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Drosophila Crosses with the Bar Mutation

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Drosophila Crosses with the Bar Mutation

Postby Deinonychus » Tue Dec 06, 2005 9:33 pm

I have a couple of questions about some Drosophila crosses. I am in desperate need of help because I cannot figure out why these ratios are the way they are.

Basically, I had to preform reciprocal crosses involving the bar mutation, which is just confusing the hell out of me. I know it's an X-linked mutation, but our results from our crosses look absolutely nothing like a normal X-linked mutation. We also know that it's a semidominant mutation, but this doesn't help with our ratios.

Here's the data:

1) Wild type male X Bar female = 23 bar males and 24 bar females

2) Bar male X wild type female = 45 bar females and 27 wild type males

Basically, I think that our #2 cross is right in terms of trait ratios, but while I'm on the topic, does anyone have ANY idea why we got so many more females? I've been looking for articles on sex ratios or lethal mutations in males but none of them seem to relate to our traits and such. Any ideas?

Our main problem is with the #1 cross. All the data I've seen regarding these traits has completely different ratios, most of which involve having more wild type progeny than bar. We got NO wild type progeny!

Basically, this is driving us insane because if we can't even figure out what's up with our F1 cross, figuring out F2 ratios is just insane. Also doing Chi-Squares on this stuff is going to be seriously screwed up. PLEASE HELP. I will love you forever if you do!
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Postby Deinonychus » Wed Dec 07, 2005 5:57 pm

Never mind, I got it figured out. Thanks for the help though. :P
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