virology

Virology

Virology is the study of viruses, complexes of nucleic acids and proteins that have the capacity for replication in animal, plant and bacterial cells. 

 Viruses range in size from about 30 nm to about 450 nm, which means that most of them cannot be seen with light microscopes. 

While viruses reproduce and evolve, they do not engage in metabolism, do not move, and depend on a host cell for reproduction. The often-debated question of whether they are alive or not is a matter of definition that does not affect the biological reality of viruses, they cause many important infectious diseases, while it has been possible to prevent (certain) viral diseases by vaccination for a long time, A virus is a biological agent that reproduces inside the cells of living hosts. When infected by a virus, a host cell is forced to produce many thousands of identical copies of the original virus, at an extraordinary rate. Unlike most living things, viruses do not have cells that divide; new viruses are assembled in the infected host cell. Over 2,000 species of viruses have been discovered. A virus consists of two or three parts: genes, made from either DNA or RNA, long molecules that carry the genetic information; a protein coat that protects the genes; and in some viruses, an envelope of fat that surrounds and protects them when they are not contained within a host cell.

 references

http://en.wikipedia.org/