map distance between two gene loci

j.wallis j.wallis at
Sun Apr 29 07:17:46 EST 2001

I really hope someone can help we with a lab report I'm having trouble

I have to work out the map distance between two genes, buff and yellow,
using the data below:

      Spore colour arrangement                             Class total
· 4(buff): 4(yellow)                                              2526
· 2(buff): 2(yellow): 2(buff): 2(yellow)                  1150
· 2(buff): 4(yellow): 2(buff) or vice versa              368
· Asci containing only buff and yellow but
Unequal numbers of each (e.g. 5 buff and
3 yellow)
· 2(buff): 2(white): 2(black): 2(yellow)                   1508
· 2(buff): 3(white): 1(black): 2(yellow) or               220
2(buff): 3(black): 1(white): 2(yellow)
· 4(black): 4(white)                                                425

by+ = buff spores
b+y = yellow spores
b+y+ = dark spores (wildtype)
by = white spores

We have been given the following formula:

Map distance (mu) = total number of recombinant gametes X 100
                                   Total number of all gametes

Anyone any ideas how I should go about working this one out? Any help
greatly appreciated. Pease send any emails to plyujlw at



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