Micro-organisms (L2)

Cards (17)

  • Impact of Micro-organisms

    • Causes disease
    • Uses in agriculture
    • Impact on the food industry
    • Can affect the environment
    • Uses in pharmaceutical industry
  • Koch's postulates

    A set of principles used to establish a causal relationship between a microorganism and a disease
  • Eubacter
    • Human pathogens
    • Clinical or environmental
    • One kingdom
  • Prokaryotes

    • Not compartmentalized
    • Cell membranes lack sterols (e.g. cholesterol)
    • Single circular chromosome
    • Ribosomal are 70S - subunits 30S (16S rRNA) and 50S (5S & 23S rRNA)
  • Bacterial cell structure: plasmids, cell envelope, flagella, pili (fimbriae), wall-less forms of bacteria, capsules and slime layers, endospores
  • Gram stain: Gram negative or gram positive
  • Flagella

    • Some bacteria are motile
    • Locomotory organelles
    • Taste environment
    • Respond to food/poison
    • Move propeller-like action
  • Pili (fimbriae)

    • Hair-like projections of the cell
    • Sexual conjugation
    • Adhesion to host epithelium
  • Wall-less forms of bacteria
    • Result from action of enzymes lytic for cell wall or antibiotics inhibiting peptidoglycan biosynthesis
    • Usually non-viable
  • Capsules and slime layers
    • Outside cell envelope
    • Usually polysaccharide
    • Often lost during in vitro culture
    • Protective in vivo
  • Endospores

    • Dormant cell
    • Produced when starved
    • Resistant to adverse conditions
  • Archaea
    • Environmental organisms
    • Second kingdom
  • Gram negative:
    • major permeability barrier
    • periplasmic space (where degenerative enzymes are stored)
    • Braun lipoprotein attaches peptidoglycan layer to the outer membrane
    • contains endotoxins (lipopolysaccharides that make up the outer part of the outer membrane)
    • more resistant to penecillin
  • Gram positive
    • no periplasmic space (degenerative enzymes are released externally)
    • lipoteichoic acid anchored the thick peptidoglycan cell wall to the membrane)
    • more susceptible to antibiotics and lysozyme than gram negative
  • What is peotidoglycan made out of?
    N-acetylglucosamine and N-acetylmuramic acid
  • Wall-less bacteria that don't replicate
    • Spheroplasts (with outer membrane)
    • Protoplasts (no outer membrane)
  • Wall-less bacteria that replicate
    • L forms