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Viruses (Living Thing)
built 178 days ago
Viruses (Living Thing) also shows up in the Retriever categories:
Viruses (Malicious Software) , and more.
Viruses (Malicious Software) , and more.
Viruses and aberrant prion proteins are often considered replicators rather than forms of life, a distinction warranted because they cannot reproduce without very specialized substrates such as host cells or proteins, respectively. Also, the Rickettsia and Chlamydia are examples of bacteria that cannot independently fulfill many vital biochemical processes, and depend on entry, growth, and replication within the cytoplasm of eukaryotic host cells. However, most forms of life rely on foods produced by other species, or at least the specific chemistry of Earth's environment.
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Viruses are very small, ranging in size from 20 nanometers to 250 nanometers. A nanometer is equal to 0.00000004 inch (4X10-8 in). The smallest of all bacteria is about the size of the largest virus. This picture shows round virus particles along with rod-shaped bacteria cells.
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Viruses' protein coats have varying durability, causing some to become unable to reproduce in fairly short order if exposed to a foreign environment. Other viruses can remain virulent under a wide range of conditions for great lengths of time.
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Viruses reproduce only within living cells. They attach to the plasma membrane of the host cell and release their nucleic acid into the cytoplasm of the cell. The capsid may remain outside the cell, or it may be digested by the host cell within the cytoplasm. In the host cytoplasm, the DNA or RNA of the viral genome encodes the proteins that act as enzymes for the synthesis of new viruses. The enzymes use amino acids in the cell for protein synthesis and nucleotides from the host DNA for nucleic acid synthesis. The viruses obtain cellular ATP and use cellular ribosomes for additional viral synthesis.
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Viruses are usually easy to destroy while outside living organisms. Outside the body, the "AIDS" virus, HIV, can be destroyed with a solution of bleach that is almost weak enough for you to drink. But once inside a host, most substances that destroy the virus are ... harmful to the host organism. For this reason, viral infections in animal cells can be extremely hard to cure. Viral infections in plant cells are almost impossible to cure.
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Viruses can cause a number of human diseases, including measles, mumps, chickenpox, AIDS, influenza, hepatitis, polio, and encephalitis. Protection from these diseases can be rendered by using vaccines composed of weak or inactive viruses. A viral vaccine induces the immune system to produce antibodies, which provide long-term protection against a viral disease.
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Viruses (Living Thing)