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Questions and Answers
What term is used to describe the complete, mature, and infectious particle of a virus?
What term is used to describe the complete, mature, and infectious particle of a virus?
Which of the following best describes the components of a typical virion?
Which of the following best describes the components of a typical virion?
What is the primary function of the viral capsid?
What is the primary function of the viral capsid?
Which structure is NOT a potential shape of a viral capsid?
Which structure is NOT a potential shape of a viral capsid?
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What characteristic do capsomeres exhibit?
What characteristic do capsomeres exhibit?
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Which of the following shapes is NOT associated with viral capsids?
Which of the following shapes is NOT associated with viral capsids?
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What is one of the primary functions of a viral capsid?
What is one of the primary functions of a viral capsid?
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Enveloped viruses are characterized by their lipid bilayer derived from what source?
Enveloped viruses are characterized by their lipid bilayer derived from what source?
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What role do tail fibers play in some viruses?
What role do tail fibers play in some viruses?
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Which statement best describes the function of spikes in viruses?
Which statement best describes the function of spikes in viruses?
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Study Notes
Virus Structure and Shapes
- The complete, mature, and infectious viral particle is known as a virion. A typical virion is composed of the following parts:
- Outer Coat:
- Capsids (inner core)
- Envelope (tail fibers/spikes)
- Inner Core:
- DNA or RNA (genome)
- Reverse transcriptase (in some cases)
Genome
- The genome is the total genetic material, also called the nucleoid
- It's made up of single or many DNA or RNA molecules
- Smaller viruses have one genome molecule, larger viruses have several hundred
- Viral proteins are also present, which have an interactive role with host cell components
- Genomes encode genetic information for replication, transcription, translation, viral assembly, viral release, host-virus interactions, and immune evasion
- Types of genomes include DNA, RNA, and reverse transcriptase
Capsid
- The capsid is the protein coat surrounding the genome
- It's made up of protein subunits called capsomers.
- Capsomer shapes vary among different viruses (e.g., Adenovirus - 252, Rhinovirus - 180, Poliovirus - 180, Rotavirus - 200, Hepatitis virus - 120, HIV - 200, Bacteriophage T4 - 115, TMV - 2130)
- Variations in capsids include icosahedral (20 sided), helical (cylindrical), complex (combination of icosahedral and helical), flexible, pleomorphic (irregular), variable shapes (spherical, prolate (elongated), oval, shape, oblate (flattened), click-like shape), tadpole (oval shaped head with tail), polyhedral, etc.
Functions of Capsid
- Stability, protection, attachment, penetration, assembly, and fusion with host membrane
- Some viruses have accessory structures called viral envelopes (or cloaking or covering), classifying them as enveloped or unenveloped viruses.
- Enveloped viruses have a host-derived membrane composed of a lipid bilayer and glycoprotein spikes, envelope proteins and surface antigens facilitating attachment to host cells, entry into host cells, fusion with host membranes, immune evasion, viral assembly, viral release by budding
Tail Fibers/Spikes
- These are additional fibers
- Some viruses have tail fibers
- These are long protein structures extending from the viral tail
- Composed of fibrous protein (like collagen fibers)
- Short, spike-like protein structures that are located on the viral tail or surface
- Composed of glycoprotein
- Functions of tail fibers/spikes:
- Host Recognition
- Attachment to host cells
- Adsorption to host cells (initial binding to the host)
- Penetration to host cells
- Genome delivery
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Description
Explore the intricate details of virus structure, including the composition of virions, genomes, and capsids. This quiz covers the various components that make up viral particles, their genetic material, and how they interact with host cells. Test your knowledge on the types of viral genomes and their functions.
