Genetics

[Belgarion]

This efly assignment is driving me a bit nuts so any help would be appreciated:

i have 2 different mutations in drosophila : yellow body and singed bristle

i need to perform no more than 3 crosses and answer these questions:

Are the loci autosomal or X linked or one of each? 
Is there lethality?
What is the dominant phenotype at each locus?
Are the loci assorting independently or are they linked?
If linked what is the map distance between them? If not is there gene interaction?

i can do 1000 crosses using a program, someone please help.

Thanks

[Leronziia]

Think of the different crosses we have learnt: test crosses, back crosses, reciprocal crosses.
Your knowledge of how X-linked traits pass from mother to male offspring is also worthwhile.

My combination of mutations were X-linked and the best way I found was to have an affected mother cross with male wild type. Then showing that all the male offspring exhibit the mutations that the mother had is sufficient to conclude it was X-linked.

Start from here and see how you go.

[hobbitle]

...wasn't this assignment due like 2 weeks ago?

[Shenz0r]

...wasn't this assignment due like 2 weeks ago?

This assignment is for Biomedicine students lol

[Belgarion]

Think of the different crosses we have learnt: test crosses, back crosses, reciprocal crosses.
Your knowledge of how X-linked traits pass from mother to male offspring is also worthwhile.

My combination of mutations were X-linked and the best way I found was to have an affected mother cross with male wild type. Then showing that all the male offspring exhibit the mutations that the mother had is sufficient to conclude it was X-linked.

Start from here and see how you go.

Thanks for the tip. I had no problem working out that mine was x - linked also, its the lethality and last point im having problems with.

[Leronziia]

I'm not too sure about how to deal with the lethal part also; I crossed a heterozygote female with a wild type male and concluded that since all the affected males survived (or actually showed up as progeny), then the traits weren't lethal.

As for mapping the loci distance, cross a heterozygote female with an affected male and look at your data. You should be able to see the recombinants and calculate the map distance.

[Shenz0r]

I'm not too sure about how to deal with the lethal part also; I crossed a heterozygote female with a wild type male and concluded that since all the affected males survived (or actually showed up as progeny), then the traits weren't lethal.

For mine, I just looked at my cross with a heterozygote female and an affected male. There were males and females for all of the possible phenotypic classes (wild type, tan body + white eyes, white eyes, tan body) hence I concluded that my traits weren't lethal.

And awks has anybody else determined all five conclusions based on only two crosses...

[vox nihili]

This efly assignment is driving me a bit nuts so any help would be appreciated:

i have 2 different mutations in drosophila : yellow body and singed bristle

i need to perform no more than 3 crosses and answer these questions:

Are the loci autosomal or X linked or one of each? 
Is there lethality?
What is the dominant phenotype at each locus?
Are the loci assorting independently or are they linked?
If linked what is the map distance between them? If not is there gene interaction?

i can do 1000 crosses using a program, someone please help.

Thanks

To confirm, you should be able to google those traits as well.

[M-D]

i am really stuck with section 1 of this assignment. my mutations are vestigial wings and brown eyes. I don't know where to start.

I have tried with eFly making the female vestigial and brown and the male also vestigial and brown (is this correct?). but what do i with the number of the offspring i get?

Any help will be greatly appreciated.

Thanks

[Belgarion]

Hey M-D,

I have the exact same mutations for part one. You basically do a 2 point test cross. First cross a pure breeding wild type female crossed with a pure breeding male that has both mutations. The second cross is then a wild type female from the offspring (F1 generation), which is a heterozygote but the program doesnt actually tell you this, with a pure breeding male with the 2 mutations.

[M-D]

Thanks for that 2smart4u. I appreciate it.