Life Structure and Function

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Life Structure and Function

• 2.3 Virus

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Virus
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Virus

• A virus is a strand of hereditary material
  surrounded by a protein coating. Viruses dont
  have a nucleus, other organelles, or a cell
  membrane.
• All viruses can do is make copies of themselves.
• They cant do that without the help of a living
  cell called a host cell.

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Virus
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Virus

• Then, if they enter an organism, they can
  multiply quickly.
• It can either be active or it can become latent,
  which is an inactive stage
• When a virus enters a cell and is active, it
  causes the host cell to make new viruses.

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Virus
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Virus

• A virus cannot move by itself, but it can reach a
  hosts body in several ways.
• It can be carried onto a plants surface by the
  wind or it can be inhaled by an animal.
• In a viral infection, the virus first attaches to
  the surface of the host cell.

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Virus
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Virus

• The virus and the place where it attaches must
  fit together exactly.
• Because of this, most viruses attack only one
  kind of host cell.
• A vaccine is made from weakened virus particles
  that cant cause disease anymore.

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Virus
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Virus

• Vaccines have been made to prevent many diseases,
  including measles, mumps, smallpox, chicken pox,
  polio, and rabies.
• Antibiotics treat bacterial infections but are
  not effective against viral diseases.

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Virus
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Virus

• Antibiotics treat bacterial infections but are
  not effective against viral diseases.
• Interferons are proteins that are produced
  rapidly by virus-infected cells and move to
  noninfected cells in the host.
• Interferons cause the noninfected cells to
  produce protective substances.

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Virus