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Welcome Back from Break

Welcome Back from Break. This may have been your life on break. This may be your life on Tuesday. This is what we are returning to in L319. Great Job – Keep up the good work!!!. Remember wit trait found in the A strain . Genotype: 50% wit/+; 50% wit/y Phenotype: females: 100% WT (red)

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Welcome Back from Break

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  1. Welcome Back from Break This may have been your life on break

  2. This may be your life on Tuesday

  3. This is what we are returning to in L319

  4. Great Job – Keep up the good work!!!

  5. Remember wit trait found in the A strain Genotype: 50% wit/+; 50% wit/y Phenotype: females: 100% WT (red) males: 100% white eyes Genotype: 25% wit/wit 25% wit/+ 25% wit/Y 25% +/Y Phenotype: 50% white eyes 50% WT (red)

  6. Other Direction: Genotype: 50% wit/+; 50% +/y Phenotype: females: 100% WT (red) males: 100% WT (red) Genotype: 25% wit/+ 25% +/+ 25% wit/Y 25% +/Y Phenotype: Males: 50% WT; 50% white Females: 100% WT (red)

  7. What about hsy? Genotype: 100% hsy/+ Phenotype: 100% WT (red eyes) Genotype: 25% hsy/hsy 50% hsy/+ 25% +/+ Phenotype: 25% hershey eyes 75% WT (red eyes)

  8. What % of the flies in the F2 generation should have hershey eyes if wit is epistatic to hsy? From the following crosses: Po: A female X hsy male F2 males: 50% white eyes, 50% WT (red) F2 females: 50% white eyes, 50% WT (red) Po: hsy female x A male F2 males: 50% white eyes, 50% WT (red) Frequency white eyes = 0.5 Frequency hershey eyes = 0.25 % of flies with hershey eyes = 0.50 x 0.25 = 0.125 or 12.5% From the F2 females from Po: hsy female x A male No white eyed flies, no epistasis = 25% of flies should have hershey eyes

  9. Thus a white eye fly could be: 1. hsy/hsy 2. hsy/+ 3. +/+ How can we find out the hsy genotype of a white eye male fly? Can set up another cross: F2 white-eyed male x hsy female Will you see any white eyed flies in the offspring? No

  10. What are the possible phenotypes if the F2 male genotype is: Genotype: 100% +/hsy Phenotype: 100% WT (red) Genotype: 50% hsy/hsy, 50% +/hsy Phenotype: 50% hershey eyes, 50% WT (red) Genotype: 100% hsy Phenotype: 100% hershey eyes Unfortunately we don’t have any live F2 male flies to set up these crosses.

  11. Will look at the genotype of frozen F2 white-eyed males using a different technique to differentiate the Hsy+ and hsy alleles: Polymerase Chain Reaction (PCR)

  12. Genotype: 25% - 1425/ 1425 50% - 750/ 1425 25% - 750/ 750

  13. Remember the sht trait found in A strain This trait is found on Chromosome 2 The scores of F2 Data from both reciprocal crossed showed that: 48 out of 2870 flies were scored to have both hershey eyes and short wings? Is this possible?

  14. Remember: Male flies do not undergo recombination Do you see hershey, short flies? No How can you explain the data?

  15. Experiment 4: Tetrad Analysis Let’s go over one Gene Pair Calculation

  16. 1. Do PD = NPD? PD = 67 NPD = 73 Total = 140 Χ2 = (67-70)2 + (73-70)2 = 0.26 < 3.84 - Can not reject Null Hypothesis 70 70

  17. 2. Do PD:NPD:4TT? PD = 67 NPD = 73 TT= 48 Total = 188/6 = 31.3 Χ2 = (67-31.3)2 + (73-31.3)2 + (48-125.3)2 = 143.9 > 5.99 – Reject Null Hypothesis 31.3 31.3 125.3

  18. Calculate Centromere Distance • Total Centromere Distance = 48 x 100 = 12.7 • 2(188) • Given = Ura is 8 cM from its centromere • Distance of Leu from its centromere = 12.8 cM – 8 cM = 4.7

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