posted 03-03-2005 08:00 PM         

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Hello..i am a university student whom is don't a project on genetics, linkage, and Recombination and i am having problem with a few of the many questions that i have to answer...if anyone could help that would be fantastic!
1)Assume there are 12 map units b/w loci in the mouses and that you are able to microscoplcally observe meiotic chromosomes in this organism. If you examine 200 primary oocytes, in how many would you expect to see a chiasma (the physical structure of recombination) b/w the 3 loci mantioned above? what % of gametes should be recombinants
2)If three genes in the order A,B,& C have a probability of a crossover b/w A & B at 25% and B & C at 25%, what is the probability of a double crossover b/w A & C
3)Phenotypically wild-typ F1 female Drosophilia, whose mother had light eyes (lt) abd the father had strawbristles (stw) produced the following when crossed to homozygous light-straw males Phenotype-Light straw # 22, Wild-Type #18, Light # 990, Straw # 970, TOTAL 2000....compute the map distance b/w light and straw
4) In Drosophilia, assume that the gene for scute bristles (s) is located at map position 0.0 and the gene for ruby eyes (r) is at position 15.0 Both genes are located on the X chromosome and are recessive to their wild type alleles. A cross b/w scute-bristled females and ruby-eyed males. Phenotypically wild-type F1 females were then mated to homozygoius double mutant meals and 1000 offspring were produced. Give the phenotypes and frequencies expected

If people know the answers...or even how i could come up with the answers on my own that would be greatly appreciated...I talk everyone in advance for their timely responses!

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