Microbiology: Bacteria and Viruses Quiz (BMS Learning Outcomes)
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Questions and Answers

What is a distinguishing feature of all viruses compared to bacteria?

  • Ability to reproduce independently
  • Encased in a protein shell called a capsid (correct)
  • Single circular DNA chromosome
  • Presence of membrane-bound organelles
  • Which type of virus is HIV classified as based on its nucleic acid?

  • Single-stranded DNA
  • Double-stranded RNA
  • Single-stranded RNA (correct)
  • Double-stranded DNA
  • Which of the following is NOT a feature of bacteria?

  • Presence of chlorophyll (correct)
  • Ancient life form
  • Lack of membrane-bound organelles
  • Single circular DNA chromosome
  • What type of symmetry does the influenza virus exhibit?

    <p>Filamentous or spherical (C)</p> Signup and view all the answers

    What is the primary tropism of the Hepatitis B virus?

    <p>Liver cells (D)</p> Signup and view all the answers

    Which virus is characterized by its ability to mutate more rapidly?

    <p>RNA viruses (B)</p> Signup and view all the answers

    Which of the following viruses causes cold sores?

    <p>Herpes Simplex Virus (HSV-1) (A)</p> Signup and view all the answers

    What is the classification of Varicella Zoster Virus based on its nucleic acid?

    <p>Double-stranded DNA (B)</p> Signup and view all the answers

    Which type of cell does HIV primarily target?

    <p>CD4+ T-cells (A)</p> Signup and view all the answers

    Which statement about gram-negative bacteria is true?

    <p>They are generally more resistant to antibiotics. (C)</p> Signup and view all the answers

    Which virus is primarily associated with the persistence of infections without killing host cells?

    <p>Human Immunodeficiency Virus (C)</p> Signup and view all the answers

    What best describes viral latency?

    <p>Dormant virus that can reactivate under certain conditions (C)</p> Signup and view all the answers

    What is the first step in the viral replication cycle?

    <p>Adsorption to host cell receptors (A)</p> Signup and view all the answers

    Which type of tropism is demonstrated by the Hepatitis B virus?

    <p>Tissue Tropism (D)</p> Signup and view all the answers

    What is a key feature that distinguishes prions from viruses?

    <p>Lack of nucleic acids (A)</p> Signup and view all the answers

    Which of the following infections could be caused by a prion?

    <p>Creutzfeldt-Jakob Disease (C)</p> Signup and view all the answers

    What process describes how new virions are released from an infected host cell?

    <p>Lysis or budding (D)</p> Signup and view all the answers

    What type of virus is commonly associated with oropharyngeal cancers?

    <p>Human Papillomavirus (D)</p> Signup and view all the answers

    Viral persistence is characterized by which of the following?

    <p>Silent periods without viral replication (B)</p> Signup and view all the answers

    What defines the mechanism of adsorption in viral replication?

    <p>Virus attaching to specific receptors (C)</p> Signup and view all the answers

    Flashcards

    Bacteria: Key features

    Single-celled organisms lacking chlorophyll, with a single circular DNA chromosome and no membrane-bound organelles.

    Gram staining

    A technique used to classify bacteria based on their cell wall structure, dividing them into Gram-positive and Gram-negative groups.

    Viral Capsid

    Protein shell that encases the viral genome, protecting and delivering the genetic material.

    Viral Genome

    The genetic material of a virus, which can be either DNA or RNA, but never both.

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    Viral Envelope

    An external lipid membrane that surrounds the capsid of some viruses, aiding in entry and evading the host's immune system.

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    Nucleocapsid

    Combination of the capsid and the viral genome.

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    Viral Symmetry

    A classification system for viruses based on the shape of their capsid, which can be icosahedral (spherical), filamentous, or complex.

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    Viral Nucleic Acid Classification

    Classifies viruses based on their genetic material, which can be DNA (double-stranded or single-stranded) or RNA (single-stranded or double-stranded).

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    HIV: Structure and Classification

    A single-stranded RNA retrovirus that targets immune cells (CD4+ T-cells), causing a weakening of the immune system.

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    Hepatitis B Virus: Structure and Classification

    A double-stranded DNA virus that infects liver cells (hepatocytes), leading to inflammation and potential liver damage.

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    Viral Tropism

    The ability of a virus to infect specific cells, tissues, or hosts.

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    Cellular Tropism

    Virus infects a specific type of cell (e.g., HIV infects CD4+ T-cells).

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    Tissue Tropism

    Virus shows a preference for a particular tissue (e.g., Hepatitis B infects liver tissue).

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    Host Tropism

    Some viruses infect specific species (e.g., Rabies virus affects mammals).

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    Viral Replication Cycle

    The process by which viruses replicate and spread within a host. It involves multiple steps, from attachment to release.

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    Viral Persistence

    Refers to a virus that remains in the body, often with periods of active replication and silent periods.

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    Viral Latency

    A type of viral persistence where the virus remains dormant within a host cell and only becomes active when triggered.

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    Prions

    Infectious agents composed of misfolded proteins that cause other normal proteins to misfold.

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    Prion Diseases

    Neurodegenerative diseases caused by prions.

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    Key Features of Prions

    A key feature of prions is that they lack nucleic acids (DNA and RNA) and are highly resistant to denaturation.

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    Study Notes

    Bacterial Features

    • Bacteria are single-celled microorganisms.
    • They are ancient life forms.
    • Basic cellular functions are similar to other living cells.
    • Lack chlorophyll.
    • Typically have a single, circular DNA chromosome within the cytoplasm.
    • Lack membrane-bound organelles.

    Gram Staining

    • Gram staining classifies bacteria into two groups: Gram-positive and Gram-negative.

    Viral Structure and Classification

    • Structure:

      • Capsid: Protein coat enclosing the viral genome.
      • Viral Genome: DNA or RNA (never both).
      • Envelope: Some viruses have a lipid membrane surrounding the capsid.
      • Nucleocapsid: Combined capsid and genome.
      • Other Viral Proteins: Involved in replication.
    • Classification:

      • Symmetry: Icosahedral, filamentous, or complex.
      • Nucleic Acid: DNA (dsDNA or ssDNA) or RNA (ssRNA or dsRNA). RNA viruses mutate more frequently.

    Specific Virus Features

    • HIV:

      • Symmetry: Icosahedral.
      • Nucleic Acid: ssRNA, retrovirus.
      • Tropism: Targets CD4+ T-cells.
    • Hepatitis B Virus (HBV):

      • Symmetry: Icosahedral.
      • Nucleic Acid: dsDNA.
      • Tropism: Infects liver cells.
    • Varicella Zoster Virus (VZV):

      • Symmetry: Icosahedral.
      • Nucleic Acid: dsDNA.
      • Tropism: Skin and nerve cells (chickenpox/shingles).
    • Herpes Simplex Virus (HSV):

      • Symmetry: Icosahedral.
      • Nucleic Acid: dsDNA.
      • Tropism: Skin, mucous membranes, nerve cells (cold sores/genital herpes).
    • Influenza Virus:

      • Symmetry: Filamentous or spherical.
      • Nucleic Acid: ssRNA.
      • Tropism: Respiratory tract cells.

    Dentally Relevant Viruses

    • Herpes Simplex Virus (HSV-1): Oral herpes (cold sores).
    • Varicella Zoster Virus (VZV): Chickenpox/shingles (can affect oral tissues).
    • HIV: Immunocompromised patients susceptible to oral infections (e.g., candidiasis, Kaposi's sarcoma).
    • Human Papillomavirus (HPV): Linked to oral cancers.
    • Hepatitis B Virus (HBV): Risk of transmission during dental procedures.

    Viral Tropism

    • Viral tropism: Ability to infect specific cells, tissues, or hosts.
    • Cellular tropism: Virus infects specific cell types.
    • Tissue tropism: Virus preference for particular tissues.
    • Host tropism: Viruses infecting specific species.

    Viral Replication

    • Adsorption: Virus attaches to host cell receptors.
    • Penetration: Virus enters host cell.
    • Uncoating/Eclipse Phase: Viral genome is released.
    • Transcription: Viral genome produces mRNA.
    • Synthesis of Components: Viral proteins and genomes produced.
    • Assembly: Viral components assemble into new virions.
    • Release: Virions released (lysis or budding).

    Viral Persistence and Latency

    • Viral Persistence: Virus presence without immune clearance. Can include productive phases.
    • Examples: HIV, Epstein-Barr virus, Hepatitis B virus.
    • Viral Latency: Dormant virus in host cells. Replication triggered by external factors (stress, immunity suppression).
    • Examples: Herpes Simplex Virus (HSV), Varicella-Zoster Virus (VZV).

    Prions

    • Prions: Infectious misfolded proteins causing other proteins to misfold.
    • Key Feature: Lack nucleic acids, resistant to denaturation.
    • Diseases: Neurodegenerative like Creutzfeldt-Jakob Disease (CJD) and Bovine Spongiform Encephalopathy (BSE).
    • Relevance: Fatal; difficult to sterilize against.

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    Description

    This quiz covers essential features of bacteria and viruses, including their structural characteristics and classification methods. It highlights the differences between Gram-positive and Gram-negative bacteria, as well as details about viral structures and notable examples like HIV. Test your knowledge on these fundamental microbiological concepts.

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