What is the difference between a virus and a bacterium?

Discovery Health

The body is a multi-cellular organism made up of about 100 trillion cells. These cells are fairly complicated machines. Each has a nucleus, energy production equipment, etc. Bacteria, on the other hand, are single-celled organisms that are much simpler. They do not even have a nucleus. They are perhaps 1/100th the size of a cell.

Bacteria are independent organisms able to eat and reproduce on their own. They are sort of like fish swimming around in the ocean of your body. Under certain conditions bacteria reproduce very quickly: One bacterium divides into two separate bacteria perhaps once every 20 to 30 minutes. At that rate, one bacterium can become millions in just a few hours.

Viruses are different breeds altogether. A virus is not really alive. The virus particle is nothing but a fragment of DNA wearing a protective coat. The virus connects with a cell, attaches itself to the cell wall then injects its DNA (and maybe a few enzymes) into the cell. The virus's DNA uses the machinery inside the living cell to create new virus particles. Eventually the hijacked cell dies at which point it bursts, freeing the new virus particles. Sometimes, the viral particles may bud off the cell so it can remain alive. In either case, the virus uses a cell like a factory.

Continue Learning about Viral Infections

Viral Infections

Viral Infections

Viral infections like herpes simplex, respiratory syncytial virus (RSV), chicken pox and rotavirus are infections caused by a virus instead of a bacterium. Viral infections do not respond to antibiotics, but some specific viruses ...

like influenza A and B can be treated with certain antiviral medications. Most commonly, treatment for viral infections includes drinking lots of fluids, getting rest, eating well and letting the illness run its course.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.