Questions 1-4 pertain to the following. A geneticist studying gene linkage in di
ID: 227070 • Letter: Q
Question
Questions 1-4 pertain to the following. A geneticist studying gene linkage in different strains of Drosophila collect two pure-breeding strains in Canada and in Spain. He performs linkage studies of flies within each strain for six traits, associated with loci a through f. He notes the following recombinant frequencies in test crosses, and graphs them into the tables on the right, where recombination frequencies are expressed as percentages:
Canada: Spain:
1. What is the nature of the difference between the two strains?
2. Is a the middle gene between e and b for both strains? What genes flank gene c in both strains?
3. True or false. Theoretically, within each strain, the location of gene b relative to a and c can be mapped by crossing heterozygotes for the a, b and c loci to individuals homozygous recessive for the a, b and c loci.
Questions 1-4 pertain to the following. A geneticist studying gene linkage in different strains of Drosophila collect two pure-breeding strains in Canada and in Spain. He performs linkage studies of flies within each strain for six traits, associated with loci a through f He notes the recombinant frequencies in tesmorosses, and graphs them into the tables on the righ where recombination frequencies are expressed as percentages: Spain: Canada a 0 12 30 3 22 a 0 12 14 23 3 29 0 2 35 15 17 0 37 4 15 37 17 15 0 33 50 d 0 20 50 32Explanation / Answer
1. Based on the recombination frequencies, the order of gene loci on the two chromosomes is different.
In the strain from Canada, the 'f'' loci is farthest from the 'a' loci whereas in the strain from Spain, the 'd' loci is farthest from the 'a' loci.
Order of genes in strain from Canada- a, e,,b, c, d, f
Order of genes in strain from Spain- a, e, c, b, f, d
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