MICB Lecture 5

Cards (17)

  • Family, molecular, how long
    circular, single stranded RNA molecule
    family: pospiviroidae (replicate in nucleus)
    250-430 nucleotides long
  • Which is which
    PrPsc differs from PrPc in its 3 dimensional conformation, it is stable and aggregates with other PrPsc
    A) PrPc
    B) PrPsc
  • eukaryotic microbes exhibit both sexual and asexual reproduction
  • Prokaryotic microbes reproduce asexually through binary fission
  • FtsZ
    a key bacterial cytoskeletal protein in bacteria and archaea
  • FtsZ features
    Homologue of eukaryotic protein tubulin
    required for cell division and septum formation
    forms contractile ring at midcell
    energy from hydrolysis of GTP
  • batch culture
    closed vessel (test tube or flask), single batch of medium, population growth can be observed when microbes are cultivated in this
  • What is this
    Bacterial growth curve
    A) lag phase
    B) exponential phase
    C) stationary phase
    D) death phase
  • lag phase
    period following intro of microorganisms into fresh culture
    • no growth - cells synthesizing new components
    • can differ
  • exponential phase
    balanced, constant growth
    2, 4, 8, 16, 32
    growth expressed as generation (doubling time): time required for cells to divide
  • stationary phase
    Population growth ceases due to
    • carrier capacity
    • lack of oxygen
    • toxic biproducts
  • Death phase
    nutrient deprivation and buildup of toxic wastes cause irreparable harm to cells
  • Spores
    stress resistant, dormant cells
    forms when mother cell lysis
    A) bacillus
  • Name/disease
    Clostridium tetani
    causes tetanus, spores form at one pole
  • direct cell counts
    measures microbial growth
    Petroff-Hausser method of counting chambers
    drawback: overestimate cell count
  • Viable cell counts - measuring microbial growth
    Plating - colony forming units, combine with turbidity measurements
  • turbidity measurements - measuring microbial growth
    microbial cells scatter when light strikes them
    more turbid = more cells = more light scattered = higher absorbance reading on spectrophotometer