If a single bacteriophage infects one E. coli cell present on a lawn of bacteria and, upon lysis, yields 200 viable viruses, how many phages will exist in a single plaque if three more lytic cycles occur?

Key Concepts

Bacteriophage Life Cycle

Bacteriophages, or phages, are viruses that infect bacteria. Their life cycle can be lytic or lysogenic, with the lytic cycle involving the phage injecting its DNA into the host, replicating, and ultimately causing the host cell to lyse, releasing new phage particles. Understanding this cycle is crucial for predicting the number of phages produced after multiple rounds of infection.

Plaque Formation

A plaque is a clear zone on a bacterial lawn where phages have lysed the bacteria. Each plaque originates from a single phage that infects a bacterial cell, leading to the death of that cell and the release of new phages. The number of phages in a plaque can be calculated based on the number of lytic cycles that occur after the initial infection.

Exponential Growth in Viral Replication

In a lytic cycle, each phage can produce multiple new phages, leading to exponential growth. If one phage produces 200 new phages, subsequent cycles will multiply this number. For example, if three additional lytic cycles occur, the total number of phages can be calculated using the formula for exponential growth, which is essential for determining the final count of phages in a plaque.