Qu Question 1 (15 points) You are tracking three loci in the fruit fly, locis A,
ID: 49941 • Letter: Q
Question
Qu
Question 1 (15 points)
You are tracking three loci in the fruit fly, locis A, B, and C, and want to know whether the loci are linked and if so what their physical distances are from one another as well as the physical order they are in. To find out this information you perform a three-point testcross with a fly that is heterozygous for all three alleles. The progeny of this cross are:
Genotype
Number of individuals
389
410
39
44
77
83
6
5
TOTAL
1053
(a) What is the recombination frequency between loci A and B?
(b) What is the recombination frequency between loci B and C?
(c) What is the recombination frequency between loci A and C?
(d) Are these loci linked?
(e) Demonstrate the physical arrangement of the genes on the chromosome, i.e. the order of the genes on a chromsosome as well as their map distances.
(f) Write out the genotypes of the parents for this cross, indicating which alleles are linked with one another for each parent?
________________________________ X ____________________________________
Genotype
Number of individuals
a/a B/b C/c
389
A/a b/b c/c
410
a/a b/b C/c
39
A/a B/b c/c
44
a/a b/b c/c
77
A/a B/b C/c
83
a/a B/b c/c
6
A/a ;b/b C/c
5
TOTAL
1053
Explanation / Answer
Answers
a) What is the recombination frequency between loci A and B?
Answers: Recombination frequency between Loci A and B are 23.07%
(b) What is the recombination frequency between loci B and C?
Answer: Recombination frequency between Loci B and C are 8.92%
(c) What is the recombination frequency between loci A and C?
Answer: Recombination frequency between Loci A and C are 16.23%
(d) Are these loci linked?
Answer: they are linked.
(e) Demonstrate the physical arrangement of the genes on the chromosome, i.e. the order of the genes on a chromsosome as well as their map distances.
Answer: They are arranged in the order A<-------------->-C,<---------->B.
Answer: Map distance Between A to C is 16.23m.u and between C to B is 8.92m.u and for A to B is 23.07m.u repctively.
(f) Write out the genotypes of the parents for this cross, indicating which alleles are linked with one another for each parent?
Answer: Parents are aBC and Abc . Loci c is the linked with one another for each parent.