We know from childhood that when you come home, you should definitely wash your hands, as there are a lot of bacteria. Then, having matured a little, we often hear from parents about the dangers of viral infections. On TV we are told about the threat of bacterial weapons. It seems that viruses and bacteria are the most terrible and ubiquitous enemies of humanity. But what is the difference between a virus and a bacterium?
In fact, viruses and bacteria can live in conditions that are unacceptable for the existence of any other living organism. However, not only harm comes from them. Scientists have obtained viruses that can destroy cancer cells in humans. Bacteria help keep our planet from turning into one big dump by recycling household waste.
The virus is the most primitive form of life . Viruses do not have a cellular structure and, thus, cause a lot of controversy about their relationship to living or non-living organisms (see The difference between living and nonliving ).
Bacteria are unicellular organisms. The structure of this cell is more primitive than the cells of animals or plants, and, moreover, of a person. However, they can already be safely attributed to the living.
The size of the bacteria, on average, ranges from 0.0005mm-0.003mm. While the size of a common virus does not exceed 0.0003mm. However, both bacteria and viruses have their own "giants" and "dwarfs". The largest viruses are about 0.00035 mm in size, while the smallest bacteria are no more than 0.00015 mm. Among bacteria, there are also such "giants" that are clearly distinguishable by the naked human eye. So the bacterium Thomargarite, which lives on the seabed, has a size of 0.75mm.
The structure of a primitive virus is a molecule or DNA or RNA surrounded by protein molecules that create an envelope. More complex viruses can have a second, outer shell and even contain enzymes.
Bacteria, although primitive, but still real cells. And, although they do not have a nucleus as such, DNA in the form of a ball is located directly in the cytoplasm, there is a cell membrane with capsules, flagella and microvilli, RNA is present in the cell.
Since bacteria are cells, they are characterized by their own metabolism. Viruses have very few enzymes and do not have a metabolism
The virus invades only those cells where it can get through cell receptors. There it breaks down into nucleic acid and protein shells. These membranes attach to the cell membrane. From this moment on, all processes in the cell are controlled by the genetic information contained in the NK of the virus. The cell itself begins to synthesize viral proteins. Then, new viruses are formed from the newly formed nucleic acids and proteins, and the cell is destroyed.
Bacteria, like all cells, multiply by division. If a bacterium is disbanded in parts, as it happens with viruses, then it will no longer be able to recover.
- Viruses are precellular living organisms, while bacteria are unicellular.
- Viruses cannot reproduce outside living cells. Bacteria multiply independently by cell division.
- Viruses have only one type of nucleic acid, while bacteria include DNA, RNA, ribosomes, and a cell membrane.