Question: 1) Two Strains Of E. Coli, B And K, Can Be Infected By Wild Type (WT) And Rapid Lysis Mutant (RL) T4 Bacteriophages. A) A Lawn Of Bacteria On A Petri Dish Is Infected By A Mixture Of WT And RL Bacteriophages. Assuming A High Bacteria Strain B/bacteriophage Mixture Ratio Is Used For The Experiment, What Is (are) The Size (s) Of Plaques (large Or Small) …

1) Two strains of E. coli, B and K, can be infected by wild type (WT) and rapid lysis mutant (RL) T4 bacteriophages. a) A lawn of bacteria on a petri dish is infected by a mixture of WT and RL bacteriophages. Assuming a high bacteria strain B/bacteriophage mixture ratio is used for the experiment, what is (are) the size (s) of plaques (large or small) produced? In your explanation includes why RL bacteriophages produce large plaques. 6 pts b) A lawn of bacteria on a petri dish is infected by a mixture of WT and RL bacteriophages. Assuming a high bacteria strain K/bacteriophage mixture ratio is used for the experiment, what is (are) the size (s) of plaques (large or small) produced? Briefly explain your answer. 4 pts 2) You use two rapid lysis mutants RL1 and RL2 in a recombination assay with E. coli strain B. Describe the first step of this assay. Include in your description the genotype of the progeny 8 pts 3) At the end of the first step, the total concentration of recovered bacteriophages is 5 x 10 bacteriophages/ml. In the second step, 0.01 mL of the recovered bacteriophages are added to 9.99 mL of SM buffer, and 0.01 mL of this diluted bacteriophage solution is plated on a lawn of E. coli, strain B. We will assume that all the bacteriophages recovered in step 1 are infectious. a) Calculate the total number of plaques (large and small) you expect on the plate of E. coli B. Show your calculation. 5 pts b) If the frequency of recombination between the 2 mutants is 5%, how many plaques would you expect when 1 mL of the diluted bacteriophage solution (see above) is plated on E. coli strain K. Show your calculations. 5 pts 4) Pairwise complementation assays are done between 4 mutants RL1, 2, 3, and 4. Each mutant carry a single mutation a) The following table indicates the number of plaques (large or small) are obtained after plating, on E. coli strain B, the bacteriophages produced during the first step of the complementation assay. RL2 RL3 RL4 RL1 >100 > 100 <10 For each of the 3 complementation assays, how many plaques (few or many) do you expect if the plating had been done, in the same conditions, on a lawn of E. coli strain K? Briefly explain 4 pts b) Based on these 3 complementation assays what is the minimum number of complementation groups for this mutation? Briefly explain. 4 pts c) Do mutants RL2 and RL3 belong to the same complementation group? Explain your answer 4 pts