Viruses Lecture 11 PDF
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Summary
This lecture covers the basics of viruses, including their structure, categories, and the lytic cycle. It explores whether viruses are considered living organisms and their ability to infect animal, plant, bacterial, and human cells.
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# Viruses ## Dead or alive? ## Viral structure - Viruses are not cells. - Basic structure: - Protein coat (highly antigenic) - Nucleic acid core (RNA or DNA) - Lipoprotein coat - (second coat - only in enveloped viruses) ## Virus Categories - **DNA viruses** - stable, do not...
# Viruses ## Dead or alive? ## Viral structure - Viruses are not cells. - Basic structure: - Protein coat (highly antigenic) - Nucleic acid core (RNA or DNA) - Lipoprotein coat - (second coat - only in enveloped viruses) ## Virus Categories - **DNA viruses** - stable, do not mutate rapidly - Single-stranded or double-stranded - Smallpox, Hepatitis B - **RNA viruses** - mutate rapidly, unstable - Single-stranded or double-stranded - HIV, Rhinovirus ## Are viruses alive? - Only 1 characteristic of life: reproduction - Can only reproduce inside a host cell! - Process or reproduction = lytic cycle ## Lytic Cycle - Virus attaches to host cell's membrane and injects its nucleic acid into the host cell. - The viral nucleic acid takes over protein synthesis, creating new viruses. - The host cell bursts, lyses, releasing the newly formed viruses. ## Cells subject to viral attack - Viruses may attack: - Animal cells - Plant cells - Bacterial cells - Human cells
