Virus
Virus is a very small microorganism, comparing with bacterium or mold.
The basic structure of virus is nucleic acid (DNA or RNA) surrounded by film of capsid.
Some viruses are covered over with the film called envelop, which contains protein, fat, and lipid. Virus itself has not independent metabolic function; therefore it isn’t able to multiply but infecting living host cells can multiply (replicate).
<Characteristics of each microorganism>
| Virus | bacterium | mold | |
| Size | 20～300ｎｍ | 0.5～1μｍ | 2～10μｍ |
| Biological Classification |
DNA or RNA and protein (non-cellular organisms) |
Microscopic spherical organisms involved in fermentation | Multicellular eukaryote |
| Cell membrane and cell wall | × | ○ | ○ |
| DNA and RNA | One of them | Both | Both |
| Propagation |
Do not multiply by itself. It infects the living host cells to multiply |
Multiplies by |
Multiplies by itself |
