Exp 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 Wild Black Body Wild Black Body Female Female Male Male Curled Wing Female Black Curled Female Curled Wing Male Black Curled Male 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 Wild flies Curled Wing flies Total Total Black Bodied flies Curled Wing Black Bodied Total Total Fly ratio Wild Mutant Table 2 Hybrid Cross F1 Cross Results Hybrid Description Female Phenotype Male Aim Wild flies To examine the inheritance of two mutant genes occurring on separate chromosomes in three generations of Drosophila melanogaster flies Genotype Curled Wing flies Black Bodied flies Curled Wing Black Bodied Procedure 1 2 3 4 5 6 7 8 32 Click on the Reset then Select buttons and select Saved Parents Select Exp05 f mfp or Exp05 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 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 Record the phenotypes of 300 offspring then answer the questions Drosophila Genetics Lab Newbyte Educational Software Total Total Total Total Fly ratio Wild Curled Black Curled Black Newbyte Educational Software Drosophila Genetics Lab 33 5 Complete the following table which deals with the hybrid cross between two heterozygous individuals Discussion Questions 1 Complete the following table which deals with the original parentcross between a homozygous wild individual and a homozygous mutant individual Parent Female Male Phenotype Genotype Genotypes of gametes Parent Female Male Phenotype Genotype Genotypes of gametes 6 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 Wild Curled Black Curled Black flies 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 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 34 Drosophila Genetics Lab Newbyte Educational Software Additional Questions Newbyte Educational Software Drosophila Genetics Lab 35