Fly Lab Instructions sample essay

Answer questions on a separate sheet of paper. Be sure to answer all parts of each question. Make sure you number all questions EXACTLY as they are numbered on this worksheet. This assignment will be turned in at the beginning of class before the quiz. Late assignments WILL NOT be accepted. DON’T FORGET: Fly lab/epistasis assignment on pgs. 41-42 in lab manual is also due at the beginning of lab. Assignment 1: Getting to Know FlyLab: Performing Monohybrid, Dihybrid, and Trihybrid Crosses 1.c. Based on what you know about the principles of Mendelian genetics, predict the phenotypic ratio that you would expect to see for the F1 offspring of this cross and describe the phenotype of each fly. 1.d. Are the phenotypes of the F1 offspring what you would have predicted for this cross? Why or why not? 1.g.

What phenotypic ratio do you expect to see in the F2 offspring? 1.h. State your null hypothesis, chi-square value, degrees of freedom and level of significance? Was your ratio rejected or not rejected? 1.j. What did you discover to be the correct phenotypic ratio for this experiment? Was this what you expected? Why or why not? What do the results of this experiment tell you about the dominance or recessiveness of the sepia allele for eye color? 2. What effect, if any, does this have on the results produced and your ability to perform chi-square analysis on these data? If any of your crosses do not follow an expected pattern of inheritance, provide possible reasons to account for your results.

3. Describe the phenotypes that you observed in both the F1 and F2 generations of this cross. How does the observed phenotypic ratio for the F2 generation compare with your predicted phenotypic ratio? Explain your answer. 4. Develop a hypothesis to predict the results of this cross and describe each phenotype that you would expect to see in the F2 generation of this cross. Perform your cross and evaluate your hypothesis by chi-square analysis. State your hypothesis, chi-square value, degrees of freedom, p-value, and whether your hypothesis was rejected or not reject. What was the trihybrid phenotypic ratio produced for the F2 generation? Assignment 2: Testcross

What was the phenotypic ratio for the offspring resulting from this testcross? Based on this phenotypic ratio, determine whether the F1 wild-type female male was double homozygous or double heterozygous for the eye color and body color alleles. Explain your answer. If your answer was double homozygous, describe an expected phenotypic ratio for the offspring produced from a testcross with a double heterozygous fly. If your answer was double heterozygous, describe an expected phenotypic ratio for the offspring produced from a testcross with a homozygous fly. Assignment 3: Lethal Mutations

1. What phenotypic ratio did you observe in the F1 generation? What were the phenotypes? Perform an F1 cross between two flies with the aristapedia phenotype. What phenotypic ratio did you observe in the F2generation? How do these ratios and phenotypes explain that the aristapedia mutation functions as a lethal mutation? What results did you obtain with the cross between a wild-type fly and a fly with the aristapedia mutation? 2. Develop a hypothesis to predict the phenotypic ratio for the F1 generation. Mate these flies. What phenotypic ratio did you observe in the F1 generation? Are the phenotypic ratios that you observed in the F2 generation consistent with what you would expect for a lethal mutation? Why or why not? Explain your answers Assignment 4: Epitasis

1. What did you observe in the F1 generation? Was this what you expected? Why or why not? Which mutation is epistatic? Is the vestigial mutation dominant or recessive? What phenotypic ratio did you observe in the dihybrid F2 generation. Perform a chi-square analysis. State your chi-square value, degrees of freedom, p-value and whether you rejected or failed to reject this ratio. 2. Which mutation is epistatic? Is the apterous wing mutation dominant or recessive?