Microbiology 4

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Microbiology 4
2010-05-19 15:55:57

Microbiology: A human perspective - Chapter 4
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  1. How do procaryotic cells divide?
    • Binary Fission
    • Exponentially
  2. What is generation time?
    Time it takes for population to double
  3. What is a pure culture?
    Population of cells derived from a single cell - all genetically identical.
  4. How do you obtain a pure culture?
    Isolation of cells
  5. What is AGAR?
    Gelatinous medium derived from red-algae.
  6. What is the streak plate method?
    • Most common way of isolating bacteria.
    • Bacteria streaked on a plate in different directions
  7. What are the growth phases of bacteria?
    • Lag Phase - preparation for growth.
    • Log Phase - Period of exponential growth
    • Stationary Phase - Population growth remains stable; growth = death
    • Death Phase - Number of viable cells decrease at a constant rate.
    • Phase of Prolonged Decline - Very gradual decrease in population; may last days or years.
  8. What is a continuous culture?
    Bacterial growth can be maintained exponentially.
  9. What are the major conditions that influence bacterial growth?
    • Temperature
    • Oxygen
    • pH
    • Water Availability
  10. What 5 categories are procaryotes divided into?
    • Psychrophiles - freezing temps
    • Psychrotrophs - cold temps
    • Mesophiles - comfortable temperatures; disease causing
    • Thermophiles - hot springs
    • Hyperthermophiles - hydrothermal vents, volcanoes, usually archae
  11. What does aerobic and anaerobic mean?
    • aerobic - oxygen
    • anaerboic - no oxygen
  12. What is an obligate aerobe?
    Must have oxygen to grow.
  13. What is an obligate anaerobe?
    Can't have oxygen to grow
  14. What is a facultative anaerobe?
    Grows better with oxygen.
  15. What is a microaerophile?
    Must have very little oxygen to grow.
  16. What is an aerotolerant anaerobe?
    Indifferent to oxygen - can grow with or without
  17. What is a heterotroph?
    Human - uses organismal carbon as a nutirent source
  18. What is an autotroph?
    Plants - uses inorganic carbon
  19. What is a phototroph?
    Derives energy from sunlight.
  20. What is a chemotroph?
    Derives energy from chemical compounds
  21. What is a complex media?
    • Contains a variety of ingredients, with no exact formula.
    • Example: Nurtient broth, Blood agar, Chocolate agar
  22. What is Differential media?
    Allows you to distinguish between different organisms.
  23. What is selective media?
    Only allows one selected organisms to grow.
  24. What is a direct cell count?
    • A direct count of cells usually using a microscope
    • Doesn't distinguish between living and dead cells.
  25. What is a direct microscopic count?
    • Counted over a grid
    • Quickest manual method
    • Gives estimate
  26. What is a viable cell count?
    Used to count living cells
  27. What is a plate count?
    • Measures viable cells growing on solid culture
    • Based on assumption that one cell gives rise to one colony
    • Ideal to count between 30 and 300 colonies