7th grade life science section 2

1. VIRUSES
Chapter 7 Section 1

2. Characteristics of Viruses
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Tiny (smaller than cells)
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Non living
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Enters a living cell and reproduces
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No organisms are safe
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Can multiply only when inside a living cell

3. HOST
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Organism that a virus enters and multiplies
in
Provides a source of energy for a virus or
another organism

4. PARASITE
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Organism that lives on or in a host
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Causes harm to its host
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Destroys the cells in which they multiply

5. VIRUS SHAPES
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Round
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Rod-shaped
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Bricks
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Threads
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Bullets
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Robot Shape (Bacteriophage)

6. STRUCTURE OF VIRUSES
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Two basic parts
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Protein Coat-protects virus
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Inner Core -made of genetic material

7. PROTEINS
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Play an important role during invasion of
host
Allows the virus to attach to certain cells
Fit only into certain locks on the surface of
host
Allows certain viruses to only attach to
certain cells.

8. How Viruses Multiply
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Attaches to host
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Enters cell
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Genetic material takes over cell functions
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Instructs cell to produce
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Sometimes happens immediately
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Sometimes takes a while

9. ACTIVE VIRUSES
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Immediately goes into action
Cell quickly begins to produce protein and
genetic material
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Like a photocopy machine left in on position
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Makes copy after copy until host cell is full

10. HIDDEN VIRUSES
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Do not immediately become active
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Hide for a while
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Does not affect the cells functions
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Can stay inactive for years
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As host cell divides the genetic material of
virus is copied as well
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Under certain conditions becomes active
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Example: Cold Sore

11. Viruses & Disease
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Some like colds are short lived.
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Other like AIDS have much more serious
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Can cause disease in Trees, Pets

12. Usefulness of Viruses
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Gene therapy- use virus as messenger to
give cells what they need
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Shows promise in disorders like cystic fibrosis
where patience lack genetic material they need
to keep lungs functioning properly. Gene
therapy delivers genetic material needed by the
lungs.