Genetics

please provide detail explaination for each question

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
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

 

(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 ____________________________________

In a transformation experiment, DNA of a p+q+ strain was used to transform a recipient strain that is auxotrophic for these markers. The number of each class of transformants is shown below:

Class Genotype Number
1 p+q+ 405
2 p+q- 300
3 p-q+ 195

 

  1. a) If the total number of transformants isolated was 900, what is the co-transformation frequency for the p and q loci?
  2. b)Diagram how each class of transformants were obtained starting with the recipient auxotroph. You should include one diagram of the recipient auxtroph, one diagram of the event that led to class 1, one diagram of the event that led to class 2, and one diagram of the event that led to class 3