MBG 2040QUIZ 2 ANSWERS.

MBG 2040 / MBG2040 QUIZ 2 ANSWERS Question 1 Inbred lines of self-fertilizing plants are typically homozygous for many genes and are often less vigorous than hybrid lines, this is referred to as: Inbreeding Depression Heterosis Hybrid vigour Allelism Question 2 Fatal Familial Insomnia is an inheritable prion disease caused by a mutation in the gene (PrPC) encoding the human prion protein (hPrP). The mutated allele (PrPSC) codes for a prion protein that replaces the typical α-helix secondary structure with a β-sheet structure. This conformational change enables the hPrP to dimerize and form the protein plaques and neuronal damage characteristic of all prion diseases. This is an example of: Haploinsuffcientcy A Gain-of-Function mutation A Loss-of-Function mutation Epistasis Question 3 Two researchers in separate labs both discover a hairless mouse, which each proves to be homozygous for a recessive mutation. In a collaboration to determine if these mutations are alleles of the same gene these researchers breed the two mice together. They discover that all of the progeny are also hairless. This suggests that: There is an epistatic relationship between the two genes controlling hairlessness in mice Hairlessness is actually a dominant trait These mutations are alleles of the same gene The two separate genes controlling the presence of hair in mice are linked Question 4 The degree to which a trait is manifested in each individual is called the: Expressivity Penetrance Variability Variable Dominance Question 5 Polymorphic Dominant Codominant Question 6 The proportion of individuals with a particular genotype that the express the expected phenotype is called _ _. Penetrance Variable Dominance Expressivity Variability Question 7 While studying the inheritance of leaf length in a particular plant you cross a true breeding short leaf plant to a true breeding long leaf plant and find that all of the F1 progeny have intermediate leaf lengths. This is most likely an example of: Incomplete Dominance Codominance Incomplete Penetrance Variable Expressivity Quiz 2:ML Question 8 A woman with Type A blood and a man with Type B blood have a child with Type AB blood, what is the probability that a second child will also be Type AB? 50% 25% 100% Not enough information is given in the question Dominance Series and Pedigrees Question 9 In a specific species of cattle, coat patterning is controlled by two epistatic genes. Individuals that have at least one dominant gene C allele (C/-) will be white regardless of the genotype for Gene S. Individuals homozygous recessive for Gene C with at least one dominant allele for Gene S (ccS/-) it will be white with brown spots. Double heterozygotes (ccss) will be white with black spots. Given the pedigree above, where open shapes represent white cattle, shaded shapes represent brown spotted cattle and solid black shapes represent black spotted cattle, what are the genotypes of I-1 and I-2? Ccs- x Ccs- Ccss x Ccss C-ss x C-Ss ccSS x CCss HW Question 10 If a rare recessive single gene genetic disorder occurs at a rate of 1/49900 in a given population, use Hardy-Weinberg principle to estimate the frequency of the recessive allele. Round to 4 decimal places. Your Answer: (0.0045) Question 1 Plants that are heterozygous for many genes tend to grow larger and out compete plant of the same species with less genetic variability. This phenomenon is know as: Haplosuffciency Complementation Gain-of-Function Inbreeding Depression Question 2 Cystic Fibrosis (CF) is caused by mutations in the CFTR gene which result in the production of a non-functional transmembrane ion channel. Individuals who are heterozygous for this gene (CFTRcftr) will not have CF as one copy of the wildtype gene is sufficient to produce enough of the functional ion channels to maintain health. Marfan’s Sydrome is caused by mutations in the fibrillin-1 producing gene FBN1. The mutated allele (fbn1) codes for a non- functional fibrillin-1 protein. Individuals that are heterozygous for this gene (FBN1fbn1) do not produce enough functional fibrillin-1 to maintain health and thus will manifest with Marfan’s syndrome. Both of these diseases are an example of: Haploinsufficiency Gain-of-Function mutations Haplosufficiency Question 3 When two alleles appear to contribute to a trait independently where neither alleles is completely or even partially dominant over the other they exhibit: Incomplete Dominance A dominance series Complete Dominance Question 4 Two researchers in separate labs both discover a hairless mouse, which each proves to be homozygous for a recessive mutation. In a collaboration to determine if these mutations are alleles of the same gene these researchers breed the two mice together. This cross is referred to as a: Dihybrid cross Epistatic Test Monohybrid cross Question 5 A single gene that influences several aspects of a phenotype is said to be: Dominant An allele Polymorphic Question 6 A change in a phenotype produced by environmental factors that mimics the phenotype of a mutant organism is called a: Polymorphism Genocopy Pleiotropy Question 7 The gene responsible for producing the A and B blood antigens has three alleles, IB, IA and i which each exist in significant frequencies. This is an example of: Pleiotropic Dominance Series Quiz 2:ML Question 8 You are studying flavour in a specific variety of tomato. While most of the plants produce a sweet tomato, occasionally you come across either bitter or very tart tomatoes. Based on what you know about flavour in fruiting plants you hypothesize that this trait is determined by two enzymes that catalyze the breakdown of a very bitter molecule. In your proposed model each of these enzymes is produced by a gene that exhibits complete dominance, that is that only one copy of the wildtype allele is required for complete conversion. Because Gene X controls the first step in the pathway, if the genotype is xx, the phenotype will be bitter, regardless of the phenotype in Gene Y. This is referred to as: Complete Dominance Dominant Epistasis Dominance Series and Pedigreesk Question 9 In a specific species of cattle, coat patterning is controlled by two epistatic genes. Individuals that have at least one dominant gene C allele (C/-) will be white regardless of the genotype for Gene S. Individual homozygous recessive for Gene C with at least one dominant allele for Gene S (ccS/-) it will be white with brown spots. Double heterozygotes (ccss) will be white with black spots. Given the pedigree above, where open shapes represent white cattle, shaded shapes represent brown spotted cattle and solid black shapes represent black spotted cattle, what are the genotypes of I-1 and I-2? C- S- x CcS- HW Question 10 CCss x ccSS CCss x ccS- Cc- - x ccS- If a recessive allele has a frequency of 0.0958 in given population, use Hardy-Weinberg principle to estimate the percentage of individuals who would be expected to have the recessive phenotype. DO NOT ENTER THE PERCENTAGE SIGN; round to one decimal place. Your Answer: (0.9) Question 1 The gene associated with the recessive disorder Cystic Fibrosis (CFTR) produces a transmembrane cellular chloride channel. Multiple alleles for this gene exist, some of which contain mutations that render this channel non-functional. An individual with two mutated alleles will have Cystic Fibrosis. However, an individual that is heterozygous for the wildtype and mutated alleles will not have symptoms as one healthy copy of this gene will produce enough of the Chloride channel to maintain appropriate function. This is an example of: Haploinsufficiency Incomplete Penetrance Haplosufficiency A Gain-of-Function mutation Question 2 When one allele completely masks the presence of another different allele it is said to exhibit: Incomplete Dominance Codominance Complete dominance Complementation Question 3 When the heterozygote phenotype is an intermediate between the two corresponding homozygote phenotypes the alleles exhibit: Codominance Complete Dominance Complementation Incomplete Dominance Question 4 Marfan's Syndrome is a dominant genetic disease caused by mutations in the fibrillin-1 producing gene FBN1. When mutated this gene produces non-functional fibrillin-1, a major component of the extracellular matrix. Individuals that are heterozygous for the wildtype FBN1 allele and the mutated fbn1 allele do not produce enough functional fibrillin-1 to maintain health and thus will manifest with Marfan's syndrome; a disease characterized by connective tissue disorders. This is an example of: Polymorphism A Gain-of-Function mutation Haploinsufficiency Haplosufficiency Question 5 When the same phenotype can be produced by a number of different mutations in separate genes it is said to be: A Heterozygous Trait Pleiotropic A Heterogenous Trait Polymorphic Question 6 When two or more independently assorting genes influence a phenotype and the presence of one of the gene alleles has an overriding effect or masks the presence of the other alleles it is said to be: Polymorphic Dominant Epistatic Codominant Question 7 Cystic Fibrosis (CF) is caused by mutations in the CFTR gene which result in the production of a non-functional transmembrane ion channel. Individuals who are heterozygous for this gene (CFTRcftr) will not have CF as one copy of the wildtype gene is sufficient to produce enough of the functional ion channels to maintain health. Marfan’s Sydrome is caused by mutations in the fibrillin-1 producing gene FBN1. The mutated allele (fbn1) codes for a non- functional fibrillin-1 protein. Individuals that are heterozygous for this gene (FBN1fbn1) do not produce enough functional fibrillin-1 to maintain health and thus will manifest with Marfan’s syndrome. Both of these diseases are an example of: Loss-of-Function mutations Haploinsufficiency Gain-of-Function mutations Haplosufficiency Quiz 2:ML Question 8 Consider two independently assorting genes that both produce the same phenotype in the homozygous recessive state. You cross two such individuals. aaBB x AAbb What phenotypes would you expect from this cross? All progeny would exhibit the wildtype phenotype 3:1; wildtype:recessive phenotypes 1:1; wildtype:recessive phenotypes All progeny would exhibit the recessive phenotype Dominance Series and Pedigrees Question 9 In a particular species of fish the gene that controls tail patterning has multiple alleles that exhibit a dominance series. The allele for a crescent mark on the tail (tc) is dominant over all other alleles, while the alleles for one (t1) and two (t2) spots on the tail are both dominant over the allele for no spots (t0). However (t1) and (t2) alleles exhibit codominance where heterozygotes (t1t2) have three spots. A crescent fish of unknown genotype is bred to a 3 spotted fish. You observe only the crescent, one spot and two spot phenotypes in the F1 generation. If you were to record the numbers for each phenotype what ratios would you expect? 12:3:1; crescent: two spots: one spot HW Question 10 12:3:1; crescent: one spot: two spots 1:1:1; Crescent: one spot: two spots 3:1; Crescent: two spots 2:1:1; crescent: one spot: two spot If a rare recessive single gene genetic disorder occurs at a rate of 1/11600 in a given population, use Hardy-Weinberg principle to estimate the frequency of the dominant allele. Round to 4 decimal places. Your Answer: (0.9907) Question 1 When the same phenotype can be produced by a number of different mutations in separate genes it is said to be: Polymorphic A Heterogenous Trait Pleiotropic A Heterozygous Trait Question 2 Marfan's Syndrome is a dominant genetic disease caused by mutations in the fibrillin-1 producing gene FBN1. When mutated this gene produces non-functional fibrillin-1, a major component of the extracellular matrix. Individuals that are heterozygous for the wildtype FBN1 allele and the mutated fbn1 allele do not produce enough functional fibrillin-1 to maintain health and thus will manifest with Marfan's syndrome; a disease characterized by connective tissue disorders. This is an example of: Haplosufficiency A Gain-of-Function mutation Haploinsufficiency Polymorphism Question 3 Two researchers in separate labs both discover a hairless mouse, which each proves to be homozygous for a recessive mutation. In a collaboration to determine if these mutations are alleles of the same gene these researchers breed the two mice together. This cross is referred to as a: Monohybrid cross Epistatic Test Complementation Test Dihybrid cross Question 4 The proportion of individuals with a particular genotype that the express the expected phenotype is called _ _. Penetrance Expressivity Variable Dominance Variability Question 5 The gene associated with the recessive disorder Cystic Fibrosis (CFTR) produces a transmembrane cellular chloride channel. Multiple alleles for this gene exist, some of which contain mutations that render this channel non-functional. An individual with two mutated alleles will have Cystic Fibrosis. However, an individual that is heterozygous for the wildtype and mutated alleles will not have symptoms as one healthy copy of this gene will produce enough of the Chloride channel to maintain appropriate function. This is an example of: A Gain-of-Function mutation Haploinsufficiency Incomplete Penetrance Haplosufficiency Question 6 The gene responsible for producing the A and B blood antigens has three alleles, IB, IA and i which each exist in significant frequencies. This is an example of: Dominance Series Allelism Pleiotropic Polymorphism Question 7 A single gene that influences several aspects of a phenotype is said to be: Pleiotropic An allele Dominant Polymorphic Quiz 2:ML Question 8 While studying snapdragon plants, you notice that seedlings are either green or yellow. You hypothesize that this phenotype is controlled by one gene with two alleles, in which green (G) is dominant over yellow (g). You cross two green heterozygote plants (Gg x Gg) and observe the following phenotypes. Phenotypes of F1 Snapdragons Green Yellow 207 96 What phenomenon best explains these results? Complete dominance Incomplete Dominance Epistasis Recessive Lethal Dominance Series and Pedigrees Question 9 In a species of finch, tail feather colour is controlled by two epistatic genes. Birds that have at least one dominant allele for both genes, P- Y-, will have pink tail feathers. Birds that are homozygous recessive for one of the genes, P-yy or ppY-, have yellow tail feathers. Double homozygous recessive, ppyy, birds have white tail feathers. Given the pedigree above where the tail feathers of each individual are indicated by the colour of the shape, what are the genotypes of individuals I-1 and I-2? ppYy x Ppyy ppYY x PPyy ppYy x ppYy Ppyy x Ppyy HW Question 10 If a rare recessive genetic disorder occurs at a rate of 1/1100 in a given population, use Hardy-Weinberg principle to estimate what percentage of this population are carriers of the recessive allele. DO NOT ENTER THE PECENTAGE SIGN. Example: if your answer is 10.5% enter it as 10.5; one decimal place. Your Answer: (5.8)