Reference Terms
from Wikipedia, the free encyclopedia




A virus is a microscopic particle that can infect the cells of a biological organism.

Viruses can only replicate themselves by infecting a host cell and therefore cannot reproduce on their own.

At the most basic level, viruses consist of genetic material contained within a protective protein coat called a capsid; the existence of both genetic material and protein distinguishes them from other virus-like particles such as prions and viroids.

They infect a wide variety of organisms: both eukaryotes (animals, fungi and plants) and prokaryotes (bacteria).

A virus that infects bacteria is known as a bacteriophage, often shortened to phage.

The study of viruses is known as virology, and those who study viruses are known as virologists.

It has been argued extensively whether viruses are living organisms.

Most virologists consider them non-living, as they do not meet all the criteria of the generally accepted definition of life.

They are similar to obligate intracellular parasites as they lack the means for self-reproduction outside a host cell, but unlike parasites, viruses are generally not considered to be true living organisms.

A primary reason is that viruses do not possess a cell membrane or metabolise on their own - characteristics of all living organisms.

Examples of common human diseases caused by viruses include the common cold, the flu, chickenpox and cold sores.

Serious diseases such as Ebola, AIDS, bird flu and SARS are all also caused by viruses.

Note:   The above text is excerpted from the Wikipedia article "Virus", which has been released under the GNU Free Documentation License.
Related Stories



Plants & Animals News
August 8, 2020

When we say someone has a quick mind, it may be in part thanks to our expanded cerebellum that distinguishes human brains from those of macaque monkeys, for example. ...
Geological evidence suggests the known dinosaur groups diverged early on, supporting the traditional dinosaur ...
Scientists have discovered extinct strains of smallpox in the teeth of Viking skeletons -- proving for the first time that the killer disease plagued humanity for at least ...
Researchers conducted a first-of-its-kind study designed to investigate brain connectivity in 130 mammalian species. The ...
Latest Headlines
updated 12:56 pm ET