URGENT: True Breeding Drosophila

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Noor123
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URGENT: True Breeding Drosophila

Post by Noor123 » Thu Mar 13, 2008 8:29 pm

This summarizes the F2 numbers from a cross between two, true-breeding Drosophila P generation, that are different with respect to two traits. The gene alleles can be dominant or recessive and autosomal or X linked.

http://img329.imageshack.us/img329/6837 ... ilajg0.jpg
the thing is, I know that it's X-linked because males outnumber the number of femals , but how do I know whether it's dominant or recessive?? It says provide a hypothesis about the mode of inheritance of the genes by the means of a cross diagram and see whether the data fits the hypothesis with the Chi square test. What's our "expected" number of females/males as well? I AM SO LOST!

I NEED HELP! My tutor is of no help whatsoever. SHe keeps doing mistakes, and I am supposed to get it!! ARGHHHH PLEASE it'd be GREATLY appreciated if you could help me with this. Thank you.

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mith
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Post by mith » Thu Mar 13, 2008 9:00 pm

You should start by tallying up the numbers in a more clear form

for example

curly males
non-curly males(not wildtype!)

curly females
non-curly females

do the same for the eyes trait.

Some patterns should start to emerge. Assuming it is sex linked, find a theoretical distribution of traits for the f2 generation.
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Noor123
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Post by Noor123 » Thu Mar 13, 2008 9:21 pm

Well this is what I have so far

and i Know I am doing this wrong big time because the expected should not be equal between males and females as this is X linked. But I don't know what to doooooo

Image

Cat
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Post by Cat » Fri Mar 14, 2008 2:09 am

I provided an answer for your question on my web. Please, visit http://science-ed.fullsubject.com/1-on- ... t10.htm#11 .

donito
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Re: URGENT: True Breeding Drosophila

Post by donito » Fri Mar 14, 2008 2:22 am

I'm kind of a noob here so someone please correct me if I'm wrong.

First, I'm not real sure I understand your reasoning as to why you think the trait is X-linked. If it's X-linked, then all males will have the trait since they only have one X chromosome and it showing up in females will depend on if the trait is dominant or recessive. I think your results could suggest a autosomal trait especially when you consider there is crossing over only in females. I think a trait showing up in more males could be attributed to crossing over in females producing a heterozygous state, assuming the trait is recessive.

Hope this helps.

Cat
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Post by Cat » Fri Mar 14, 2008 3:19 am

No. F1 generation is heterozygous. Refer to my previous post if you want details.

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