In the fruit fly Drosophila, a rudimentary wing called \"vestigial\" and dark bo

Question

In the fruit fly Drosophila, a rudimentary wing called "vestigial" and dark body color called "ebony" are inherited at independent loci and are recessive to their dominant wild-type counterparts, full wing and gray body color. Dihybrid wild-type males and females are crossed, and 6400 progeny are produced.

Part A: How many progeny flies are expected to have full wings and gray bodies?

Part B: How many progeny flies are expected to have full wings and ebony bodies?

Part C: How many progeny flies are expected to have vestigial wings and gray bodies?

Part D: How many progeny flies are expected to have vestigial wings and ebony bodies?

Explanation / Answer

I'll show you how to do the genetics, you can do the diagrams. Parental cross ccee x c+c+e+e+ --> F1 all cc+ee+ phenotype wild type i.e. straight wings grey F1 cross cc+ee+ x cc+ee+ All can produce 4 gametes c+e+ c+e ce+ ce, use these to draw a Punnett square. Any genotype with c+ in it will have straight wings, any with e+ will be grey. cc are curly wings and ee ebony wings. The predicted ratio for a dihybrid cross is 9:3:3:1 straight grey: straight ebony: curly grey: curly ebony. Your total progeny number is 343, so you would expect 9/16 *343 = 192.9 for the first class and then 3/16 *343 for the next two classes and 1/16 *343 for the last one. Do these calculations for your expected numbers and then compare with the actual data to see if they fit a 9:3:3:1 ratio using the chi square test. I would have my null hypothesis that the two genes segregate independently.

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