1) Let’s say you infect E. coli with a double mutant phage then spread the E. cl

Question

1) Let’s say you infect E. coli with a double mutant phage then spread the E. cloi on an agar plate. The phage contains the RII mutation (FC0) and a revertant of FC0. Describe the plaque morphology (or morphologies) you expect to see on the agar dish? If you expect to see more than one morphology, explain which morphologies are expected to be rare and which are expected to be common. Explain your reasoning.

Answer:

You would see two types of morphologies. One belonging to the revertant and the other to the mutant.

Since the genome contains both the genes, both will be expressed. The revertant however would be more in number than the mutant. This is because the proteins from the revertant may act as a repressor for the mutant gene.

2)Now let’s say you co-infect E. coli with the double mutant strain described aboveand WT phage (1:1 ratio). Now describe the plaque morphology (or morphologies) you expect to see on the agar dish? If you expect to see more than one morphology, explain which morphologies are expected to be rare and which are expected to be common. Explain your reasoning.

Please help me with question 2 Thank you

Explanation / Answer

Here, we can see WT phage induced plaques so often and double mutant plaques as rare. Since, there would be a competation between both the phages to infect E.coli, WT phage as a natural infectant of E. coli can dominate produce large number of clear zones on the agar plate, unlike, double mutant phage which may not form completely clear plaques.

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