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Viruses. Basically lifeless until they enter a host cell. Use cell organelles to reproduce. Typically a protein capsule with DNA or RNA inside. Because of this, viruses are NOT considered to be a living thing. Viruses usually infect a specific host species.
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Viruses • Basically lifeless until they enter a host cell. • Use cell organelles to reproduce. • Typically a protein capsule with DNA or RNA inside.
Because of this, viruses are NOT considered to be a living thing. • Viruses usually infect a specific host species. • Often can only infect certain cells of host.
The Lytic Cycle: • Replication cycle of virus: • Attachment • Virus or its DNA/RNA enters host • Synthesis • Viral DNA/RNA instructs host to manufacture viruses
Assembly • New viruses are assembled • Release • New viruses are released as cell bursts The Lysogenic Cycle: • Same as previous, but cells are not destroyed. • They continue to reproduce normally as they make viruses.
Mutation • Mutation of viral DNA can lead to new versions of a virus. • Like evolution. • Can also lead to cross-species infection. • Swine flu (H1N1, 2009) • 14, 286 deaths
Vaccination • Stimulate (train) your immune system. • Introduce a dead/weakened form of virus. • Immune cells learn to recognize and produce response (i.e. antibodies). • This allows a faster response when infected later.
