Host Invasion by Microorganisms Flashcards


Host invasion

Question Answer Article
By what three routes can pathogens enter the body?
  • Contact
  • Aerosol
  • Orofecal
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Viruses

Question Answer Article
Naked viruses contain only...?
  • RNA/DNA and protein coat
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Name three functions of viral structural proteins
  • Protection of the genome
  • Attachment to host cell
  • Fusion of envelope to host cell membrane
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Name the two main innate defences against viral infection
  • Interferon
  • Natural killer cells
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Upon viral infection, which antibody isotype is increased at mucosal surfaces?
  • IgA
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What do antibodies stop free virus particles from doing?
  • Binding to host cell, entering and uncoating
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By what mechanism is complement able to damage the virion envelope?
  • Virolysis
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When coupled with antibodies, what mechanisms does complement aid in immune defence?
  • Blocking the virus receptor
  • Lysis of infected cells
  • Opsonisation of free particles or infected cells
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What are the main cytokines CD4+ T cells release to recruit macrophages?
  • IFN-γ
  • TNF
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Bacteria

Question Answer Article
Describe three ways prokaryotic DNA differs from eukaryotic DNA
  • Few repeated sequences
  • Most of the DNA is transcibed
  • No intervening sequences within structural genes
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These surface components allow bacteria to move around
  • Flagella
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Bacteria with an outer layer of lipopolysaccharide are classed as...
  • Gram-negative
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Bacteria with a round shape are classed as...
  • Cocci
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Bacteria with a long shape are classed as...
  • Rods or bacilli
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What are the four rules summarising the cause and effect relationship between bacteria and infection?
  • Koch's postulates
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What is the condition, characterised by excessive cytokine production, that is caused by bacterial components such as LPS?
  • Endotoxin shock
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By what mechanism do most bacteria replicate?
  • Binary fission
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By what three mechanisms can bacteria transfer DNA?
  • Transformation
  • Transduction
  • Conjugation
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Parasites

Question Answer Article
Do protozoa have a eukaryotic or prokaryotic cell structure
  • Eukaryotic
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What are the two main groups of helminth parasite?
  • Nematodes
  • Platyhelminthes
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What is the main cell type that mediates the destruction of larger parasites?
  • Eosinophils
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What T cell subtype is required to fight intracellular protozoa
  • Th1
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What T cell subtype is required to fight intestinal worms?
  • Th2
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How do antibodies defend against parasitic infection?
  • Directly damaging protozoa
  • Activating complement
  • Blocking attachment to host cells
  • Enhancing macrophage phagocytosis
  • Antibody-dependent cell-mediated cytotoxicity
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