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Questions and Answers
What are viruses classified as due to their inability to reproduce independently?
What are viruses classified as due to their inability to reproduce independently?
Which component protects the viral genome from the environment?
Which component protects the viral genome from the environment?
What type of genetic material can viruses contain?
What type of genetic material can viruses contain?
What is a defining feature of helical viruses?
What is a defining feature of helical viruses?
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What happens during the lytic cycle of viral replication?
What happens during the lytic cycle of viral replication?
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What is the function of glycoproteins in enveloped viruses?
What is the function of glycoproteins in enveloped viruses?
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What distinguishes segmented genomes during genetic exchange?
What distinguishes segmented genomes during genetic exchange?
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Which type of viruses specifically infect bacteria?
Which type of viruses specifically infect bacteria?
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What is the primary characteristic of naked viruses?
What is the primary characteristic of naked viruses?
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What method do enveloped viruses typically use to enter host cells?
What method do enveloped viruses typically use to enter host cells?
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What defines whether a virus is classified as enveloped or naked?
What defines whether a virus is classified as enveloped or naked?
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Which of the following describes the lytic cycle of a virus?
Which of the following describes the lytic cycle of a virus?
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What occurs during reassortment in segmented viruses?
What occurs during reassortment in segmented viruses?
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What role do capsids play in viral structure?
What role do capsids play in viral structure?
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Which of the following is NOT a characteristic used to classify viruses?
Which of the following is NOT a characteristic used to classify viruses?
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What is the relationship between Hepatitis B and Hepatitis D?
What is the relationship between Hepatitis B and Hepatitis D?
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How do enveloped viruses typically enter host cells?
How do enveloped viruses typically enter host cells?
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Which method allows one functional virus to provide a component to a defective virus?
Which method allows one functional virus to provide a component to a defective virus?
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What is a significant outcome of the lysogenic cycle?
What is a significant outcome of the lysogenic cycle?
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Which viral family is responsible for causing influenza?
Which viral family is responsible for causing influenza?
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What characterizes phenotypic mixing in viruses?
What characterizes phenotypic mixing in viruses?
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What characterizes single-stranded RNA viruses?
What characterizes single-stranded RNA viruses?
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Which of the following describes a key feature of viruses?
Which of the following describes a key feature of viruses?
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What process allows genetic material exchange between two viruses?
What process allows genetic material exchange between two viruses?
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What is a common method used by both naked and enveloped viruses to enter host cells?
What is a common method used by both naked and enveloped viruses to enter host cells?
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What process do viruses potentially utilize to undergo genetic exchange?
What process do viruses potentially utilize to undergo genetic exchange?
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Which component of the virus binds to host cell receptors?
Which component of the virus binds to host cell receptors?
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What is a characteristic feature of enveloped viruses like influenza?
What is a characteristic feature of enveloped viruses like influenza?
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Which of the following is NOT a method viruses use to exchange genetic material?
Which of the following is NOT a method viruses use to exchange genetic material?
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What does the lysogenic cycle involve in viral replication?
What does the lysogenic cycle involve in viral replication?
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Study Notes
Introduction to Virology
- Viruses are acellular entities, meaning they are not cells and cannot reproduce independently.
- They are obligate intracellular parasites, requiring a host cell to replicate and produce proteins.
- Viruses are essentially packages of nucleic acids, either DNA or RNA, but never both.
Viral Structure
- Capsid: A protein coat surrounding the genome, protecting it from the environment.
- Nucleocapsid: The capsid and the genetic material within.
- Envelope: Some viruses have a lipid membrane surrounding the capsid, containing glycoproteins for attachment to host cells.
Viral Classification
-
Genome Composition:
- Type of nucleic acid: DNA or RNA viruses.
- Number of strands: Single-stranded or double-stranded DNA/RNA.
- Genome geometry: Linear or circular.
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Capsid Structure:
- Helical: Capsid proteins arranged in a helical pattern, like a tube.
- Icosahedral: Proteins arranged in equilateral triangles, forming a 20-sided structure.
- Complex: A combination of helical and icosahedral structures.
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Presence of Envelope:
- Naked: No envelope present
- Enveloped: Surrounded by a lipid bilayer envelope.
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Host Type:
- Bacteriophages: Viruses that infect bacteria.
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Method of Action:
- Tail-like: Used by bacteriophages to inject their genetic material into the host.
- Direct Fusion: Enveloped viruses fuse with the host cell membrane.
- Receptor-mediated endocytosis: Viruses, both naked and enveloped, enter the cell through receptors.
Viral Replication
- Lytic Cycle: The virus uses the host cell's machinery to replicate and produce new virus particles, causing the cell to lyse (rupture).
- Lysogenic Cycle: Viral genetic material integrates into the host cell's genome (provirus), remaining dormant. The host cell replicates, carrying the viral genetic material. This cycle can trigger the lytic cycle, causing the release of new viruses.
Viral Genetic Exchange
- Recombination: Two viruses enter a host cell, their genetic material mixes, and they exchange DNA/RNA segments.
- Reassortment: Occurs with segmented genomes (e.g., influenza viruses). Genetic material is exchanged between different segments of the virus.
- Complementation: One functional virus provides a missing component (e.g., capsid) to a defective virus.
- Phenotypic Mixing: Two functional viruses exchange capsids; both viruses remain functional.
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Description
This quiz explores the fundamental concepts of virology, including the nature and structure of viruses. Understand the classification based on genome composition and capsid structure. Test your knowledge on how viruses operate as obligate intracellular parasites and the roles of different viral components.
