Bacteriophage Structure © Gary E. Kaiser

Bacteriophages are viruses that infect bacteria.

Viruses cannot reproduce or express their genes without the help of a host. Viruses that kill their infected host cell are called virulent.

The DNA in these type of viruses is reproduced through the lytic cycle.

In the lytic cycle, the virus breaks open, or lyses, their host cell, resulting in the destruction of the host.

These animated images reveal the process of the lytic cycle in bacteriophages.

• A bacteriophage attaches to the cell wall of a bacterium.


• The bacteriophage injects its genome into the bacterium.


• The viral genome is replicated.


• Bacteriophages are released by lysis.

Learn more about viruses, see:

• Viruses