You cross a mutant with phenotype xyz to a mutant with the p

You cross a mutant with phenotype \'xyz^+\' to a mutant with the phenotype \'x^+ y^+ z\' and test cross the F1. Give this genetic map, predict the phenotypes observed in the offspring, and the number of each expected in a population of 2500 (show your work). x y z

Solution

x/x y/y z⁺/z⁺ X x^+/x⁺ y⁺/y⁺ z/z

gametes x y z+ x+ y+ z

F1 progeny: x/x+ y/y+ z+/z is test crossed with homozygous recessive parent xyz/xyz

eight phenotypes are observed

DCo-double cross over, Sco-single cross over

recombination frequency for SCO b/w x and y is

12= RF/2500*100, RF=300 which includes DCO

RF b/w y and z is

24=rf/2500*100, RF=600 including DCO

calculate DCO frequency.

the probability of x and y is 0.12 and y and z is 0.24, double cross over probability is 0.12*0.24=0.0288

in a progeny of 2500, DCos are 0.0288*2500=72

SCO b/w x and y is 300-72, y and z is 600-72,

parentals are calculated from the rest; 2500-(228+528+72)=1672

x y z+	parental			1672
x+ y+ z	parental
x y+ z	single cross overb/w x and y	228
x+ y z+	single cross overb/w x and y
x+ y+ z+	single cross overb/w y and z	528
xyz	single cross overb/w y and z
x y+ z+	DCO			72
x+ y z	DCO
			total	2500