The Difference between Bacteria and Viruses

While antibiotics can be very effective against bacteria, they have no effect on viruses. The reason for this stems from the fact that although bacteria and viruses are both capable of causing infection, they are very different in some basic ways.

Bacteria are single-celled, independently living organisms. Many bacteria are helpful, and are found in plants, soil and water, as well as in animals, including humans.

Helicobacter pylori.

However, some bacteria can cause disease - for example, the bacterium Helicobacter pylori produces ulcers in some people, and many ear infections are due to the bacterium, Streptococus penumonia.

Viruses, on the other hand, are much smaller than bacteria and not able to survive independently. In order to reproduce, a virus must invade a living host cell, either by actually entering the cell or by injecting it with genetic material.

Examples of Viruses.

Once inside, the virus "takes over" and uses materials within the host cell to duplicate its own genetic information and creates a new crop of viruses. All living things - plant, animsla, and even bacteria - are vulnerable to viral infection. Examples of viral illnesses include the flu, caused by the Influenza virus,

Influenza virus life cycle.

and HIV, caused by a unique retro-type virus call the Human immunodeficiency virus.