Genetics problem involving finding expected phenotypes when given distance in ce

Question

Genetics problem involving finding expected phenotypes when given distance in centimorgans

1) In hamsters, let's assume that the allele for having a tan body (a) is recessive to having an ebony body (A) and having no tail (b) is recessive to having a tail (B). Now, suppose these genes are both located on chromosome II. A true breeding tan-bodied, tailless female was mated to a true breeding wild-type male and that the resulting cross produced F1 phenotvpicallv wild-type females c. Assume the F1 phenotypically wild-type females were mated to F1 tan-bodied, tail-less males and these genes were 15 centiMorgans apart. Of 1000 offspring, what would be the expected phenotypes, and in what numbers would they be expected?

Explanation / Answer

genotypes AA- ebony body , aa- tanbody . bb -no tail and BB- having tail so AaBb - ebony body and having tail

A - tanbody tailless female aabb crossed with wild type male AABB

so this give results - AaBb

by coupling theory they make two parental gamete and two recombinant gamete - AB, AB, Ba, ab

now F1 AaBb crossed with aabb so they give genotype - AaBb     AaBb    aaBb   aabb (similar to test cross also have phenotypic ratio of 1:1:1:1)

now these gene have distance of 15CM and expected phenotype are 4 so 1000/4 = 250 and and these distance have 15 so 15*100 /1000 = 1.5 * 250 = 375 would be linked phenotype which is not recombinant by this distance

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