Viral Structures and Function
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Capsids are protein shells that protect Viral DNA or RNA. Capsids come in a variety of shapes including the basic helix structure of the tobacco mosaic virus and the icosahedral of the adenoviruses. The individual proteins that make up a capsid are called capsomeres.
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Being parasitic in nature, there are many ways viruses have adapted to evade bodily defenses and to gain access into a host cell. It is not uncommon for viruses to surround themselves in a membrane envelope. This membrane is derived from the phospholipid bilayer of a previous host cell. Because of this, the virus isn't recognized as a harmful pathogen. On the left is a visual representation of this effect.
Embedded in the membrane of many cells are receptors that recognize and facilitate phagocytosis of beneficial molecules. Viruses can take advantage of this by using special glycoproteins that closely resemble the desired substance that the receptor is meant to accept. Now the host cell readily transports the virus inside the membrane.
Embedded in the membrane of many cells are receptors that recognize and facilitate phagocytosis of beneficial molecules. Viruses can take advantage of this by using special glycoproteins that closely resemble the desired substance that the receptor is meant to accept. Now the host cell readily transports the virus inside the membrane.