Question

In Neurospora, an individual with the genotype AB is crossed with one having the genotype ab. The following asci types were observed:

                                        asci types:                                                  # asci fitting pattern:

                                                1          AB aB Ab ab                                    330

                                                2          AB AB ab ab                                  1526

                                                3          aB Ab ab AB                               2

                                                4          AB Ab aB ab                                 167         

Total: 2025

Map the order of the genes, and distance between gene A and the centromere and the distance between gene B and the centromere

Answer 1

Type I	2	3	Type4
AB aB Ab ab	AB AB ab ab	aB Ab ab AB	AB Ab aB ab
330	1526	2	167

Distance from A gene to centromere=( 1/2 SDS)/ total = 1/2x(330+2)/2025= (166/2025)x 100%= 8.2%

Distance between B to centromere {1/2x(167+2)/2025}x100%= 4.2%

Distance between Aand B gene = (TD+1/2NPD)/total= {(330+2)+1/2x0}/2025= 332/2025=0.16x100%= 16%

A------------------centromere-----------B

|<------8.2%-------->|<------4.2%---->|

So total distance will be 8.2+ 4.2= 12.4%

Thanks