Name_____________________________Date___________________Period_____________ Seedlings for Genetics Objective: In this lab, you will germinate and grow F2 corn seeds to determine inheritance patterns by following monohybrid traits and dihybrid traits. You also will compare your results to Mendel’s Results Materials: Genetic Corn Seed, cups, paper towels or soil Monohybrid: Studying one-factor segregation, we will follow one trait characteristic (coloration) with 2 allele results (green or albino) corn. The albino characteristic is a lethal chlorophyll mutant, so that homozygous green and heterozygous green are normal in color. The albino strain is recessive and has almost no pigment. A-green pigment a-albino pigment P generation: If a homozygous green and a homozygous albino corn were bred, what would the F1 generation results show? A a a A Genotype: Phenotype: Cross the F1 generation to get the F2 Genotype: Phenotype: Name_____________________________Date___________________Period_____________ Write a hypothesis: If the class grows F2 generation corn, and follows just the characteristic of color, then__________________________________because_________________________________________ _____________________________________________________________________________________ Chi Square Analysis: If a person were to flip a coin 100 times, how many heads and how many tails should they get?...50 heads and 50 tails. Suppose that he got 51 heads and 49 tails….did he just disprove probability? What about 55:45? What about 60:40? At what point does one conclude that the coin is likely abnormal or that some other aspect of the experiment is likely askew? Chi Square to the rescue! Chi square determines whether or not results seem to confirm or call into question a hypothesis. Null Hypothesis vs. Alternative Hypothesis Null: no statistically significant difference between expected and observed results Alternative: explanation (hypothesis) of why the results are so different from what’s expected Monohybrid Data and Calculations: Color of Corn Observed Number Expected Number Green .75 x Total Albino .25 x Total Total: Total: Difference between observed and expected Difference Squared Squared Difference/ expected number 0 n/a X2 = Name_____________________________Date___________________Period_____________ We will use this chart: 1 degree freedom Hypothesis is Supported Hypothesis not supported Differences are Insignificant Differences are significant p C-1 1 2 0.99 0.95 0.80 0.50 0.30 0.20 0.10 0.05 .00016 .0201 .0039 .103 .064 .446 .455 1.386 1.074 2.408 1.642 3.219 2.706 4.605 3.841 5.991 Dihybrid Now we will look at two-factor cross by following the characteristic of color and height. We know green is dominant to the albino allele, but we will also follow the alleles of height. The tall allele is dominant over the recessive dwarf allele. D-tall height d-dwarf height A-green pigment a-albino pigment P generations: a pure bred homozygous green tall plant was pollinated with a purebred homozygous albino dwarf plant ___ ___ ___ ___ X___ ___ ___ ___ Genotype: Phenotype: Name_____________________________Date___________________Period_____________ F1: Breed offspring of P generation ___ ___ ___ ___ X___ ___ ___ ___ Genotype: Phenotype: Write a hypothesis: If the class grows F2 generation corn, and follows the characteristics of color and height, then ________________________________________________________________________ because___________________________________________________________________________ Dihybrid Data and Calculations Color and Height Observed Number Expected Number Green Tall Total x9/16 Green Dwarf Total x 3/16 Albino Tall Total x 3/16 Albino Dwarf Total x 1/16 Total: Total: Difference between observed and expected Difference Squared Squared Difference/ expected number 0 n/a X2 = Name_____________________________Date___________________Period_____________ We will use this chart: 3 degree freedom Hypothesis is Supported Hypothesis not supported Differences are Insignificant Differences are significant p C-1 1 2 3 0.99 0.95 0.80 0.50 0.30 0.20 0.10 0.05 .00016 .0201 .115 .0039 .103 .352 .064 .446 1.005 .455 1.386 2.366 1.074 2.408 3.665 1.642 3.219 4.642 2.706 4.605 6.251 3.841 5.991 7.815 Results: 1. Was your hypothesis in the monohybrid cross supported or rejected? Explain. 2. Was your hypothesis in the dihybrid cross supported or rejected? Explain. 3. Name 3 sources of error? Effects they had data. Conclusion: What did you learn from this lab?