Transcript Viruses - The Fenn School

Viruses
By Aaron Colby, Andrew Hack,
and Chris Seward
Table of Contents
Structure
Feeding
Reproduction
Species
Viral Structure
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<½ m diameter
Antigens
Envelope
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DNA or RNA
capsid
Made from dead host cell
membrane
Not all viruses
Capsid
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antigens
Protects the virion’s contents
Made of capsomeres
envelope
enzymes
Enzymes
DNA or RNA, Genome
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Controls growth, reproduction,
etc.
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Viral Reproduction
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Entry: A virion attaches to a host
cell.
Absorption : The virion releases
its DNA or RNA into the host cell.
Reproduction: The viral DNA or
RNA is injected into the host’s
nucleus, starting the reproductive
process
Viral Reproduction: The Cell
produces all the parts needed for
many new virions
Assembly: The new parts are
assembled into new virons.
Release: The new virons break
free from the host cell either by
breaking out, which destroys the
cell or by pinching out which
doesn’t.
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Viral Feeding
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Viruses do not feed
because they are not
living things.
Viruses are only
active when inside a
host cell
Viruses use host cell
to produce more
viruses
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Major Phyla & Viral Species
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There are many species of viruses.
Icosahedral, Helical, Bacteriophage
Viruses are categorized by physical
features and host cells
Nucleic Acid
Capsid Shape
Envelope
Host Type
Examples
RNA
Many-sided
Absent
Animal
Poliovirus
Present
Animal
AIDS virus
Absent
Plant
Tobacco Mosaic Virus
Present
Animal
Flu virus
Absent
Animal
Cold viruses
Present
Animal
Herpesviruses
Rod
Absent
Bacteria
Some bacterial viruses
Complex
Absent
Bacteria
Some bacterial viruses
Present
Animal
Smallpox virus, chicken pox virus
Rod
DNA
Many-Sided
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© 2002 Chris Seward, Aaron Colby, Andrew Hack - All Rights Reserved
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This slide show provides good information about viruses
Remember that viruses are not made of cells and technically not
considered to be living things