Define plaque, lysogeny, and prophage.

Key Concepts

Plaque

In microbiology, a plaque refers to a clear zone that appears on a bacterial lawn due to the lysis of bacteria by bacteriophages. When a bacteriophage infects a bacterium, it replicates and eventually causes the bacterium to burst, releasing new phages. This results in a visible area devoid of bacteria, which can be counted to determine the concentration of phages in a sample.

Lysogeny

Lysogeny is a viral replication cycle in which a bacteriophage integrates its genetic material into the host bacterium's genome, becoming a prophage. In this state, the viral DNA is replicated along with the host's DNA during cell division, allowing the virus to persist without killing the host. This can lead to a stable relationship between the virus and the host until conditions trigger the lytic cycle.

Prophage

A prophage is the dormant form of a bacteriophage that has integrated its DNA into the host bacterium's chromosome during the lysogenic cycle. In this state, the prophage is replicated along with the host's DNA and can remain inactive for extended periods. Environmental factors or stress can induce the prophage to enter the lytic cycle, leading to the production of new phages and the eventual lysis of the host cell.