In guinea pigs, two genes that affect coat color and coat texture are on the sam
ID: 161771 • 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 (bl), 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 blonde, rough
18 brown, rough
17 blonde, smooth
a) Determine the orientation of dominant vs. recessive alleles on the heterozygous parent’s chromosomes. (1pt)
b) Calculate the distance between the coat color and coat texture genes and draw the genetic map. (1pt
Explanation / Answer
a. The arrangement of genes on the chromosome
-------BL-----r-------
-------bl------R------
b. The distance between the coat color and coat texture genes
38 + 29 / 100 x 100 = 65cM