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 Results 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 Results Parent Description Female Phenotype Male Genotype Vestigial Wing flies Wild Wing flies female male female male 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 Wild Female Vestigial Wing Female Wild Male Vestigial Wing Male Total Total Total Wild flies Total Total Total Vestigial flies Fly ratio Wild Vestigial Table 2 Hybrid Cross F1 Cross Results Hybrid Description Female Phenotype Male Wild Wing flies Aim Genotype Vestigial Wing flies To examine the inheritance of the single mutant allele for vestigial wing in three generations of Drosophila melanogaster flies Procedure 1 2 3 4 5 6 7 8 16 Click on the Reset then Select buttons and select Saved Parents Select Exp01 f mfp or Exp01 m mfp f m are the mutant s sex Drag each of the parents over to the Observation Platform and record their phenotype and genotype in the first table Click the Breed button and record each offspring s phenotype During recording drag a male and female offspring into the Hold Jar Empty the Parent Offspring area after counting 50 100 offspring 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 Record the phenotypes of 200 offspring then answer the questions Drosophila Genetics Lab Newbyte Educational Software Total Wild flies Total Vestigial flies Fly ratio Wild Vestigial Newbyte Educational Software Drosophila Genetics Lab 17 Discussion Questions 1 Complete the following table which deals with the original parentcross between a homozygous wild individual and a homozygous vestigial winged individual Parent Female Male Phenotype Genotype Genotypes of gametes 6 Complete the following table which deals with the hybrid cross between two heterozygous individuals Parent Female Male Phenotype Genotype Genotypes of gametes 7 Complete the Punnett Square below for the hybrid cross or F1 cross phenotype Female 2 Complete the Punnett Square below for the homozygote cross Parent cross phenotype Female GAMETE genotypes Male genotype Male GAMETE genotypes genotype phenotype genotype phenotype genotype From the Punnett Square above what is the expected ratio of NORMAL flies to vestigial winged flies 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 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 Questions 18 Drosophila Genetics Lab Newbyte Educational Software Newbyte Educational Software Drosophila Genetics Lab 19