How do viruses multiply?
Viruses do not have their own metabolism and are therefore dependent on their host; also with propagation. For this process they can go through either the lytic or the lysogenic cycle.
Structure of viruses and the lytic cycle
- Viruses consist of a head part in which their DNA is stored. The collar is attached to this head as a transitional component, and finally the body at. This consists of a tail sheath, tail pin, tail thread and spikes.
- In the first phase, the so-called adsorption, the spikes are used to attach to the host cell. Depending on the type, a cell has different receptors on its surface. Viruses have specialized in these special docking points, so that not every virus can attack every cell. In accordance with the lock and key principle, this is only possible for viruses that match the cell. For this reason, an infection is always host-specific.
- In phase 2, the injection, it is now the task of the tail pin to deliver the DNA in the virus head like when placing a syringe. In order for this to happen, the tail sheath under the tail pin contracts and expands again. In this way, the genetic material is "shot" into the host cell.
- In the latency phase, the virus DNA infiltrated into the system now provides the complete metabolism rearranged the host cell. The actual genetic material of the host is broken down and the cell's metabolism is used for virus replication.
- In the fourth phase of maturation, the individual components of the virus (head, collar, etc.) are produced individually and put together according to instructions, as in a construction kit.
- Phase 5 is the release. An enzyme that has already been produced in phase 3 is now activated and destroys it. Hence the name of this cycle, because the Greek word "lysis" means "dissolution". The host cell practically bursts apart and releases the newly created viruses to the outside.
- This entire cycle takes place in a very short time, which means that the host cells have little opportunity to defend themselves.
Viruses and bacteria are pathogens that infect people with diseases. …
Propagation by means of the lysogenic cycle
- In contrast to lytic reproduction, the virus initially refrains from destroying the infected host cell shortly after infection. Rather, after the DNA has implanted, it falls into a kind of "sleep".
- Phases 1 and 2 are identical in the lysogenic and lytic cycle: first adsorption and then injection. Instead of adjusting the host's metabolism to the virus needs in the third phase, the virus DNA is only integrated and does not issue any further commands.
- In this "dormant state", however, the virus DNA is passed on to its daughter cells with every healthy multiplication of the host cell. With each cell division, the virus rests in more and more apparently healthy cells.
- Only when the external conditions are right (these can be very different stimuli from the environment) do the dormant virus genomes become active and also change the metabolism of their hosts. As with the lytic cycle, the host bursts apart once active reproduction is complete.
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