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How to calculate distance between gene on a chromosome

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Assume that the genes for tan body and bare wings are 15 map units apart on chromosome II in Drosophila. Assume also that a tan-bodied, bare-winged female was mated to a wild type male and the resulting F1 phenotypically wild type females were mated to tan-bodied, bare- winged males. Of 1000 offspring, what would be the expected phenotypes and in what numbers would they be expected?

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Solution Summary

Number of recombinants is directly proportional to the distance between genes in map unit. This relationship is utilize in calculating the number of phenotypes.

See Also This Related BrainMass Solution

Determine the linear sequence of these three genes

In Drosophila, a cross was made between females expressing the three X-linked recessive traits: scute (sc) bristles, sable (s) body and vermillion (v) eyes, and wild-type (+) males. In the F1, all females were wild-type, while all males expressed all three recessive traits. The cross was carried to the F2 generation and 1000 offspring were counted with the results shown below.
Offspring #
sc s v 314
+ + + 280
+ s v 150
sc + + 156
sc + v 46
+ s + 30
sc s + 10
+ + v 14

Determine the linear sequence of these three genes.
What is the map distance between these genes?
Is there evidence of interference? If so, calculate it.

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