Unveiling the World of Viruses
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Questions and Answers

Which of the following is NOT a criteria for classification of viruses?

  • Morphology
  • Host organism
  • Cellular structure (correct)
  • Genome type
  • What is the difference between +ssRNA and -ssRNA?

  • The presence of a protein coat
  • The presence of an envelope
  • The size of the RNA molecule
  • The orientation of the RNA strand (correct)
  • What is the key enzyme involved in retrovirus function?

  • Ligase
  • RNA polymerase
  • DNA polymerase
  • Reverse transcriptase (correct)
  • Which of the following is NOT a component of a virus?

    <p>Cell membrane</p> Signup and view all the answers

    What are the three forms of a capsid?

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

    What is the difference between virulent and temperate phages?

    <p>Virulent phages always cause lytic infections, while temperate phages can cause both lytic and lysogenic infections</p> Signup and view all the answers

    What is uncoating in the context of viral replication?

    <p>The process of disassembly of the viral capsid</p> Signup and view all the answers

    How do enveloped and non-enveloped viruses differ in terms of penetration?

    <p>Enveloped viruses enter the host cell through fusion with the host cell membrane, while non-enveloped viruses enter the host cell through receptor-mediated endocytosis</p> Signup and view all the answers

    What is a retrovirus?

    <p>A virus that uses reverse transcriptase to convert its RNA genome into DNA</p> Signup and view all the answers

    How are animal viruses cultivated?

    <p>In both fertilized chicken eggs and cell cultures</p> Signup and view all the answers

    How are bacteriophages cultivated?

    <p>In bacterial cultures</p> Signup and view all the answers

    What are plaques in the context of viral replication?

    <p>Clear zones on a lawn of host cells indicating areas of viral infection and cell death</p> Signup and view all the answers

    How do scientists detect viruses?

    <p>By observing cytopathic effects such as syncytia and cell inclusions</p> Signup and view all the answers

    Which of the following is NOT a step of bacteriophage replication?

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

    What is the difference between +ssRNA and -ssRNA?

    <p>The polarity of the RNA strand</p> Signup and view all the answers

    What is a bacteriophage?

    <p>A virus that infects bacteria</p> Signup and view all the answers

    What would cause a temperate phage to switch to the lytic cycle?

    <p>Presence of certain environmental conditions</p> Signup and view all the answers

    What is meant by host range?

    <p>The number of different host organisms a virus can infect</p> Signup and view all the answers

    What are the criteria for classification of viruses?

    <p>Host organism, morphology, genome type</p> Signup and view all the answers

    What is a viral growth curve?

    <p>A graphical representation of the different stages of viral infection in a host</p> Signup and view all the answers

    How are animal viruses cultivated?

    <p>Fertilized chicken eggs, cell cultures</p> Signup and view all the answers

    What are virioids?

    <p>Small infectious RNA molecules</p> Signup and view all the answers

    What are virusoids?

    <p>Small infectious RNA molecules</p> Signup and view all the answers

    Study Notes

    Virus Classification

    • Criteria for classification of viruses do not include shape, size, and other physical characteristics.

    RNA Viruses

    • +ssRNA viruses have a single-stranded RNA molecule that can act as messenger RNA, while -ssRNA viruses have a single-stranded RNA molecule that must be transcribed into mRNA.
    • Retroviruses are a type of -ssRNA virus that uses the reverse transcriptase enzyme to convert its RNA genome into DNA.

    Virus Structure

    • A virus does not have a cellular membrane.
    • The three forms of a capsid are helical, icosahedral, and complex.

    Phages

    • Virulent phages always cause lysis, whereas temperate phages can enter a dormant state, called lysogeny.
    • Uncoating is the process of removing the viral protein coat, allowing the viral genome to be released into the host cell.

    Penetration

    • Enveloped viruses use membrane fusion to penetrate the host cell, while non-enveloped viruses use receptor-mediated endocytosis.

    Virus Cultivation

    • Animal viruses are cultivated in cell culture or in embryonated eggs.
    • Bacteriophages are cultivated in bacterial cultures.

    Virus Detection

    • Viruses are detected through various methods, including observation of cytopathic effects, hemagglutination, and PCR.
    • Plaques are areas of lysed bacteria on an agar plate, used to quantify bacteriophages.

    Bacteriophage Replication

    • A step that is not part of bacteriophage replication is binary fission.

    Retroviruses

    • A retrovirus is a type of virus that converts its RNA genome into DNA, which is then integrated into the host genome.

    Host Range

    • Host range refers to the range of species that a virus can infect.

    Viral Growth Curve

    • A viral growth curve is a graphical representation of the growth of a virus over time, showing the stages of eclipse, latent, and lytic phases.

    Other

    • Viroids are small, single-stranded RNA molecules that infect plants, lacking a protein coat.
    • Virusoids are small, single-stranded RNA molecules that are dependent on a helper virus for replication.

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    Description

    Test your knowledge on viruses and their characteristics with this informative quiz. Learn about the components of a virus, such as the protein coat, nucleic acid, and envelope. Explore the different forms of a capsid and understand the concept of host range. Discover the criteria for classifying viruses based on host organism, morphology, and genome type. Challenge yourself and expand your understanding of these fascinating microorganisms.

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