I tried 0.05, 0.025 for RF between a and be 0.09 for RF between c and b but all
ID: 187040 • Letter: I
Question
I tried 0.05, 0.025 for RF between a and be
0.09 for RF between c and b but all were wrong.
You have a Drosophila line that is homozygous for autosomal recessive alleles a, b, and c, linked in that order. You crossed females of this line with males homozygous for the corresponding wild-type alelles. You then cross the F1 heterozygous males with their heterozygous sisters. You obtain the following F2 phenotypes ((where letters denote recessive phenotypes and pluses denote wild-type phenotypes) + + 1364 a b c 365 a b 87 + C 84 a + + 47 + b c 44 + b 4 What is the recombinant frequency between a and b? Decimal answer only. (Note: there is no crossing over in Drosophila males) 0.025 Submit AnswerIncorrect. Tries 3/5 Previous Tries What is the recombinant frequency between b and c? Decimal answer only. 9 Submit Answer Incorrect. Tries 3/5 Previous Tries What is the coefficient of coincidence? Decimal answer only Submit Answer Tries 0/5Explanation / Answer
Answer
Parental genotype. a b c/+ + +
1. If single cross over o myccurs between a and b.
a -----+
+------b
a + progeny = 47+5= 52
+b progeny = 44+4= 48
Recommendation frequency between a and b = 100/2000
= 0.05
b---+
+----c
b+ progeny= 87+4= 91
+c progeny= 84+5= 89
Recommendation frequency between b and c= 180/2000= 0.09
a----+
+-----c
a + progeny = 87+47= 134
+----c progeny = 84+44= 128
Recommendation frequency between a and c= 262/2000= 0.131
Recommendation frequency (%)= distance between the genes
Gene order.
a----5------b-----9----c
Observed double cross over frequency= 9/2000= 0.0045
Expected double cross over= 0.131
Coefficient of coincidence= observed double cross over/expected double cross over
= 0.0045/0.131= 0.034
Interference = 1-coefficient of coincidence
= 1 - 0.034= 0.966