Exam 2 answers
Exam 2 answers BIOL 2140
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This 11 page Study Guide was uploaded by Abby Notetaker on Monday August 8, 2016. The Study Guide belongs to BIOL 2140 at University of Nebraska at Omaha taught by Dr. Jill Blankenship in Fall 2016. Since its upload, it has received 11 views. For similar materials see Genetics in Biology at University of Nebraska at Omaha.
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Date Created: 08/08/16
BIOL2140 Exam 2 Spring 2016 name:________________________________ BIOL2140 Genetics Spring 2016 Exam 2 18% of your final grade 1. Put your name on each page of the exam in case pages get separated. 2. Answer to the best of your ability. 3. Write legibly!!! 4. Unless otherwise stated, calculate using 2 decimal places. 5. You do not need to turn in this front page. 6. Cheating is not tolerated. Cheating, action(s) reasonably perceived as cheating, or attempted cheating will negatively affect your final course grade, and may be referred to the appropriate dean or committee for further investigation, which may be recorded in your academic file. 1 BIOL2140 Exam 2 Spring 2016 name:________________________________ Equations: 2 2 pW 2pqW qW 11 12 22 H =V /G , P h =V /A ,P V PV +G +V E GE V GV +A+V ,IR=hDS 2 2 BIOL2140 Exam 2 Spring 2016 name:________________________________ 1. Stripe (ST) encodes a striping pattern in fish and is dominant to no stripes (st). This gene is a maternal effect gene. An st/st female is mated to an ST/ST male. (1.5 pts each) a. What is the genotype and phenotype of their F1 offspring? ST/st All no stripe b. A female from the F1 generation is mated to an st/st male. What is the genotype and phenotype of their offspring? ST/st and st/st, all striped. Learning goal: Predict the outcomes of of maternal affect and imprinting crosses. 2. In a species of birds, a white chest patch is more prevalent in males than females (a sex-influenced trait). The WC allele, encoding a white chest patch is dominant in males, while it acts as a recessive allele in females (the other allele, WC , encodes bland chest color). A WC WC 1 2 female mates with a WC WC . What ratio of no white chest:bland chest do you expect to see in male offspring? Female offspring? (4 pts) ¾ white chest male:1/4 bland chest male, ¼ white chest female, ¾ bland chest female. Learning goal: Predict the outcomes of of maternal affect and imprinting crosses. 3. The following pedigree describes a disease within a family. Use this to answer the following questions. I 1 2 II 1 2 3 4 5 6 7 III 1 2 3 5 6 7 8 9 10 11 12 4 IV 1 2 4 5 6 7 8 9 10 11 12 13 3 V 2 3 4 1 a. What is the most likely inheritance pattern for the characteristic in the pedigree above? (3 pts) autosomal recessive 3 BIOL2140 Exam 2 Spring 2016 name:________________________________ Learning goal: Identify the nature of genetic trait based on the pattern of inheritance shown in a pedigree. b. What is the probability that IV-2 and IV-3 are both carriers of the disease ? (1.5 pts) 1/2 Learning goal: Predict progeny outcomes/probabilities based on pedigree information. c. What is the probability that the first child of IV-2 and IV-3 will be affected? (1.5 pts) 1/8 Learning goal: Predict progeny outcomes/probabilities based on pedigree information. 4. In the pedigree below, the rare trait is autosomal recessive. If the frequency of heterozygotes for the trait in the general population is 1/15, then what is the probability of II-2 having an affected child with his phenotypically normal wife (she is not shown)? (3 pts) I 1 2 II 1 2 1/90 Learning goal: Predict progeny outcomes/probabilities based on pedigree information. 5. An individual has the following genotype. Gene loci (A) and (B) are 34 cM apart. Indicate all the possible gametes that this individual can produce, and the proportions of expected progeny genotypes if a testcross is performed on this individual. (8 pts) A b a B Gametes Percentage of progeny Ab 33 aB 33 AB 17 ab 17 Learning goal: Predict progeny outcomes given information about genetic linkage 4 BIOL2140 Exam 2 Spring 2016 name:________________________________ 6. You work in an agricultural biotech company and have two pure- breeding strains of apples. One tree produces smooth fruit with low sugar content levels. The other tree produces wrinkled fruit with high sugar levels. Crossing these strains yields F1 progeny with wrinkled fruit and low sugar levels. Crossing F1 progeny with a pure-breeding strain with smooth fruit and high sugar levels yields the following progeny: wrinkled fruit, high sugar levels 240 smooth fruit, low sugar levels 238 wrinkled fruit, low sugar levels 155 smooth fruit, high sugar levels 167 total 800 a. Which fruit surface and sugar level alleles are dominant? (1 pts) wrinkled, low sugar b. If fruit surface and sugar level are linked, how far apart are they based on this data? (3 pts) Learning goal: Calculate genetic distance based on progeny outcomes in two and three-point crosses. c. Using the chi-square test for independent assortment, calculate the expected values for these phenotypes in the underlined cross (round to nearest whole number)? (8 pts) Phenotype Expected progeny wrinkled fruit, high sugar 201 smooth fruit, low sugar 199 wrinkled fruit, low sugar 194 smooth fruit, high sugar 206 The blank chart below might be useful… d. What is the chi-square value for this data? (4 pts) 30.43 5 BIOL2140 Exam 2 Spring 2016 name:________________________________ e. How many degrees of freedom are there in this chi-square analysis? (1 pts) 1 f. What is the P-value range and does this support linked genes? (2 pts) P<<0.001, which refutes the null hypothesis of independent assortment, therefore supporting linkage. Use the chi-square test of independence to confirm or refute linkage between genes 7. In a particular plant, fuzzy stalk (f) is recessive to smooth stalk (F), white flower (r) is recessive to red flower (R), and bristle-less seed (b) is recessive to bristled seed (B). All three recessive mutations are autosomal. A plant heterozygous for all three characteristics is crossed with a fuzzy stalk, white flower, bristle-less seed plant and the following progeny are observed (only gametes from the heterozygote shown for clarity): f R b 425 F r B 404 f r b 202 F R B 189 f r B 126 F R b 115 f R B 22 F r b 17 Total 1500 a. Determine the parental genotype (which alleles are on the same chromosome) of the F1 parent in this cross and write it below. (3 pts) fRb/FrB Learning goal: Identify parental genotypes based on progeny outcomes. b. Determine the order of these genes on the chromosome and draw them on a map below. (3 pts) F—18.7—B—28.7—R Learning goal: Calculate genetic distance based on progeny outcomes in two and three-point crosses. c. Calculate the map distances between the genes and put them on the map in (b). Keep one significant digit after the decimal point. (4 pts) 6 BIOL2140 Exam 2 Spring 2016 name:________________________________ d. Determine the coefficient of coincidence and the interference among these genes. (2 pts) coc=0.48, I=0.52 Learning goal: Calculate genetic distance based on progeny outcomes in two and three-point crosses. 8. The average seed number from parents and offspring of a particular plant are shown below. Parents Offspring 45 60 32 45 16 35 55 58 a. What is the correlation coefficient for this data? (3 points) 0.95 b. If a set of parents had an average of 40 seeds, what is the expected average number of seeds in their offspring? (3 points) 51.5 Learning goal: Measure the correlation coefficient between two characteristics and extensions of learning goals from chapter 24. 9. A sheep shearer has determined the following variances for raw wool weight in his flock: Total phenotypic variance 28 Additive genetic variance 15 Dominance genetic 4 variance Environmental variance 7 Assume that there is no genetic-environmental interaction. a. Calculate the total genetic variance. (2 pts) 21 b. Calculate the broad-sense heritability indicated by this data. (2 pts) 0.75 c. Calculate the narrow-sense heritability indicated by this data. (2 pts) 0.54 d. The breeder wishes to improve yield. If the average wool yield in the starting population is 20 lbs and he selects for breeding sheep with an average yield of 28 lbs, what will be the expected average yield 7 BIOL2140 Exam 2 Spring 2016 name:________________________________ among the offspring of the selected plants? (two significant digits after the decimal) (3 pts) 24.29 Learning goals: -Calculate H and/or h using a variety of methods (based on available data). –and- -Estimate effects of selection on subsequent generations 10. Suppose that in a population the frequency of individuals with a particular recessive condition is 1/95. Assume the presence of only a dominant allele (A) and a recessive allele (a) in the population and that the population is at Hardy-Weinberg equilibrium. What is the expected frequency of heterozygotes in the population? (4 pts) 0.18 Learning goal: -Calculate the Hardy Weinberg equilibrium equation given genotype or phenotype ratios for a gene with 2 alleles. 11. Two randomly mating populations of fish exist in two lakes. Both populations have spotted and spotless body fish in their population. Spotless body is encoded by an autosomal d allele that is recessive to the D allele that encodes spots. The frequency of spotless fish in lake 1 is 0.8 and the frequency of spotless fish in lake 2 is 0.1. Both populations have 1000 individuals. One summer, a “helpful” fisherman took 300 fish from lake 1 and introduced them to lake 2. Answer the following questions about these populations. Keep two significant digits after the decimal place. a. What is the f(d) for each population prior to migration? (3 pts) lake 1-0.89, lake 2-0.32 b. What is the f’(d) of lake 2 after migration? (4 pts) 0.45 c. If the population mates randomly following migration, how many heterozygotes are expected to be in the new population in the next generation (if it is also 1000 individuals)? (3 pts) 495 Learning goals: - Predict allele frequencies using H-W predictions. -and- Describe events that alter allele frequencies from H-W equilibrium and calculate their affects on allele frequencies. 12. A population consists of 1080 individuals of the following genotypes: AA Aa aa 224 776 80 8 BIOL2140 Exam 2 Spring 2016 name:________________________________ a. What is the frequency of the A allele? (3 pts) 0.57 b. What is the frequency of the a allele? (3 pts) 0.43 c. What would the expected number of AA, Aa, and aa individuals be if this population was in Hardy-Weinberg equilibrium? (Round to whole numbers) (6 pts) AA-351, Aa-529, aa-200 (numbers varied a little depending on rounding) Learning goals: Calculate the Hardy Weinberg equilibrium equation given genotype or phenotype ratios for a gene with 2 alleles. -Determine whether a population is in H-W equilibrium using chi-square analysis (“c” would be step one in that process). 13. For the Q gene, Qq individuals have a fitness of 1 compared a fitness of 0.2 for QQ and a fitness of 0.6 for qq organisms. What will the frequency of q be when the alleles reach equilibrium? Keep two significant digits after the decimal point.(4 pts) 0.67 Learning goal: -Describe events that alter allele frequencies from H-W equilibrium and calculate their affects on allele frequencies. Bonus A. You are mapping a disease gene that you believe is close to one of the eye color genes in humans. You have generated a LOD score graph mapping from the eye color gene, shown below. Is the disease gene linked? If so, how far is it likely to be from the eye color gene? (3 pts) 9 BIOL2140 Exam 2 Spring 2016 name:________________________________ 0 0.05 0.0.15 0.2 0.25 0.3 0.35 0.45 0.5 Recombination frequency ~22 mu Learning goal: Interpret LOD and GWAS scores B. The locations of four deletions have been mapped to the Drosophila chromosome, as shown in the following deletion map. Recessive mutations a, b, c, and d are known to be located in the same region as the deletions, but the position of the mutations on the chromosome is not known. When flies homozygous for the recessive mutations are crossed with flies heterozygous for the deletions, the following results are obtained, in which “m” represents a mutant phenotype and a plus sign (+) represents the wild type. On the basis of these data, position of the mutant genes on the chromosome (below the chromosome): (4 pts) Mutations Deletion a b c d 1 + + m m 2 + + + m 3 + m m m 10 BIOL2140 Exam 2 Spring 2016 name:________________________________ 4 + + m + 5 m + m + 6 + + + + Learning goal: Intrepret deletion maps and somatic cell- hybridization maps C. The G allele of a particular gene mutates to g at a rate of 3.2 x 10 . g reverts to G at a rate of 7.6 x 10 . What is the frequency of g at equilibrium? 0.30 Learning goal: -Describe events that alter allele frequencies from H-W equilibrium and calculate their affects on allele frequencies. 11
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