In a threepoint mapping experiment which three general class

In a three-point mapping experiment, which three general classes of offspring are expected (assuming crossovers occur)? How many genotypic classes are expected? In Drosophila Lyra(Ly) and Stubble(Sb) are dominant mutations located at loci 40 and 58, respectively, on chromosome III. A recessive mutation with bright red eyes was discovered and shown also to be on chromosome III. A map is obtained by crossing a female who is heterozygous for all three mutations to a male homozygous for the bright red mutation (which we refer to here as br). The data in the table are generated. Determine the location of the br mutation chromosome III. Calculate the map distances between these three genes. List the order of the genes on the chromosome.

Solution

38. a - the three expected classes are - single crossovers, double crossovers and non crossovers.

b. - There would be 8 different genotypic classes expected 2 for each category - parental, SCO, DCO and NCO