Ch 12 Viruses, Viroids, and Prions
Kelsey Pressler's Virtual Lectures・10 minutes read
Non-living pathogens like viruses, viroids, and prions cause infections in various organisms, with viruses depending on host cells for replication and differentiation based on genetic material and entry mechanisms. Prions, protein-based infectious particles, cause diseases like mad cow disease and require specialized methods like incineration for destruction.
Insights
- Viruses are acellular infectious particles smaller than bacteria, relying on host cells for replication and causing diseases like the common cold and HIV. They enter host cells through direct penetration, membrane fusion, or endocytosis, with differentiation based on genetic material and host specificity.
- Prions, protein-based infectious particles like those causing mad cow disease, are resistant to proteases and disinfectants, necessitating incineration or autoclaving for destruction. Their unique nature poses challenges in eradication compared to other non-living pathogens.
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Recent questions
What are non-living pathogens?
Viruses, viroids, and prions.
How do viruses replicate?
By relying on host cells' metabolic pathways.
What distinguishes enveloped viruses from naked viruses?
Enveloped viruses have an outer lipid membrane.
How do prions cause diseases?
By inducing spongiform encephalopathies.
What are the two replication cycles of bacteriophages?
Lytic and lysogenic cycles.
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Summary
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Understanding Non-Living Pathogens: Viruses, Viroids, Prions
- Non-living pathogens include viruses, viroids, and prions, which are acellular infectious particles causing various infections in humans, animals, plants, and bacteria.
- Viruses are smaller than bacteria, measured in nanometers, and can have either DNA or RNA, causing diseases like the common cold, influenza, and HIV.
- Viruses cannot replicate independently and rely on host cells' metabolic pathways, existing in extracellular and intracellular states with or without an envelope.
- Differentiation of viruses is based on their genetic material, host specificity, and mechanisms of entry into host cells like direct penetration, membrane fusion, or endocytosis.
- Animal virus replication involves recognition, attachment, entry, synthesis, and release of new viral particles through budding, exocytosis, or cell lysis.
- Enveloped viruses may cause persistent infections through budding, while naked viruses are released by exocytosis or lysis.
- Bacteriophage replication includes lytic and lysogenic cycles, with the latter allowing infected host cells to reproduce normally before induction triggers the lytic cycle.
- Prions, solely protein-based infectious particles, cause spongiform encephalopathies like mad cow disease and are resistant to proteases, UV light, and disinfectants, requiring incineration or autoclaving for destruction.
