© Newbyte Educational Software16Drosophila Genetics Lab © Newbyte Educational Software17Drosophila Genetics LabResults Exp 1 Single Gene Inheritance Name : ___________________________ Date:______________Introduction In this experiment we will examine the inheritance of a single gene which governs wing shape in Drosophila melanogaster fruit flies. The gene is found on the second chromosome of our flies and normally results in the fly having a wild flat wing shape. However, a mutant allele has been found which causes the wing to become twisted and useless. This wing shape is called vestigial and the allele causing the change in shape is called the vestigial wing allele.A heterozygous fly possesses an allele for the wild wing shape and an allele for vestigial wing. As wild wing shape is dominant to vestigial, the fly will possess a wild wing phenotype. The symbol used for the wild allele is Vg and the mutant vg. Aim To examine the inheritance of the single mutant allele for vestigial wing, in three generations of Drosophila melanogaster flies.Procedure1. Click on the Reset then Select buttons and select Saved Parents.2. Select Exp01_f.mfp or Exp01_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 jar 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 200 offspring, then answer the questions.WildFemaleVestigial WingFemaleWildMaleVestigial WingMaleRecord 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 “ - “ -Wild Wing fliesVestigial Wing fliesfemale male female maleTotal = Total = Total = Total =Total Wild flies = Total Vestigial flies =Fly ratio Wild : Vestigial _______:_______Table 2 Hybrid-Cross (F1 Cross) ResultsHybrid DescriptionFemale Phenotype - Genotype -Male “ - “ -Wild Wing fliesVestigial Wing fliesTotal Wild flies = Total Vestigial flies =Fly ratio Wild : Vestigial _______:_______© Newbyte Educational Software18Drosophila Genetics Lab © Newbyte Educational Software19Drosophila Genetics LabDiscussion Questions 1) Complete the following table, which deals with the original parent-cross, between a homozygous wild individual and a homozygous vestigial winged 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 vestigial flies to be? _______ : _______ 4) How well does the ratio of wild : vestigial winged flies observed in the experiment compare to the ratio predicted by the Punnett Square? Why?_________________________________________________________________________________________________________________________________________________________________________________5) Why are there usually differences between the number of males and the number of females observed in a random sample of flies?___________________________________________________________6) Complete the following table, which deals with the hybrid-cross, between two heterozygous individuals. Parent Phenotype Genotype Genotypes of gametes Female Male 7) 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 of NORMAL flies to vestigial winged flies? _______ : _______ What are the expected ratios of genotypes? (VgVg : Vgvg : vgvg) _______ : _______ : _______ 8) How well does the ratio of wild : vestigial winged flies observed in the experiment compare to the ratio predicted by the Punnett Square?___________________________________________________________9) Why would you expect a difference, between the observed and predicted phenotypic ratios?______________________________________________________________________________________________________________________Additional