Viruses Are Infectious Agents That Can Not Do Anything Without A Host Cell

Viruses Are Infectious Agents That Can Not Do Anything Without A Host Cell

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Viruses are infectious agents that cannot do anything without a host cell. To give a brief summary, viruses have a protein coat called a capsule and they are not alive, nor are they cells. In addition, they do not have to be DNA based, but they can be RNA based as well. They cannot reproduce or carry out metabolism outside of a host cell and while eukaryotes are roughly around 10x the size of prokaryotes, prokaryotes are 10x the size of viruses. Furthermore, viruses that infect mammals tend to have an outer envelope which is outside of the protein coat that came from the cell that they last infected (they exocytose out of the cell and take some of the cell’s membrane with it). Additionally, antibiotics are not effective towards viruses because antibiotics are made to work against bacterial infections, however vaccines are known to be useful because they can prevent viral infections. This is because vaccines are made of parts of the virus that would stimulate an immune response as if the virus was actually there. This will cause the body to create antibodies so that if you were to really be exposed to it, your body can quickly react to it.
An experiment was conducted by Martinus Beijerinck in the late 1800s where sap from an infected tobacco plant with tobacco mosaic disease was extracted before being placed in a filter. The filter used is known to trap bacteria so that anything smaller than bacteria would pass through the filter. The filtered sap was then rubbed onto healthy tobacco plants in which they later became infected with tobacco mosaic disease as well. Based on this experiment, it was concluded that the infectious agent was not a bacterium since bacteria couldn’t go through the filter.
In order for viruses to get into a...


... middle of paper ...


...time, the viral DNA can separate from the bacterial chromosome and start the lytic cycle.
Additionally, HIV is covered by an envelope that was from a previous host cell membrane. At the start of its replication, glycoproteins which are on the outside of the envelope, bind to the receptor molecules of the host cell where it will fuse with it. Reverse transcriptase makes DNA from the two viral RNA strands and the DNA becomes a part of the chromosomal DNA where it is there permanently and called provirus. The provirus may be transcribed to mRNA to make HIV proteins or genetic material for the newly made viruses. Meanwhile, vesicles are used to transport glycoproteins to the cell’s plasma membrane. Moreover, protein coats form around the RNA and the reverse transcriptase molecules. Lastly, the viruses bud from the host cell, taking glycoproteins from the envelope with it.

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