In guinea pigs, two genes that affect coat color and coat texture are on the sam
ID: 161738 • Letter: I
Question
In guinea pigs, two genes that affect coat color and coat texture are on the same autosomal chromosome. Brown (BL) is dominant to blonde (b/), and smooth (R) is dominant to rough (r). You set up crosses in which one parent is heterozygous and the other is homozygous for the recessive alleles and get the following results: 36 brown, smooth 29 blondes, rough 18 brown, rough 17 blondes, smooth Determine the orientation of dominant vs. recessive alleles on the heterozygous parent's chromosomes. Calculate the distance between the coat color and coat texture genes and draw the genetic map.Explanation / Answer
The cross is: BLbl/ Rr X blbl/rr
Results: (36 + 29) = 65 (Parental)
(17+18) = 35 (Recombinants)
Linkage is there, when parental types > Recombinants.
a)
The orientation of genes is:
Brown--------------------Smooth/Blonde-------------------Rough
b)
The distance between the two genes is: (Number of recombinants/total) *100
=(35/100)*100 = 35map units.