Transcript Viruses

Viruses
Viruses
• Use infected cell to produce more viruses
• Capsid: protein coat surrounding
DNA/RNA core
• bacteriophage – virus that infects bacteria
Viral Infections
Lytic Infection
• after entering the cell, host cell make 1000’s
of copies of viruse’s DNA
• new virus particles are made
• the infected cell then lyses, or busts
• 100’s of virus particles are released
Viral Infections
Lysogenic Infection
• Prophage: viral DNA
become part of the host’s
DNA
• viral DNA is copies with
host’s DNA
• When the prophage is
activated, the cell enters
the lytic cycle
Retroviruses
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RNA
In host cell, makes a DNA copy of RNA
its DNA is inserted into the host’s DNA
AIDS
Are Viruses Alive?
• Not Alive
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no response to the environment
does not obtain or use energy
no growth or development
reproduces only with a host cell