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SCIENCE 10 LIFE SCIENCES: GENETICS Genome British Columbia, 2004 www.genomicseducation.ca MENDELLIAN GENETICS LAB Click on a box to begin. PART A Analyzing results PART C Explaining results PART B PART D Predicting results Experimental design PART A: COMPLETE DOMINANCE INTRODUCTION: You’re back in 1865 and Gregor Mendel is getting ready to publish his results. Being a good scientist, he wants to check that his results are repeatable. You’ve just been hired by Mendel to study the heredity of two traits: 1. seed color: green or yellow 2. seed shape: smooth or wrinkled OBJECTIVE: Mendel gives you three plants that produce the following seeds: yellow, winkled green, smooth yellow, smooth He asks you to breed new plants to determine the genotypes of these plants. PROCEDURE: Click on the plants that you would like to cross. self-fertilize self-fertilize self-fertilize cross-fertilize cross-fertilize cross-fertilize Click here when you have finished collecting all your data. You need to select the plants that you want to cross to see the data. Click anywhere on this screen to go back. You need to select the plants that you want to cross to see the data. Click anywhere on this screen to go back. DATA: self-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. DATA: self-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. DATA: self-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. DATA: cross-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. DATA: cross-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. DATA: cross-fertilized Remember to record this data in your data table. Click anywhere on this screen to go back. Click anywhere on this screen to continue. ANALYSIS: What is the dominant allele for seed color? YELLOW GREEN ANALYSIS: What is the dominant allele for seed color? YELLOW GREEN Yellow ANALYSIS: What is the dominant allele for seed color? YELLOW GREEN Yellow It is the more common color. A dominant allele always covers a recessive allele. ANALYSIS: What is the recessive allele for seed shape? SMOOTH WRINKLED ANALYSIS: What is the recessive allele for seed shape? SMOOTH WRINKLED Wrinkled ANALYSIS: What is the recessive allele for seed shape? SMOOTH WRINKLED Wrinkled It is the less common shape. A recessive allele is always covered by a dominant allele. CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, wrinkled seeds? A. YYSS C. YySs B. YYss D. Yyss CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, wrinkled seeds? A. YYSS C. YySs B. YYss D. Yyss Hint: A self-fertilized parent that produces offspring with the identical traits must be homozygous for both traits. CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, wrinkled seeds? A. YYSS C. YySs B. YYss D. Yyss Hint: A self-fertilized parent that produces offspring with the identical traits must be homozygous for both traits. B. YYss self-fertilized Ys Ys Ys Ys Ys Ys Ys Ys YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the green, smooth seeds? A. YySS C. yySS B. YySs D. yySs CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the green, smooth seeds? A. YySS C. yySS B. YySs D. yySs C. yySS self-fertilized yS yS yS yS yS yS yS yS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, smooth seeds? A. YySs C. YYSs B. YySS D. YYSS CONCLUSION: If we use “Y” for yellow color & “S” for smooth shape. What is the genotype of the plant that produces the yellow, smooth seeds? A. YySs C. YYSs B. YySS D. YYSS A. YySs self-fertilized YS Ys yS YS Ys yS ys ys YYSS YYSs YySS YySs YYSs YYss YySs Yyss YySS YySs yySS yySs YySs Yyss yySs yyss PART B: COMPLETE DOMINANCE (cont.) INTRODUCTION: Before giving Mendel your results from Part A, you decide to verify your results by selffertilizing certain F1 offspring. OBJECTIVES: For the following crosses, predict the genotypes and phenotype ratios for the F2 offspring. PROCEDURE: YYss yySS yySS YySs YySs YYss self-fertilized self-fertilized self-fertilized ? ? ? For each cross, predict the genotype and phenotype ratio, then click on that box to see the expected results. RESULTS: YySs YySs YS Ys yS YS Ys yS ys ys YYSS YYSs YySS YySs YYSs YYss YySs Yyss YySS YySs yySS yySs YySs Yyss yySs yyss Phenotype ratio: RESULTS: YySs YySs YS Ys yS YS Ys yS ys ys YYSS YYSs YySS YySs YYSs YySs Yyss YYss Phenotype ratio: 9 yellow, smooth 3 yellow, wrinkled 3 green, smooth 1 green, wrinkled YySS YySs yySS yySs YySs Yyss yySs yyss RESULTS: yySS yySS yS yS yS yS yS yS yS yS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS If homozygous, then phenotype ratio: RESULTS: yySS yySS yS yS yS yS yS yS yS yS If homozygous, then phenotype ratio: yySS yySS yySS yySS all green, smooth yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS RESULTS: yySS yySS yS yS yS yS yS yS yS yS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS yySS If homozygous, then phenotype ratio: yySS all green, smooth yySS or If heterozygous, then phenotype yySS ratio: yySS RESULTS: yySs yS yS ys ys yySs yS yS ys ys yySS yySS yySs yySs yySS yySS yySs yySs yySs yySs yyss yyss yySs yySs yyss yyss Phenotype ratio: RESULTS: yySs yS yS ys ys yySs yS yS ys ys yySS yySS yySs yySs yySS yySS yySs yySs yySs yySs yyss yyss yySs yySs yyss yyss Phenotype ratio: 12 green, smooth 4 green, wrinkled RESULTS: YYss YYss Ys Ys Ys Ys Ys Ys Ys Ys YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss If homozygous, then phenotype ratio: RESULTS: YYss YYss Ys Ys Ys Ys Ys Ys Ys Ys If homozygous, then phenotype ratio: YYss YYss YYss YYss all yellow, wrinkled YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss RESULTS: YYss YYss Ys Ys Ys Ys Ys Ys Ys Ys YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss If homozygous, then phenotype ratio: YYss all yellow, wrinkled YYss or If heterozygous, then phenotype YYss ratio: YYss RESULTS: Yyss Yyss Ys Ys ys Ys Ys ys ys ys YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss yyss yyss YYss YYss yyss yyss Phenotype ratio: RESULTS: Yyss Yyss Ys Ys ys Ys Ys ys ys ys YYss YYss YYss YYss YYss YYss YYss YYss YYss YYss yyss yyss YYss YYss yyss yyss Phenotype ratio: 12 yellow, wrinkled 4 green, wrinkled PART C: INCOMPLETE DOMINANCE INTRODUCTION: Mendel is impressed with your intelligence and hard work, so he decides to gives you another project to work on. OBJECTIVES: Given the following data, explain the results. DATA: self-fertilized ANALYSIS: Phenotype ratios: F1 F2 ANALYSIS: Phenotype ratios: F1 all medium F2 ANALYSIS: Phenotype ratios: F1 all medium F2 1 long : 2 medium : 1 short ANALYSIS: Phenotype ratios: F1 all medium F2 1 long : 2 medium : 1 short Intermediate phenotype and phenotype ratios indicates incomplete dominance. If we use “L” for long size & “l” for short size. Note: There is insufficient information to determine which allele is more dominant, so long size was arbitrarily chosen as dominant. F1 If we use “L” for long size & “l” for short size. Note: There is insufficient information to determine which allele is more dominant, so long size was arbitrarily chosen as dominant. LL F1 l l ll L L Phenotype ratio: If we use “L” for long size & “l” for short size. Note: There is insufficient information to determine which allele is more dominant, so long size was arbitrarily chosen as dominant. LL F1 l l ll L L Ll Ll Ll Ll Phenotype ratio: If we use “L” for long size & “l” for short size. Note: There is insufficient information to determine which allele is more dominant, so long size was arbitrarily chosen as dominant. LL F1 l l ll L L Phenotype ratio: Ll Ll all medium Ll Ll F2 Phenotype ratio: Ll F2 L l L Ll l Phenotype ratio: Ll F2 L l Ll L l LL Ll Ll ll Phenotype ratio: Ll F2 L l Ll L l Phenotype ratio: LL Ll 1 long Ll ll 2 medium 1 short PART D: CODOMINANCE INTRODUCTION: Mendel’s results were not well received by other scientists. With his extensive experience in growing pea plants, he pursues a career in farming. He decides to selectively breed a new type of corn that produces sweeter, saltier kernels. He starts with one plant that produces sweeter kernels and another plant that produces saltier kernels. He performs several crosses and successfully produces a plant with sweeter, saltier kernels but discovers that his phenotype ratios are not consistent with his pea plant results. After examining his results, you suspect codominance. However, Mendel is not yet familiar with this concept. OBJECTIVE: Assuming that Mendel started with purebreds, design an experiment that illustrates this concept to Mendel. Include a hypothesis. SAMPLE EXPERIMENT PROCEDURE: 1. Cross-fertilize parents with each other 2. Cross-fertilize F1 with each parent to verify parents are purebreds 3. Self-fertilize F1 offspring and compare ratios 4. Repeat EXPECTED RESULTS: Using: A = sweet, a = not sweet B = salty, b = not salty If parent plants are purebreds, then: Positive results for codominance: F1: all sweet, salty (AB) F2: 1 sweet, not salty (AA) 2 sweet, salty (AB) 1 not sweet, salty (BB) Negative results for codominance: i.e. positive results for separate 2 traits F1: all sweet, salty (AaBb) F2: 9 sweet, salty (1 AABB, 2 AABb, 2 AaBB, 4 AaBb) 3 sweet, not salty (1 AAbb, 2 Aabb) 3 not sweet, salty (1 aaBB, 2 aaBb) 1 not sweet, not salty (aabb)