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Questions and Answers
What is virology?
The study of viruses
What is a virus?
A submicroscopic, parasitic agent consisting of nucleic acid surrounded by a protein coat
Viruses can replicate by themselves without a host cell.
False
What type of nucleic acid can viruses contain?
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What is host range?
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What is cell tropism?
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Which of the following are components of a virion?
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What are bacteriophages?
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All viruses have a protein coat.
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What shape can polyhedral viruses have?
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Match the following types of viruses to their descriptions:
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What is the term for the clearings formed by bacteriophages on a lawn of bacteria?
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What is the primary attachment component for bacteriophages to bacterial cells?
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Viral species share the same genetic information and ecological niche.
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Study Notes
Overview of Virology
- Virology is the scientific study of viruses.
- Viruses are submicroscopic, parasitic agents composed of nucleic acid enclosed by a protein coat.
- Require living host cells for replication, making them obligatory intracellular parasites.
General Characteristics of Viruses
- Multiply within host cells by hijacking the host's metabolic machinery.
- Lack ribosomes and ATP-generating mechanisms.
- Contain a specific type of nucleic acid, either DNA or RNA, which can be single or double-stranded and linear or circular.
- Protein coat, known as a capsid, can be enveloped or non-enveloped.
Host Range and Cell Tropism
- Host range refers to the variety of host cells a virus can infect.
- Most viruses exhibit cell tropism, infecting only specific cell types based on receptor interactions.
- Chemical interactions and specific receptor sites are essential for viral attachment.
- Bacteriophages infect bacteria, while animal viruses attach to receptor sites on plasma membranes.
Viral Size and Structure
- Viruses range in size from 20 nm to 1000 nm.
- Viral structure includes:
- Virion: a complete viral particle with nucleic acid, capsid, envelope, and spikes.
- Morphological types: helical, polyhedral, enveloped, and complex viruses.
Detailed Viral Composition
- Nucleic acid can either be DNA or RNA, functioning as the virus's genetic material.
- Capsid: protects nucleic acid, made of subunits called capsomeres, can have uniform or varying sizes.
- Helical viruses feature cylindrical capsids; examples include rabies and Ebola.
Envelope and Spikes
- Some viruses have envelopes made of lipids, proteins, and carbohydrates, derived from host cells.
- Spikes are protrusions on the viral surface that aid attachment to host cells and help identify the virus.
Complex Viruses
- Bacteriophages exhibit complex structures with distinct components:
- Sheath: protects and contracts to inject viral genetic material into the host.
- Baseplate: anchors tail fibers for attachment to host cells.
- Tail fibers: facilitate the binding of the virus to bacterial cell walls.
Viral Taxonomy
- Virus classification is based on genomic information and structural characteristics.
- Genus names end with "-virus," family names with "–viridae," and order names with "–ales."
- Viral species share genetic information and ecological niches; subspecies are numbered for distinction.
Isolation and Cultivation of Viruses
- Viruses cannot replicate outside of living cells, complicating detection and identification.
- Bacteriophages are the easiest to cultivate, with growth observable through plaque formation on bacterial lawns.
- Animal viruses can be grown in living organisms, embryonated eggs, or tissue cultures; monitoring is based on changes or mortality of cells or embryos.
Growing Animal Viruses
- Animal viruses may be cultivated in live animals or embryonated eggs, indicating viral presence through visible changes.
- Cell cultures serve as another method for viral propagation, allowing for detailed study and observation.
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Description
Explore the fundamental concepts of virology, focusing on the characteristics and behaviors of viruses. This quiz covers the nature of viruses, their replication processes, and their dependence on host cells for multiplication. Perfect for beginners in the field of virology.
