Virus Structure and Classification Quiz
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Questions and Answers

What are the main structural components of a virus?

  • Deoxyribonucleic acid and a carbohydrate layer
  • Ribonucleic acid and a lipid bilayer
  • A genome and a protein-containing structure (correct)
  • A protein coat and a lipid envelope

    • How do viruses differ in pathogenicity?

  • Pathogenicity is determined by the host organism rather than the virus
  • They all produce the same clinical pathologies
  • They can produce distinct clinical pathologies based on structural characteristics (correct)
  • All viruses have the same structural components which leads to similar pathologies

    • What is the typical size range of viruses compared to the cells they infect?

  • Approximately 100- to 1000-fold smaller than the cells (correct)
  • Identical in size to the cells they infect
  • Larger than cells by a factor of 10
  • Similar in size to small bacterial cells

    • Which of the following is NOT a characteristic used to define virus families?

    <p>Method of energy production</p> Signup and view all the answers

    What is a virion?

    <p>A virus particle that combines structural elements</p> Signup and view all the answers

    What is the diameter range of the smallest and largest human viruses?

    <p>20 nm to 300 nm</p> Signup and view all the answers

    What distinguishes a virus from a bacterial cell?

    <p>Viruses are smaller and pass-through filters designed for bacteria</p> Signup and view all the answers

    Which type of viral capsid symmetry might a virus exhibit?

    <p>Helical or icosahedral</p> Signup and view all the answers

    What is the primary characteristic that distinguishes Hepadnaviruses from other virus families?

    <p>They have an envelope that covers an icosahedral capsid.</p> Signup and view all the answers

    Which type of virus is known for causing latent infections?

    <p>Herpesviruses</p> Signup and view all the answers

    Which of the following viruses is classified as a Picornavirus?

    <p>Coxsackievirus</p> Signup and view all the answers

    What is a distinguishing feature of Poxviruses?

    <p>They have bricklike shapes and cause skin lesions known as 'pocks'.</p> Signup and view all the answers

    Which virus family is associated with respiratory tract disease and various infections?

    <p>Adenoviruses</p> Signup and view all the answers

    What is the diameter range of Hepadnaviruses?

    <p>42 nm</p> Signup and view all the answers

    Which characteristic describes Caliciviruses?

    <p>They are naked viruses with positive-polarity RNA.</p> Signup and view all the answers

    How many antigenic types are associated with Adenoviruses?

    <p>Over 40</p> Signup and view all the answers

    What differentiates the genera and species within a virus family?

    <p>Host range and serologic reactions</p> Signup and view all the answers

    Which of the following best describes the composition of helical capsids?

    <p>Made up of one type of polypeptide that assembles into a rod-shaped structure</p> Signup and view all the answers

    What is true about positive-strand RNA viruses?

    <p>They are of messenger RNA sense and can be used for protein synthesis</p> Signup and view all the answers

    What is the characteristic structure of reoviruses?

    <p>Naked viruses with two icosahedral capsid coats</p> Signup and view all the answers

    Which group does the rubella virus belong to?

    <p>Togaviruses</p> Signup and view all the answers

    Which capsid symmetry involves multiple types of polypeptides grouped into capsomers?

    <p>Icosahedral symmetry</p> Signup and view all the answers

    Which virus is primarily responsible for diarrhea in infants?

    <p>Rotavirus</p> Signup and view all the answers

    In terms of viral genomes, what distinguishes negative polarity RNA?

    <p>It is complementary to the messenger RNA sense</p> Signup and view all the answers

    What is the basic structural unit of helical capsids called?

    <p>Protomer</p> Signup and view all the answers

    What type of RNA does the hepatitis E virus possess?

    <p>Single-stranded positive-polarity RNA</p> Signup and view all the answers

    Which group contains human immunodeficiency virus (HIV)?

    <p>Retroviruses</p> Signup and view all the answers

    What role does the nucleocapsid play in viral structure?

    <p>It contains the viral nucleic acid and protomers</p> Signup and view all the answers

    Which virus is known as the main pathogen in orthomyxoviruses?

    <p>Influenza virus</p> Signup and view all the answers

    What type of genome is most commonly found in nature among viruses?

    <p>ssRNA and dsDNA</p> Signup and view all the answers

    What distinctive feature classifies paramyxoviruses?

    <p>Enveloped with helical nucleocapsid</p> Signup and view all the answers

    Which of the following statements is true about flaviviruses?

    <p>They include the hepatitis C virus</p> Signup and view all the answers

    What is the primary reservoir for the MERS coronavirus?

    <p>Bats</p> Signup and view all the answers

    What was the main mode of transmission for MERS to humans?

    <p>Close contact with camels</p> Signup and view all the answers

    During which month and year was COVID-19 declared a pandemic by WHO?

    <p>March 2020</p> Signup and view all the answers

    Which of the following symptoms is NOT commonly associated with COVID-19?

    <p>Vision problems</p> Signup and view all the answers

    What percentage of people infected with COVID-19 generally recover without special treatment?

    <p>80%</p> Signup and view all the answers

    What is a common characteristic of patients who tend to develop severe illness from COVID-19?

    <p>Older age</p> Signup and view all the answers

    What is the incubation period for COVID-19 as mentioned in the content?

    <p>1-14 days</p> Signup and view all the answers

    Which type of coronavirus is associated with the disease recognized in 2019?

    <p>SARS-CoV-2</p> Signup and view all the answers

    Which of the following viruses is NOT classified as a rhabdovirus?

    <p>Human immunodeficiency virus (HIV)</p> Signup and view all the answers

    What type of RNA do filoviruses contain?

    <p>Single-stranded, linear, nonsegmented, negative-polarity RNA</p> Signup and view all the answers

    What is the main transmission method for SARS?

    <p>Airborne transmission via droplets</p> Signup and view all the answers

    Which statement correctly describes coronaviruses?

    <p>They are responsible for diseases like COVID-19 and the common cold.</p> Signup and view all the answers

    What year did the severe acute respiratory syndrome (SARS) outbreak begin?

    <p>2002</p> Signup and view all the answers

    What is the primary natural reservoir for CoV-SARS?

    <p>Horseshoe bat</p> Signup and view all the answers

    Which coronavirus is known as SARS-CoV-2?

    <p>The virus responsible for COVID-19</p> Signup and view all the answers

    Filoviruses are characterized by their:

    <p>Pleomorphic and long filamentous shapes</p> Signup and view all the answers

    Study Notes

    Medical Important Viruses

    • Viruses are infectious agents composed minimally of a genome (RNA or DNA, but not both) and a protein capsid for protection.
    • Some viruses have additional features like an envelope, a lipid bilayer with proteins.
    • A complete virus particle is called a virion.
    • Viruses replicate inside host cells.
    • Viral pathogenicity varies greatly, even within a related virus family.
    • Viruses have different sizes and structures that define viral families, genera, and species.

    Virus Structure

    • Viruses are significantly smaller than host cells, ranging from 20 nm to 300 nm.
    • The small size allows them to pass through filters designed to trap bacteria. This lack of a cell wall is a distinguishing feature.
    • Viruses can be categorized as naked (no envelope) or enveloped (with an envelope).

    Virus Classification

    • Viruses are classified into groups based on their genome type (DNA or RNA, single-stranded or double-stranded), genome symmetry (helical or icosahedral), and presence of an envelope.
    • The Baltimore classification further categorizes viruses based on the way they produce mRNA.

    Virus Replication

    • Virus replication involves a series of steps including attachment to a host cell, penetration, uncoating, gene expression and replication, assembly, and release of progeny virions.
    • Not all steps are the same for every virus.
    • The individual steps in the viral replication cycle vary depending on the type of virus.

    Viral Capsid Symmetry

    • The protein shell (capsid) enclosing the viral genome can be either helical (rod-shaped) or icosahedral (spherical).
    • This capsid structure is constructed from multiple copies of a single or a few different polypeptides.

    Viral Envelopes

    • An envelope is a lipid bilayer membrane enclosing some viruses.
    • It is derived from the host cell membrane and contains viral proteins, providing virus-specific antigenicity.
    • Viruses without envelopes are called naked viruses.

    Viral Genomes

    • Viral genomes can be DNA or RNA, single-stranded or double-stranded.
    • The genome type is a major factor in virus classification.
    • Viral genomes can have positive or negative polarity regarding viral direction and function within mRNA production.

    Types of Viruses and Diseases

    • Each type of virus causes specific diseases.
    • For example, herpesviruses cause herpes, poxviruses cause smallpox.
    • Various families are studied: Adenovirus, Papovavirus, Hepadnavirus, Retrovirus etc.

    Molecular Tests

    • Diagnostic tests include tests using nucleic acid or antibody detection to understand viral presence/activity, exposure, etc.

    Covid-19

    • Covid-19 is a disease caused by SARS-CoV-2.
    • It displayed various symptoms, such as fever and dry cough.
    • The virus replicated in a manner to produce progeny virions, infect respiratory tracts, and enter the blood stream.
    • Different types of vaccines were developed based on mRNA, inactivated viruses, viral vector, or protein-based platforms.
    • There are several variants of the virus, including Alpha, Beta, Gamma, Delta, and Omicron.
    • Prevention involves handwashing, avoiding contact with sick people, wearing a mask, and avoiding crowded places.

    Summary

    • Viruses are classified based on their genome type, symmetry, and presence/absence of an envelope.
    • The methods to detect and control viruses involve molecular and immunological approaches, including antibody and PCR tests.
    • The various types of viruses and diseases they cause have been studied.
    • The COVID-19 pandemic highlighted the role of viruses and the need for preventive measures.

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    Description

    Test your knowledge on the structural components of viruses and their classification! This quiz covers various aspects such as viral size, pathogenicity, and distinguishing features of different virus families. How well do you understand the complexity of viruses?

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