The Neurospora cross was made between a strain that carried mating type A and the mutant allele arg-1(arg) and another strain the carried mating-type a and the wild type arg-1 (+)gene. Four hundred linear octads were isolated and they fell into the 7 categories given in the table below.
a. Label each class and PD, NPD or TT
b. Are the genes linked?
c. What are the map distance between these genes and the centromere?
Class 1 Class 2 Class 3 Class 4 Class 5 Class 6 Class 7
A arg A + A arg A arg A arg A + A +
A arg A + A + a arg a + a arg a arg
a + a arg a arg A + A arg A + A arg
a + a arg a + a + a + a arg a +
127 125 100 36 2 4 6