bacterium v. virus
Sunday, January 10, 2010 Bacteria are unicellular, prokaryotic microorganisms, with typical sizes ranging from 500 to 5000 nanometers. Viruses are much smaller, 10 to 300 nm biological entities consisting of little more than a section of RNA or DNA enclosed in a protein coat.
Bacteria are living organisms that reproduce by splitting in a process known as binary fission. Viruses are believed to fall somewhere between living and nonliving, as they don’t grow, consume energy, or respond to their environment. To reproduce, a virus enters a host cell, and co-opts its metabolic machinery to make many copies of itself. The host’s cell membrane then bursts, allowing the virus to spread to other cells.
Most bacteria that live within larger organisms have a neutral or beneficial effect on their hosts, with only a small percentage of bacterial species being pathogenic. With the exception of some bacteriophages, which can infect undesirable bacteria, most viruses are harmful to their hosts.
Bacteria cause diseases such as cholera, anthrax, leprosy, tuberculosis, cat-scratch fever, and tetanus. Herpes, AIDS, the common cold, ebola, foot-and-mouth disease, plantar warts, rabies, and chickenpox are all viral. Bacterial infections can often be handled with antibiotics, which kill bacteria. Because viruses are found within cells, and not between them, as is the case with bacteria, viral infections are difficult to treat without damaging the host. Antiviral drugs alleviate symptoms, but don’t destroy the pathogen. Vaccines can also be employed to prevent viral infection.