele in nature is determined almost wholly by chance. D) The disease has no effects until the individual has reached an age far past the normal age for reproduction.arrow_forwardOver a thousand different alleles at the CFTR locus have been discovered that can cause cystic fibrosis. What difficulties might the presence of so many different alleles at this locus create for the diagnosis and treatment of cystic fibrosis?arrow_forward
- Hypophosphatemia (vitamin D-resistant rickets) is inherited as a sex-linked dominant trait (H). A) A normal woman and a man with hypophosphatemia marry. What is the chance of having daughters with rickets? Sons? B) A heterozygous woman and a normal man marry. Does the mother have rickets? What is the chance of having daughters with rickets? Sons?arrow_forwarda) A woman who is type A has a daughter who is type O. Give the genotypes of both the mother and of the daughter. b) The mother claims a man who is type B is the father. Is that possible? Explain. c) 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? d) Does the answer in part c change the answer in part b?arrow_forwardWhat is sickle cell anemia? What is the true inheritance pattern? How did scientists discover the true inheritance pattern?arrow_forward
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