Chapter 8- Genetics

Chapter 8- Genetics

Chapter 8- Genetics

BIOS 308 Homework 5 (Ch.3 to Ch5) Name: Due Mon. 09/30/2019 BIOS 308 Homework 5 (Ch. 3 to 5) Write your answer for each question in the space provided. You may wish to work out the problems on a separate sheet of paper then neatly copy your final answers and work for your final answers to this page to be turned in. I am interested to see how you solve each problem. Show all of your work. Leave all proportions as fractions! 1. In the production of purple pigment in sweet peas, the wild-type (+) product of the p+ gene is enzyme P that converts white pigment to purple pigment. This enzyme activity can be measured in tissue extracts and mixtures of tissue extracts. The table below describes the results obtained when enzyme activity is measured in extracts and mixtures of extracts from strains with different p+ genotypes. Complete the table, filling in (a) the phenotype expected in a homozygote; (b) the phenotype expected in a heterozygote (given allele/p+); (c) the phenotype expected in a hemizygote (has the given allele, but no second allele because it has been lost due to deletion); (d) the classification of the allele-loss-of-function or gain-of-function and amorph, hypomorph, hypermorph, neomorph, or antimorph. % of +/+ Genotype activity p*/p* 100 % of +/+ activity when mixed 50:50 with +/+ extract 100 Homozygote phenotype Heterozygote phenotype Hemizygote phenotype Allele classification p/p? 20 60 p²/p² 0 50 p/p3 300 200 p/p” 0 5 p/ps 09 506 Produces red, not purple, pigment. Produces red and purple pigments. 2. In mice, dwarfism is caused by an X-linked recessive allele, and pink coats is caused by an autosomal dominant allele (coats are normally brown). If a dwarf female from a pure line is crossed with a pink male from a pure line, what will be the phenotypic ratios in the Fi and F2 in each sex? Define your gene symbols! 1 Due Mon. 09/30/2019 BIOS 308 Homework 5 (Ch.3 to Ch5) 3. A series of crosses were performed with a recessive mutation in buggers called batwing. In cross 1, two normal-looking buggers were crossed, and all Fi progeny were normal-looking. In cross 2, two other normal-looking buggers were crossed, but this time, all the Fi progeny were batwing. When either set of F1 were intercrossed, half the crosses resulted in all batwing F2 while the other half of the crosses resulted in all normal F2. What is the genetic basis of this inheritance pattern? 4. A dominant allele H reduces the number of body bristles that Drosophila have, giving rise to a “hairless” phenotype. In the homozygous condition, H is lethal. An independently assorting dominant allele S has no effect on bristle number except in the presence of H, in which case a single dose of S suppresses the hairless phenotype, thus restoring the hairy phenotype. However, S also is lethal in the homozygous (SS) condition. a. What ratio of hairy to hairless flies would you find in the live progeny of a cross between two hairy flies both carrying Hin the suppressed condition? b. When the hairless progeny are backcrossed with a parental hairy fly, what phenotypic ratio would you expect to find among their live progeny? 2 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 The pedigree below is for blue sclera (bluish thin outer wall of the eye) and brittle bones. a. Are these two abnormalities caused by the same gene or by separate genes? State your reasons clearly. b. Is the gene (or genes) autosomal or sex-linked? Why? Does the pedigree show any evidence of incomplete penetrance or expressivity? If so, make the best calculations that you an of these measures. C. CO3 12 OD 50 bo 0 0.00 3 4 5 6 7 8 9 10 11 12 13 14 15 12 LE ood 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 11 12 13 IV U O 1 2 3 4 5 6 7 8 9 10 I= blue sclera brittle bones 3 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 The pedigree below is for blue sclera (bluish thin outer wall of the eye) and brittle bones. a. Are these two abnormalities caused by the same gene or by separate genes? State your reasons clearly. b. Is the gene (or genes) autosomal or sex-linked? Why? Does the pedigree show any evidence of incomplete penetrance or expressivity? If so, make the best calculations that you an of these measures. C. CO3 12 OD 50 bo 0 0.00 3 4 5 6 7 8 9 10 11 12 13 14 15 12 LE ood 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 11 12 13 IV U O 1 2 3 4 5 6 7 8 9 10 I= blue sclera brittle bones 3 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 The pedigree below is for blue sclera (bluish thin outer wall of the eye) and brittle bones. a. Are these two abnormalities caused by the same gene or by separate genes? State your reasons clearly. b. Is the gene (or genes) autosomal or sex-linked? Why? Does the pedigree show any evidence of incomplete penetrance or expressivity? If so, make the best calculations that you an of these measures. C. CO3 12 OD 50 bo 0 0.00 3 4 5 6 7 8 9 10 11 12 13 14 15 12 LE ood 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 11 12 13 IV U O 1 2 3 4 5 6 7 8 9 10 I= blue sclera brittle bones 3 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 The pedigree below is for blue sclera (bluish thin outer wall of the eye) and brittle bones. a. Are these two abnormalities caused by the same gene or by separate genes? State your reasons clearly. b. Is the gene (or genes) autosomal or sex-linked? Why? Does the pedigree show any evidence of incomplete penetrance or expressivity? If so, make the best calculations that you an of these measures. C. CO3 12 OD 50 bo 0 0.00 3 4 5 6 7 8 9 10 11 12 13 14 15 12 LE ood 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 11 12 13 IV U O 1 2 3 4 5 6 7 8 9 10 I= blue sclera brittle bones 3 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 The pedigree below is for blue sclera (bluish thin outer wall of the eye) and brittle bones. a. Are these two abnormalities caused by the same gene or by separate genes? State your reasons clearly. b. Is the gene (or genes) autosomal or sex-linked? Why? Does the pedigree show any evidence of incomplete penetrance or expressivity? If so, make the best calculations that you an of these measures. C. CO3 12 OD 50 bo 0 0.00 3 4 5 6 7 8 9 10 11 12 13 14 15 12 LE ood 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 11 12 13 IV U O 1 2 3 4 5 6 7 8 9 10 I= blue sclera brittle bones 3 BIOS 308 Homework 5 (Ch.3 to Ch5) Due Mon. 09/30/2019 6. In a certain species of fly, the normal eye color is red (R). Four abnormal phenotypes for eye color are found: two are yellow (Y1 and Y2), one is brown (B) and one is orange (O). A pure line is established for each phenotype, and all possible combinations of the pure lines were crossed. Flies of each F1 were intercrossed to produce the F2. The F1 and F2 flies are shown within the square below. The pure lines are listed at the top and the left of the square. a. Determine the number of genes involved. Define your own symbols and list the genotypes of all four pure lines. b. Show how the Fi phenotypes and the F2 ratios are produced. c. Show a biochemical pathway that explains the genetic results, indicating which gene controls each enzyme. Y1 B 0 F F: all R 9R 11 all F F2 all Y all Y WIR all R 9R 9R 4 Y 40 3B 3 Y all R 9R 9R 4 Y 4 Y 3B 30 all B all R all B 9R Y2 F1 F 3B F F. allo

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