Homework SourseThe following results were obtained for a testcross progeny
The following results were obtained for a testcross progeny in Drosophila.
w+ m+ f+ 218
w m f 236
w+ m+ f 168
w m f+ 178
w+ m f 95
w m+ f+ 101
w m+ f 3
w+ m f+ 1
a) What is the order of the genes?
b) Construct a genetic map with the mu’s.
Solution
Answer:
Imagine the parental combinations are w+ m+ f+ & w m f 236
1. If single cross over (SCO) occurs between w+ & m+
Normal order= w+---------m+ & w-----m
After cross over= w+-----m & w------m+
w+-----m recombinants are 95+1=96
w------m+ recombinants are 101+3=104
Total recombinants = 200
RF = (200/1000.)*100 =20%
2. If single cross over (SCO) occurs between m+ & f+
Normal order= m+---------f+ & m----f
After cross over= m+-----f & m------f+
m+-----f recombinants are 168+3= 171
m------f+ recombinants are 178+1= 179
Total recombinants = 350
RF = (350/1000)*100 = 35%
3. If single cross over (SCO) occurs between w+ & f+
Normal order= w+---------f+ & w------f
After cross over= w+-----f & w------f+
w+-----f recombinants are 168+95= 263
w------f+ recombinants are 178+101= 289
Total recombinants = 552
RF = (552/1000)*100 = 55.2%
% RF = Map unit distance
The order of genes is -----
w+------20 m.u.------m+---------35 m.u.-----------f+
