Please solve this question. Determining gene order using cotransduction frequenc
ID: 36043 • Letter: P
Question
Please solve this question.
Determining gene order using cotransduction frequencies
You decide to use cotransduction to determine the order of the leuB and leuD loci. You use bacteriophage to transduce DNA from an ala3 +leuB +leuD + donor strain into an ala3 leuB leuD recipient strain and select for 10,000 ala3 + transductants. You determine the genotypes of these transductants at the leuB and leuD loci and count the number with each genotype. The following table shows your results:
Please solve this question. Determining gene order using cotransduction frequencies You decide to use cotransduction to determine the order of the leuB and leuD loci. You use bacteriophage to transduce DNA from an ala3 +leuB +leuD + donor strain into an recipient strain and select for 10,000 ala3 + transductants. You determine the genotypes of these transductants at the leuB and leuD loci and count the number with each genotype. The following table shows your results: Using these data, determine the order of IeuA, leuB, and leuD. Place the three loci on the map by dragging the correct label to the appropriate location. (Note: The ma not drawn to scale.)Explanation / Answer
(the information provided does not have anything about leuA)
* Transduction mapping is done as follows:
* select for a gene and test for the other gene. In the example given, ala3+ is selected and the other two genes are tested for their recombinational frequency with reference to the ala3+ gene.
* To check the cotransduction between ala3 and leuB, count the number of recepients positive for both the traits: = 9751 + 1 = 9752/10000 (total number counted) = 0.975
The cotransduction frequency between ala3 and leuB is 0.975
* Cotransduction frequency between ala3 and leuD = 9800/10000 = 0.98
The higher is the recombination frequency, the closer the genes are to each other.
Therefore, the gene order is ala3, leuD, leuB, leuC