Bacteriophage

Definition

A bacteriophage is a virus that infects and replicates within bacteria. They are composed of proteins that encapsulate a DNA or RNA genome.

5 Must Know Facts For Your Next Test

1. Bacteriophages have two main life cycles: the lytic cycle and the lysogenic cycle.
2. In the lytic cycle, bacteriophages replicate within a host bacterium, eventually causing its lysis (destruction).
3. During the lysogenic cycle, the phage genome integrates into the bacterial chromosome and replicates along with it without killing the host.
4. Bacteriophages are highly specific to their bacterial hosts due to receptor recognition on bacterial cell surfaces.
5. They play a significant role in horizontal gene transfer among bacteria through mechanisms like transduction.

Review Questions

• What are the two main life cycles of bacteriophages?
• How do bacteriophages contribute to horizontal gene transfer in bacteria?
• Why are bacteriophages specific to their bacterial hosts?

Related terms

Virus:

A microscopic infectious agent that replicates only inside living cells of an organism.

Lytic Cycle:

A viral reproductive cycle resulting in the destruction of the infected cell and its membrane.

Transduction:

The process by which DNA is transferred from one bacterium to another by a virus.