According to C. Wese, all living things are divided into several domains. There are three of them: bacteria, archaea, and eukaryotes. Viruses are considered as a peerless category. The fact is that not all scientists attribute this group of beings to the living world. But the majority, as well as the creator of the hypothesis of the RNA world, tend to group viruses into a separate domain. And this, despite the fact that bacteria and viruses are the smallest in size among other creatures, and also quite simply arranged.
The question of the origin of viruses and bacteria remains open. There is not even an exact idea of which of these groups appeared earlier. It is logical to assume that viruses and bacteria should have a common ancestor and at least a unity of origin. The first theories were built on such judgments. But a detailed study of these microorganisms led to the conclusion that the differences between viruses and bacteria are more significant than previously thought.
The difference between viruses and bacteria
The most important of these differences is the way of life, which bacteria and viruses have completely different. The former, despite the simplicity of their device, are independent creatures. Even if they live inside the cell. As do, for example, chlamydia. Viruses outside the cell do not have any biological activity. They generally do not have any organs for elementary metabolism. A particle of all viruses consists of two elements. This is the genome (it is represented by one or two strands of ribonucleic acid) and the protein coat. Some have an extra capsid on top of the shell.
All viruses, depending on which ribonucleic acid they have, are divided into two large groups: RNA-and DNA-containing.
In the form of viruses, there may be several options.
- Icosahedrons.
- Phages.
- Octahedrons.
- Helical.
Bacteria and viruses are quite different in size. If the sizes of the first are measured in units and hundreds of micrometers, then the largest virus is no more than 1300-1400 nanometers. Thus, the largest virus is smaller than the smallest bacteria.
The pathogenicity of viruses depends on the ability to penetrate certain cells.
Whereas the existence of bacteria requires a combination of protection against aggression of the macroorganism and the ability to rapidly increase the number and formation of colonies. In other words: for bacteria, it is most important to “conquer” a certain living space for existence.
Accordingly, both bacteria and viruses have different sensitivity to drugs aimed at their destruction. As antiviral drugs, interferons and their analogues are most effective. To fight bacteria, antibiotics are used that do not act on viruses.
The entire life cycle of viruses can be described in several stages. First, the particle enters the cell. After that, the genome of the virus is embedded in the genome of the cell. The latter begins to produce copies of the virus, and cell organelles switch from their own metabolism to creating membranes for these genomes. Then the viral particles exit the cell, and everything starts anew.
Viruses pathogenic for humans cause measles, smallpox, rubella, polio, AIDS, colds of the upper respiratory tract and others. While bacteria are the culprits of whooping cough, diphtheria, typhoid, etc.