Bio 312, Spring 2017 Exam 3 ( 1 ) Name: Please write the first letter of your last name in the box; 5 points will be deducted if your name is hard to read or the box does not contain the correct letter. Written answers should be concise and precise; answers typically have short correct answers. Regrade requests cannot be made for exams completed in pencil for any reason. The exam has 100 points total 1. MUTATION:SELECTION BALANCE. Genetic diseases arise from the segregation of deleterious alleles. These are usually recessive, but in rare cases they are co-dominant or dominant. Consider a hypothetical genetic variant, "a", which researchers find is associated with reduced rates of fertility compared to individuals with the wildtype "A" allele. Studies show that individuals that are homozygous for this allele have only 90% the normal rate of reproduction due to decreased fertility. Assume for the questions below that the per generation mutation rate that creates this deleterious allele is 10-6 (approximately correct for single locus) and that the population of the world is approximately 6,000,000,000. (a, 3 pts) If the deleterious allele is recessive, what is the predicted frequency of this allele in the population? (Provide answer to 3 significant figures) (b, 3 pts) If the deleterious allele is recessive, what is the expected number of people experiencing this disorder (i.e., homozygotes) in the world? (c, 3 pts) If the deleterious allele is recessive, what is the expected number of "carriers" for this disorder (i.e., heterozygotes) in the world? (d, 3 pts) If the deleterious allele is dominant, what is the predicted frequency of this allele in the population? (Provide answer to 3 significant figures) (e, 3 pts) If the deleterious allele is dominant, what is the expected number of people homozygous people experiencing this disorder in the world? (f, 3 pts) If the deleterious allele is dominant, what is the expected number of people heteroozygous people experiencing this disorder in the world? f(a) = # affected = # carriers = f(a) = # affected = # carriers =
Bio 312, Spring 2017 Exam 3 ( 2 ) Name: 2. EFFECTIVE POPULATION SIZE. (provide answers to nearest 0.01) (a, 3 pts) What is the mean census population size of a population that cycles between 400, 500 and 600 members on alternate years? N= (b, 3 pts) What is the effective population size of a population that cycles between 400, 500 and 600 members on alternate years? Ne= (c, 3 pts) What is the census population size of a population that has 200 males and 700 females? N= (d, 3 pts) What is the effective population size of a population that has 200 males and 700 females? Ne= 3. EVOLUTIONARY RATES. (provide answers to nearest 0.0001) Consider a situation in which the homozygote for an advantageous allele (AA) experiences a 4% fitness advantage over the other homozygote (aa) and the frequency of the advantageous allele is p=0.3. (a, 3 pts) If the "A" allele is dominant, what is the frequency of the allele in the next generation? p' = (b, 3 pts) If the "A" allele is co-dominant (h=1/2), what is the frequency of the allele in the next generation? p' = (c, 3 pts) If the "A" allele is recessive, what is the frequency of the allele in the next generation? p' =
Bio 312, Spring 2017 Exam 3 ( 3 ) Name: 4. POPULATION GENETICS. Consider a population of 5000 cats at Hardy-weinberg equilibrium with two polymorphic loci that each have two alleles: - One locus controls how much the tongue sticks out and the population possesses two alleles; one dominant allele that confers a "blep" effect whereby the tongue sticks out (see picture below) and a recessive one that confers a normal "non-blep" tongue. - One locus controls pelage pattern and the population possesses two co-dominant alleles; Homozygotes for the "solid" allele have a solid pattern, homozygotes for the "stripe" allele have a striped pattern and heterozygotes have a patchy pattern. (a, 3 pts each) If a " blep" cat with a solid color pattern is mated with a "non-blep" cat with a patchy pattern, what proportion of the offspring have a patchy pattern? (provide answer to nearest whole percent) % patchy = Now assume that the two loci are in linkage equilibrium and the number of individuals of each penotype are as follows: Blep & solid pelage = 408 Blep & patchy pelage = 1224 Blep & striped pelage = 918 Non-blep & solid pelage = 392 Non-blep & patchy pelage = 1176 Non-blep & striped pelage = 882 (b, 3 pts each) What are the frequencies of each of the alleles? (provide answers to nearest 0.001) Freq. of "blep" allele = Freq. of "non-blep" allele = Freq. of "solid" allele = Freq. of "stripe" allele =
Bio 312, Spring 2017 Exam 3 ( 4 ) Name: 5. MOLECULAR EVOLUTION FILL IN THE BLANKS (1 pt each = 18 pts total) Consider the evolutionary process from a molecular perspective. Thinking about a single locus, initially every individual in the population has the same allele so each individual is and we would say that the population is at that locus. If, due to random factors, a mutation changes an adenine to a cytosine at the locus we would call it a mutation and that individual is now heterozygous. If that mutation would result in lower fitness for homozygotes, but not heterozygotes we would call it and. If the allele isn't lost due to genetic drift it may increase in frequency and become common; at that point we would refer to it as a. In time the allele may even increase in frequency and in the population, creating a new population in which all individuals have two copies of the new allele at the locus. When this change in the entire population occurs we term this change a. If the nucleotide change alters an amino acid we say the nucleotide change is and if the new amino acid is very different in size or charge from the original we would say that the amino acid change is a one. If this process is driven by positive selection, then the nearby loci are likely to experience a in their ; identifying such regions in genomes can therefore be used to locate regions of recent selection. If this process is driven entirely by genetic drift then the scenario fits the one described in the theory of molecular evolution as proposed by Motoo which predicts A constant rate of evolution per. This theory was later amended by his protégé Tomoko Ohta because data showed that evolutionary rates were constant per instead. Whatever the details, this constant rate allows us to develop something called the which can be used to date evolutionary events using molecular data.
Bio 312, Spring 2017 Exam 3 ( 5 ) Name: FOR THE REMAINING QUESTIONS USE YOUR SCANTRON FORM MULTIPLE CHOICE: (2 pts each). For the next two questions consider a large mainland population with two alleles, Bt and Hk, at a locus which are present in equal frequency in a large mainland population. (1) This mainland begins to send migrants to a nearby island on which the Bt allele is present at 25% of the loci. If after the first generation of this process the new frequency of the Bt allele on the island is 27%, which of the following values is closest to the immigration rate to the island? (A) 0.02% (B) 2% (C) 4% (D) 8% (E) 16% (2) If this migration process were to continue for 6 more generations, which of the following values is closest to the frequency of the Bt allele on the island after that amount of time? (A) 27.9% (B) 32.4% (C) 34.8% (D) 40.2% (E) 41.2% (3) The technical term for a population in which any individual can mate with any other, without geographic factors or distance being important, is which of the following (A) Epistatic (C) Overdominant (E) Perturbed (B) Normal (D) Panmictic (4) The Haldane-Muller principle is best paraphrased by which of the following? (A) The rate of mutation is constant over time. (B) The rate of substitution, per year, is constant. (C) The rate of substitution, per generation, is constant. (D) The effects of deleterious mutations on individuals depend only on their rate, not on the fitness effect. (E) The effects of deleterious mutations on population mean fitness depend only on their rate, not on the fitness effect. (5) Which type of genetic data is the best to use for distinguishing individuals within a population from one another? (A) Frameshift polymorphisms (D) Presence or absence of indels (B) Microsatellite repeat variants (E) Radical amino acid polymorphisms (C) Polymorphisms in exons For the next two questions consider a situation in which an isogenic diploid population has 5000 individuals and a generation time of 5 years. Suddenly, a new neutral allele arises by mutation. (6) Which of the following is closest to the probability that it will fix and become the wildtype allele in the future? (A) 0.0001 (C) 0.0003 (E) 0.0005 (B) 0.0002 (D) 0.0004 (7) If this novel alleles fixes and becomes the new wildtype allele, which of the following is closest to how long would this take? (A) 10,000 years (C) 25,000 years (E) 200,000 years (B) 20,000 years (D) 100,000 years
Bio 312, Spring 2017 Exam 3 ( 6 ) Name: For the next two questions consider a cross between an AABbccDD and an aabbccdd individual where the alleles at the loci influence a quantitative trait. (8) How many different genotypes can result from the cross? (A) 2 (B) 3 (C) 4 (D) 5 (E) 6 (9) Assume that the effects of the different alleles at each locus are identical with regard to increasing (capital letter) or decreasing (lower case letter) the trait. Assume also that alleles represented with capital letters are dominant to those represented by lower case ones and each locus has the same effect on the phenotype. How many different phenotypes can result from the cross? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5 For the next two questions consider a cross between an AaBbCc and an AaBbCc individual where the alleles at the loci influence a quantitative trait. (10) How many different genotypes can result from the cross? (A) 3 (B) 6 (C) 9 (D) 18 (E) 27 (11) Assume that the effects of the different alleles at each locus are identical with regard to increasing (capital letter) or decreasing (lower case letter) the trait. Assume also that all the alleles are co-dominant and each locus has the same effect on the phenotype. How many different phenotypes can result from the cross? (A) 1 (B) 3 (C) 5 (D) 7 (E) 9 The following 3 questions are based upon the videos you watched in preparation for this exam. (12) Which of the following best describes the worldwide distribution of lactose intolerance? (A) About 33% of all people are lactose intolerant with the highest levels of intolerance in Africa. (B) About 33% of all people are lactose intolerant with the highest levels of intolerance in Asia. (C) About 33% of all people are lactose intolerant with the highest levels of intolerance in Europe. (D) About 66% of all people are lactose intolerant with the highest levels of intolerance in Asia. (E) About 66% of all people are lactose intolerant with the highest levels of intolerance in Europe. (13) Throughout the video "lactose tolerance" is referred to with which of the following phrases? (A) Lactase intolerance (C) Lactose intolerance (E) Milk digestion (B) Lactase persistence (D) Lactose persistence (14) Which of the following statements best describes the type of evolution described in the video? (A) Biological and cultural evolution have acted in opposition. (B) Different molecular adaptations have resulted in analogous phenotypic adaptations. (C) Different molecular adaptations have resulted in homologous phenotypic adaptations. (D) Identical molecular adaptations have resulted in analogous phenotypic adaptations. (E) Identical molecular adaptations have resulted in homologous phenotypic adaptations.