Question

When an E. coli cell is infected by multiple phages, what route of infection (lytic or lysogenic) will the phages take? Why? Choose one: O A. either lytic or lysogenic because environmental conditions (such as nutrient levels) play a more important role in determining the type of infection O B. neither lytic nor lysogenic because an E. colicell cannot be infected by more than one phage at a time O C. lytic because the multiple phages in the E. colicell need to move from an area of high concentration inside the cell to infect other cells O D. lysogenic because infection by multiple phages suggests a high concentration of phages in the environment and increased competition for cells to infect

Answer 1

Answer:

The correct option is 'A'

When E.coli is infected by multiple phages,they will take either lytic or lysogenic pathway.

Explanation:

The decision between lysogeny and lytic growth hinges on a delicate balance between the race of two regulatory genes that are C₁ ans Cro viz lambda repressor protein and Cro protein.

If C₁ gene manages to produce enouth repressor which binds or block $O_{R} 1 ,O_{R} 2,O_{L}1 and O_{L} 2$ Operators and turning off all early transcription including transcription Cro genes. That causes Lysogeny.

On the other hand, Cro gene codes for Cro protein which blocks $O_{R3} O_{L} 3$  operators and turning off C₁ genes transcription. This causes Lytic infection.

The winner of the race between C₁ and Cro is determined by the concentration of the $C_{II}$ gene product which is determined by cellular protease concentration. The CII concentration leads to lysogeny.