© Newbyte Educational Software32Drosophila Genetics Lab © Newbyte Educational Software33Drosophila Genetics LabExp 5 Double Gene Inheritance Name : ___________________________ Date:______________Introduction In this experiment we will examine the inheritance of two genes found on different chromosomes, in Drosophila melanogaster fruit flies. The genes used in this experiment are the black body (2) and curled wing (3) genes. Both wild genes are dominant over the mutant genes. Aim To examine the inheritance of two mutant genes, occurring on separate chromosomes, in three generations of Drosophila melanogaster flies.Procedure1. Click on the Reset then Select buttons and select Saved Parents.2. Select Exp05_f.mfp or Exp05_m.mfp. (f & m are the mutant’s sex)3. Drag each of the parents over to the Observation Platform and record their phenotype and genotype in the first table.4. Click the Breed button and record each offspring’s phenotype.5. During recording, drag a male and female offspring into the Hold Jar.6. Empty the Parent/Offspring area after counting 50 - 100 offspring.7. Drag the held flies into the Parent area and breed them before you examine and record them in table 2. They are still offspring until they are bred and so their genotype may not be visible.8. Record the phenotypes of 300 offspring, then answer the questions.WildFemaleBlack BodyFemaleWildMaleBlack BodyMaleCurled WingFemaleBlack & CurledFemaleCurled WingMaleBlack & CurledMaleResults Record the results observed in the following tables, by placing a stroke in the appropriate column, as each offspring is displayed.Table 1 Parent-Cross ResultsParent DescriptionFemale Phenotype - Genotype -Male “ - “ -Total = Total = Total = Total =Fly ratio Wild : Mutant _______:_______Table 2 Hybrid-Cross (F1 Cross) ResultsHybrid DescriptionFly ratio Wild : Curled : Black : Curled & Black _______:_______:_______:_______Female Phenotype - Genotype -Male “ - “ -WildfliesBlack BodiedfliesTotal = Total = Total = Total =Curled WingfliesCurled Wing & Black BodiedWildfliesBlack BodiedfliesCurled WingfliesCurled Wing & Black Bodied© Newbyte Educational Software34Drosophila Genetics Lab © Newbyte Educational Software35Drosophila Genetics LabDiscussion Questions 1) Complete the following table, which deals with the original parent-cross, between a homozygous wild individual and a homozygous mutant individual. Parent Phenotype Genotype Genotypes of gametes Female Male 2) Complete the Punnett Square below for the homozygote-cross (Parent-cross). phenotype:__________________________ genotype :____________________ GAMETE genotypes phenotype: ______________________________genotype: _______________3) By referring to the Punnett Square above, what would you expect the ratio of wild flies to mutant flies to be? _______ : _______ 4) How well does the ratio of wild : mutant flies observed in the experiment compare to the ratio predicted by the Punnett Square? Why?_________________________________________________________________________________________________________________________________________________________________________________5) Complete the following table, which deals with the hybrid-cross, between two heterozygous individuals. Parent Phenotype Genotype Genotypes of gametes Female Male 6) Complete the Punnett Square below for the hybrid-cross(or F1 cross). phenotype:__________________________ genotype :____________________ GAMETE genotypes phenotype: ______________________________genotype: _______________From the Punnett Square above, what is the expected ratio ofWild : Curled : Black : Curled & Black flies _______:_______ : _______ : _______ 7) How well does the ratio of Wild : Curled : Black : Curled & Black flies observed in the experiment compare to the predicted ratio?___________________________________________________________8) Why would you expect a difference, between the observed and predicted phenotypic ratios?______________________________________________________________________________________________________________________Additional