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$8.00 Drosophila genetics
- From Biology: General-Biology , Biology: Reproductive-Biology
- Closed, but you can still post tutorials
- Due on Aug. 29, 2008
- Asked on Aug 26, 2008 at 9:30:22PM
Q:10. A Drosophila geneticist is studying the segregation pattern of the genes held-out wings (ho) and clot eyes (cl) on chromosome 2 and ebony body (e) on chromosome 3 in a particular strain. Surprisingly, she discovers that the three genes are now linked in the strain. In a cross of chromosomally normal ho cl/ho cl; e/e females with ho cl/+ +; e/+ males from the odd strain, she observes that the males are semisterile. The progeny are tabulated below.
ho cl/ho cl; e/e 0
ho cl/+ +; e/e 95
ho cl/ho cl; e/+ 105
ho cl/+ +; e/+ 0
Total 200
a. Why were only two types of progeny recovered in cross A? Explain the absent progeny types.
The geneticist infers that a reciprocal translocation has occurred between chromosomes 2 and 3. To map the translocation breakpoint she carries out the cross of ho cl/+ +; e/+ females (presumed translocation heterozygotes) with ho cl/ho cl; +/+ males having normal chromosomes. The progeny are described below
ho cl/ho cl, semisterile 434
ho cl/ho cl, fertile 2
ho cl /+ +, semisterile 3
ho cl /+ +, fertile 446
ho cl/ho +, semisterile 11
ho cl/ho +, fertile 44
ho cl/+ cl, semisterile 51
ho cl/+ cl, fertile 9
Total 1000
b. What is the estimated map distance (in centimorgans) in females between the locations of ho, cl, and the breakpoint of the translocation? Show your work.
