Molecular Biology of the Gene 7th Edition by Richard Losick, James Watson, Michael Levine, Tamara Baker, Alexander Gann

Exercise 7

You are mapping the 6th chromosome of the sheep blowfly Lucilia cuprina and want to test how your calculations compare to a published map. In a recent cross, you studied the mutations tri , pk , and y that display thickened vein junctions, pink body color, and yellow eyes, respectively. From a cross between a male homozygous for the three mutations and a heterozygous female ( tri pk y/+++ ), you record the counts for the progeny. In the published map, the distance between y and pk is 23.0 m.u., the distance between pk and tri is 18.4 m.u., and the distance between y and tri is 41.4 m.u. Based on the published map and given values below, calculate the expected values for observed progeny that represent either a single or double crossover. Remember that your observed values are data that include some statistical fluctuations.
Total progeny counted: 1000
Total recombinants that represent a double crossover: 15
Published map information from Weller and Foster (1993. Genome 36: 495-506).