Viruses: Bacteriophages

Bacteriophage Structure © Gary E. Kaiser

Did you know that viruses can infect bacteria? These types of viruses are called bacteriophages. They are perhaps the best understood viruses, yet at the same time, their structure can be extraordinarily complex.

The use of bacteriophages was important in discovering that DNA in viruses can reproduce through two mechanisms: the lytic cycle and the lysogenic cycle. When viruses reproduce by the lytic cycle, they break open, or lyse, their host cells, resulting in the destruction of the host.

In the lysogenic cycle, the phage's DNA (viral DNA) recombines with the bacterial chromosome. Once it has inserted itself, it is known as a prophage. A host cell that carries a prophage has the potential to lyse, thus it is called a lysogenic cell.

To learn more about bacteriophages, see Bacteriophage Animations.