Virus
From Wikipedia, a free encyclopedia written in simple English for easy reading.
- This page is about biological viruses. For the computer term, see computer virus.
A virus is a small particle that can infect other organisms.
Viruses do not belong to any of the six kingdoms. They are generally seen as being between living organisms and inanimate nature, as 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 consist of a protein coat which holds a coiled string of nucleic acid.
Viruses can live only inside the cells of living organisms, called host cells. Therefore, they are parasites.
Viruses are too small to be seen by conventional 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 and injects its genetic material, the genetic material becomes a part of the cells genetic material and may remain hidden for long periods of time until the virus becomes active. This stage is known as the lysogenic phase.
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