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Microbiology Chapter 4 Deck 1

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Terms in this set (50)

  • What is a psychrophile?
    A microbe with an optimum growth temperature ≤15°C.
  • What is a defined medium?
    A medium whose exact chemical composition is known.
  • What does a bactericidal agent do?
    Kills cells without causing lysis.
  • What is the lag phase?
    Cells adapt to new conditions before rapid division begins.
  • What is an acidophile?
    A microbe that grows best at pH below 5.5.
  • What does a microscopic cell count measure?
    Total cells present, both living and dead.
  • What is a biofilm?
    Cells in a polysaccharide matrix attached to a surface.
  • What is sterilization?
    Killing all microbial cells.
  • What is generation time?
    Time required for a microbial population to double.
  • What is a halophile?
    A microbe with a specific requirement for NaCl.
  • What are macronutrients?
    Nutrients required in large amounts.
  • What does UV radiation damage?
    DNA.
  • What is a batch culture?
    A closed-system microbial culture with a fixed volume.
  • What is a facultative aerobe?
    Grows with or without O₂ but grows better with O₂.
  • What is a complex medium?
    A medium containing digests of microbial, animal, or plant products.
  • What happens to cells in a hypertonic solution?
    Water flows out of the cells.
  • What are the four phases of batch growth?
    Lag, exponential, stationary, and decline/death.
  • What does an autoclave use to sterilize?
    Steam under pressure at high temperature.
  • What is a xerophile?
    A microbe able to grow in very dry environments.
  • What is the first step of binary fission?
    The DNA is copied.
  • What is a selective medium?
    A medium that inhibits some microbes but allows others to grow.
  • What is the optimum cardinal temperature?
    Temperature at which growth is fastest.
  • What are growth factors?
    Organic micronutrients, such as vitamins.
  • What is a bacteriostatic agent?
    An agent that inhibits bacterial growth.
  • What is planktonic growth?
    Growth of free-floating or free-swimming cells.
  • What is osmosis?
    Water movement from low to high solute concentration.
  • What is the purpose of a viable cell count?
    To measure living, reproducing cells.
  • What is a thermophile?
    A microbe with an optimum growth temperature of 45–80°C.
  • What happens during exponential phase?
    Cells double at regular intervals.
  • What does a differential medium contain?
    An indicator that detects metabolic reactions during growth.
  • What are CHNOPS?
    Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
  • What is pasteurization?
    Heat treatment that significantly reduces microbes in heat-sensitive liquids.
  • What is a microaerophile?
    A microbe requiring O₂ below atmospheric levels.
  • What is the minimum cardinal temperature?
    Lowest temperature at which a microbe can grow.
  • What is a colony-forming unit (CFU)?
    A unit used to report viable microbial counts.
  • What does catalase help eliminate?
    Toxic oxygen intermediates.
  • What is a chemostat?
    A continuous-culture device where fresh and spent media flow at equal rates.
  • What happens to cells in an isotonic solution?
    No net water movement occurs.
  • What is a sanitizer?
    A less-harsh agent that reduces microbial numbers without sterilizing.
  • What are micronutrients?
    Nutrients required in minute amounts.
  • What is cryptic growth?
    Cells reuse resources from dead cells to continue growth.
  • What is an obligate anaerobe?
    A microbe inhibited or killed by oxygen.
  • What does optical density estimate?
    Microbial cell numbers based on turbidity.
  • What is a hyperthermophile?
    A microbe with an optimum growth temperature above 80°C.
  • What is the purpose of compatible solutes?
    Maintain positive water balance during osmotic stress.
  • What is the stationary phase?
    Cell division equals cell death, so population growth is zero.
  • What is disinfection?
    Killing or severely inhibiting pathogens, but not necessarily all microbes.
  • What is the formula for generation time?
    g = t ÷ n, where g is generation time, t is time, and n is number of generations.
  • What is sessile growth?
    Growth of cells attached to a surface.
  • What is an antiseptic?
    An antimicrobial safe enough for use on living tissue.