VIRUSES

When student took college biology twenty-five years ago, they were taught that one celled animals and plants were the simplest living things that existed . But more recently , scientists realized that there is an even simpler form of life –viruses. Viruses causes mumps, measles, rubella (German measles), smallpox, and number of other disease.

Viruses have a mysterious ability to exist and proliferate without carrying out the life functions of respiration and metabolism as we usually think of these functions. Viruses are parasites of cell and live within the cell themselves. Some scientist doubt that they should even be considered totally living things.

What viruses do is reproduce. A single virus is nothing more than a bit of nucleic acid within a protein coat. Nucleic acid is the biochemical substance that caries genetic information –the information an organism needs in order to produce more organisms just like itself. There are two kinds of nucleic acid, RNA and DNA; a virus contains one of these, but never both.)

Thus a Virus is really just a machine designed to duplicate itself . In fact, a virus is best defined as a microorganism that can reproduce only in living cells of a person or animal.

Once inside a cell, a virus takes over the cell’s machinery and directs it to produce many hundreds of new viruses. The cells, thus engorged with new viruses, break a part and spews its contents in all directions. Each new virus can enter another cell, capture its machinery, and start the cycle again.

Viruses don’t’ seem to be affected by antibiotics: once an individual has contracted a viral infection, drugs will not help fight the infection, nor will they cure it. But there is a brighter side to the picture: When exposed to some viruses , the body produces its own protective substance to help ward the Virus off. The substance is called interferon.