) (14 pts) You have discovered a new species of worms for which the haploid numb
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) (14 pts) You have discovered a new species of worms for which the haploid number is three. You isolated a dumpy worm and want to determine the linkage group of the gene dpy-I. The dpy-I mutation is recessive. Using recessive marker mutations for each chromosome (i.e., marker 1 is on chromosome I, marker 2 is on chromosome II, marker 3 is on chromosome III) you set-up 3 crosses as follows: Cross 1: marker mutation 1 x dpy-1 Cross 2: marker mutation 2 x dpy-1 Cross 3: marker mutation 3 x dpy-1 Fl progeny for the different crosses are allowed to mate, and you select the animals carrying the marker mutation from this cross. You find the following results: Of 300 marker mutation 1 animals, 200 are dpy-1 Of 300 marker mutation 2 animals, 150 are dpy-1 Of 300 marker mutation 3 animals, 15 are dpy-1 a) On which chromosome is dpy-1? You now wish to determine the position of dpy-I on the chromosome. You have identified several other recessive mutations on that chromosome. These other mutations include eyeless and hairy. You have a female worm that is heterozygous for eyeless, hairy, and dpy-1 and testcross the animal (i.e, mate the het to an animal homozygous for eyeless, hairy, dpy-I). Among the 1000 FI progeny from the testcross, the following phenotypes were observed: Dpy-1, eyeless, hairy wild type hairy, dpy-1 eyeless eyeless, hairy dpy-l eyeless, dpy-1 hairy 450 470 30 40 34 36 b) What is the order of genes on the chromosome and the map distances between the genes? 2) (12 pts) You were taking the subway to class one day and captured several family members of an unknown rodent species on the platform. You gave them to your genetics professor to analyze, and she performed the following crosses. The F2 progeny are the result of crossing the FI progeny to each otherExplanation / Answer
Ans B). .The double cross over gametes have lowest frequency and the the important part of the double cross over is that the middle allele moves frtom one sister chromatid to the another. This effectively places the non-parental allele of the middle gene onto a chromosome with the parental alleles of the flanki8ng genes. So, The order of the gene is DPY-1, hairy and eyeless. or it can be eyeless, hairy and DPY-1.
The distance between the DPY-1 and Hairy is = {(30+40+4+6)/1000} X 100 = 8 cM
The distance between hairy and eyeless = {( 34+36+4+6)/1000} X 100 = 8 cM
The distance between each gene 8 cM
A) Question a is not clear.
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