Loose-leaf Version for What Is Life? A Guide to Biology 4E & LaunchPad for What is Life? A Guide to Biology 4E (Twelve Month Access)
4th Edition
ISBN: 9781319154639
Author: Jay Phelan
Publisher: W.H. Freeman & Co
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Chapter 9, Problem 9MC
Summary Introduction
Introduction:
Phenylketonuria is characterized by the build-up of phenylalanine in cells.
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Which pathology leads to an increased risk of Alzheimer’s disease?
Select one:
a. Accumulation of the Amyloid β peptide
b. Homozygosity for the e2 ApoE allele
c. Sedentary lifestyle in young adulthood
d. A mutation in the presenilin 4 gene
e. Increase in blood cholesterol
In a study, an undergraduate student discovered a new enzyme involved in the metabolism of
serotonin. This enzyme is made up of 3 subunits of the same protein. To characterize this
enzyme, the student used genetic approaches to induce mutations in the coding region of the
gene that codes for this protein and performed crosses to measure the effects of genotypes on
enzyme activity.
A) Indicate directly in the diagram (via a bar graph) the predicted relationship between
genotype and enzyme activity. (Al represents the wild-type allele, A2 represents the
mutant allele).
A2A2
A1A2
A1Α1
B) Explain the reasoning for your prediction.
Enzyme Activity
Which of the following scenarios best describes an epistatic gene?
Select one:
a. Fur pattern is controlled by two genes such that one gene inhibits the expression of the other gene.
b. Chicken combs follow a dominance hierarchy whereby a walnut comb is the most dominant and a single comb is the least dominant.
c. Individuals with sickle cell anemia and carriers of the sickle cell allele have some resistance to malaria.
d. Mouse fur colours are expressed as a blend of the dominant black colour and the recessive white colour, resulting in a heterozygous brown colour.
Chapter 9 Solutions
Loose-leaf Version for What Is Life? A Guide to Biology 4E & LaunchPad for What is Life? A Guide to Biology 4E (Twelve Month Access)
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- For gain-of-function disorders, which of the following treatment strategies is the be . A. Gene augmentation B.Supply healthy cells . C.Supply normal form of proteins encoded by wild-type allele . D. Gene silencingarrow_forwardWhich of the following experimental observations suggest that adisease has a genetic basis?A. The frequency of the disease is less likely in relatives that liveapart compared with relatives that live together.B. The frequency of the disease is unusually high in a small groupof genetically related individuals who live in southern Spain.C. The disease symptoms usually begin around the age of 40.D. It is more likely that both monozygotic twins will be affectedby the disease than will dizygotic twins.arrow_forwardWhich of the following statements describes an example of a phenocopy? Explain your reasoning. a. Phenylketonuria results from a recessive mutation that causes light skin as well as intellectual disability. b. Human height is influenced by genes at many different loci. c. Dwarf plants and mottled leaves in tomatoes are caused by separate genes that are linked. d. Vestigial wings in Drosophila are produced by a recessive mutation. This trait is also produced by high temperature during development. e. Intelligence in humans is influenced by both genetic and environmental factors.arrow_forward
- a. Which gene is mutated in individuals with sickle-cell anemia? b. What are the major symptoms of this disorder? c. What was the first published scientific description of sickle-cell anemia? d. Describe two other features of this disorder that you learned from the OMIM database and state where in the database you found this informationarrow_forwardAlbinism is characterized by the lack of a dark pigment called melanin in the hair, skin and eyes. Albinism is caused by the absence of an functioning enzyme called thyrosinase, which is necessary for the synthesis of melanin. Given this bit of information, what can you assume about the heredity pattern of this trait? A) It is caused by a recessive allele of the gene coding for thyrosinase. B) It is caused by a dominant allele of the gene coding for melanin. C) It is caused by a dominant allele of the gene coding for thyrosinase. D) It is caused by a recessive allele of the gene coding for melanin. E) There is not enough information here to tellarrow_forwardGlucose-6-phosphate dehydrogenase (G6PD) is a critical enzyme involved in the metabolism of glucose,especially in red blood cells. Deficiencies in the enzymeare the most common human enzyme defect and occurat a high frequency in certain populations of East Africanchildren.a. Offer one hypothesis for the high incidence of G6PDmutations in East African children.b. How would you test your hypothesis further?c. Scores of different G6PD mutations affecting enzyme function have been found in human populations.Offer one explanation for the abundance of differentG6PD mutations.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_forwardAlzheimer’s is a progressive neurological disorder resulting in dementia and memory loss that occurs in 10% of the US population older than 65. In the 1990s, several researchers showed evidence that the allele of a cholesterol precursor gene, APO E4, increased risk of developing the disorder compared to APO E2 or APO E3. This was especially pronounced if patients carried two alleles of APO E4. However, not all people with APO E4 develop the disorder and some without it will present with Alzheimer's nevertheless. This suggests other genes influence development of the disease. Current research has elucidated dozens of genes that interact with APO E4 pathways in hundreds of ways. As many as 27 of the interactions are epistatic, with some as dominant epistasis and some as recessive epistasis. In addition, some of the gene candidates for non-APO E4 Alzheimer’s have other relationships such as dominant, codominant or incomplete dominant. No reliable cure currently exists for Alzheimer’s…arrow_forwardAlzheimer’s is a progressive neurological disorder resulting in dementia and memory loss that occurs in 10% of the US population older than 65. In the 1990s, several researchers showed evidence that the allele of a cholesterol precursor gene, APO E4, increased risk of developing the disorder compared to APO E2 or APO E3. This was especially pronounced if patients carried two alleles of APO E4. However, not all people with APO E4 develop the disorder and some without it will present with Alzheimer's nevertheless. This suggests other genes influence development of the disease. Current research has elucidated dozens of genes that interact with APO E4 pathways in hundreds of ways. As many as 27 of the interactions are epistatic, with some as dominant epistasis and some as recessive epistasis. In addition, some of the gene candidates for non-APO E4 Alzheimer’s have other relationships such as dominant, codominant or incomplete dominant. No reliable cure currently exists for Alzheimer’s…arrow_forward
- Retinitis pigmentosa, a group of related eye disorders that cause progressive vision loss, is due to an autosomal dominant allele. Tay-Sachs disease, on the other hand, is due to a defective gene with incomplete dominance. A mutation in the recessive HEXA gene prevents the synthesis of the lysosome enzyme beta-hexosaminidase A. This mutation prevents the breakdown of GM2 ganglioside, thus increasing to a toxic level that damages neurons. Luisa is a carrier of the allele for Tay-Sachs but has no sign of any eye disorder in her family. She married Gerard whose mother was afflicted with retinitis pigmentosa, unlike his father. Neither of his parents has any history of Tay-Sachs disease. What are the genotypes of Luisa and Gerard? Luisa:______________________________Gerard:_____________________________arrow_forwardRetinitis pigmentosa, a group of related eye disorders that cause progressive vision loss, is due to an autosomal dominant allele. Tay-Sachs disease, on the other hand, is due to a defective gene with incomplete dominance. A mutation in the recessive HEXA gene prevents the synthesis of the lysosome enzyme beta-hexosaminidase A. This mutation prevents the breakdown of GM2 ganglioside, thus increasing to a toxic level that damages neurons. Luisa is a carrier of the allele for Tay-Sachs but has no sign of any eye disorder in her family. She married Gerard whose mother was afflicted with retinitis pigmentosa, unlike his father. Neither of his parents has any history of Tay-Sachs disease. What are the genotypes of Luisa and Gerard? Luisa:______________________________Gerard:_____________________________ 2. If they plan to have five children, what is the probability that: all their children will be normal? _________________________________ they will have a daughter…arrow_forwardWhich of the following statements does NOT describe an environmental influence on the expression of a gene? Select one: a. Siamese cats have darkened paws, nose, and tip of tail due to a gene that allows their skin and fur to darken in the parts of their bodies that need to retain more heat, their extremities. b. More than a single gene is involved in the expression of human height, weight, and skin colour. c. Exposure to sunlight increases melanin production in human skin. d. Colder incubation temperatures of gecko eggs yield more females and warmer temperatures yield more males.arrow_forward
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