Question

You have created a mutant that is streptomycin resistant (s+), has the ability to photosynthesize (p+), and is resistant to a particular phage, P5 (r+). Your PI would like you to try and move these traits into E. coli by means of generalized transduction.The donor phage has the genotype s+ p+ r+, while the recipient bacterium has the genotype s- p- r-. You carry out selection for the phage resistance trait and then screen all of the r+ transductants for the other two traits. The table below shows the observations from your experiment.

Phenotype Offspring Genotype Phage resistance, photosynthesizing 244 Phage resistance, streptomycin resi stance 37 Phage resistance 96 Phage resistance, streptomycin resistance, and photosynthesizing 123 Total 500 a. Fill in the genotypes on the table above. (0.5 point) b. Calculate the frequency of co-transduction between genes r and s, showing all work (0.5 point) c. Calculate the frequency of co-transduction between genes r and p, showing all work (0.5 point) d. Determine which two genes are closest together and give possible gene orders. (0.5 point) e. Using diagrams to support your answer, determine the correct order of genes on the bacterial chromosome, with respect to what gene is in the middle (0.5 point)

Answer 1

Please look in the image for solution:

Phenotype Genotype Offspring p+r+s- Phage resistance, photosynthesizing 244 Phage resistance, streptomycin resi stance 37 p-r+s+ Phage resistance 96 p-r+s- Phage resistance, streptomycin resistance, and photosynthesizing 123 p+r+s+ Total 500 a. Fill in the genotypes on the table above. (0.5 point)

Cotronscuctien freguency of 3 123 1o0- 402 r and s 540 AA C-tansduction tregueny of 244123 xioo6796 540 r and p AP co- transductionfreguency f s and p 123 100= 227 A 540 As co-transductien frequeny isme higher n r and T en icates that r and p gene Closest to each otierins are. AA e2 compared qene p is closest to as because cotransduction greauency hRj^ more. ps Thats nahy r gene middle than the

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