Virus
From Simple English Wikipedia, the free encyclopedia
- This page is about biological viruses. For the computer term, see computer virus.
A virus is a small particle that can infect living organisms.
Viruses do not belong to any of the six kingdoms. They are generally seen as being between living organisms and inanimate nature, rather than alive, since they do not show all characteristics of living organisms.
Viruses are much smaller than bacteria. They can only be seen with an electron microscope. A virus has a simple structure. It has no internal cellular structure, no cell wall or cell membrane. They are only a protein coat that holds a coiled string of nucleic acid.
Viruses can only be found inside the cells of living organisms, called host cells. Therefore, they are parasites.
Viruses are too small to be seen by regular light microscopes]. They are on the molecular level. They have the following characteristics:
- Non-cellular particles, causing many types of disease;
- Contain nucleic acid core DNA or RNA;
- Surrounded by a protective protein coat;
- They are acellular;
- They are totally dependent on other organisms.
When a hidden virus attaches to a host cell, it becomes a part of the cell's genetic material, and may stay hidden for a long time, until the virus becomes active. This stage is known as the lysogenic phase.
