Micro Ch 6 Microbial Growth

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  1. Increases in number of cells, not cell size
    population, colonies
  2. Binary fission:
    • -one cell becomes two
    • -parent cells enlarge
    • -duplicates it chromosomes
    • -starts to pull its cell envelope together to the center of the cell
    • -cell wall eventually forms a complete central septum
  3. Generation/doubling time
    the time required for a complete fission cycle; from parent cell to two daughter cells.
  4. what is average generation time?
    30-60 mins;most pathogens have relatively short generation times
  5. How are cell populations represented?
    Represented by the number with an exponent: 2^1, 2^2, 2^3, 2^4, etc. (after 2 generation get 4 populations total, after 3 generations get 8 populations total)
  6. Lag phase in the growth curve for bacteria
    No cell division is occurring, cells adapting to new environment
  7. Exponential (log) phase for growth curve of bacteria
    Cells are doubling the population every generation. Rapid growth, lots of nutrients and space
  8. Stationary phase in growth curve for bacteria
    Growth rate is equal to death rate. Environmental factors are limiting the population. Less space and nutrients
  9. Death phase in growth curve for bacteria
    Growth rate is less than death rate. Environmental factors are limiting the population. More dying than living cells, build up toxins from death
  10. Heterotroph
    An organism that must obtain its carbon in an organic form
  11. Autotroph
    An organism that uses inorganic CO2 as its carbon source

    Inorganic= can have carbon but not have hydrogen

    Organic= must have both carbon and hydrogen
  12. Phototroph
    Microbes that photosynthesize
  13. Chemotroph
    Microbes that gain energy from chemical compounds
  14. Diffusion:
    Transport mechanism, molecules move from an area of higher concentration to area of lower concentration
  15. Osmosis:
    Transport mechanism, the diffusion of water through a selectively or differentially permeable membrane
  16. Phagocytosis:
    Transport mechanism, endocytosis, accomplished by amoebas and white blood cells, ingest whole cells or large solid matter
  17. Pinocytosis:
    transport mechanism, endocytosis, ingestion of liquids such as oils or molecules in solution
  18. Chemical requirements for growth:
    • Carbon
    • Nitrogen, sulfur, and phosphorus
    • Trace elements¬†
    • Oxygen
    • Organic growth factor
  19. Carbon:
    Chemical requirement for growth, structural organic molecules, energy source
  20. Chemohetertrophs
    Use organic carbon sources
  21. Autotrophs
    use CO2
  22. Nitrogen:
    Chemical requirement for growth, in amino acids and proteins
  23. Most bacteria decompose ______
  24. In nitrogen bacteria use _______ or ________
    NH4+ or NO3-
  25. A few bacteria use N2 in
    Nitrogen fixation
  26. Sulfur:
    Chemical requirement for growth, in amino acids, thiamine, and biotin
  27. In sulfur bacteria uses _____ or ______
    SO4^2- or H2S
  28. Phosphorus
    Chemical requirement for growth, in DNA, RNA, ATP, and membranes
  29. Source of phosphorus
  30. Trace elements
    Chemical requirement for growth, inorganic elements required in small amounts usually as enzymes cofactors
  31. 3 types of temperature:
    • Minimum growth temperature
    • Optimum growth temperature
    • Maximum growth temperature
  32. Physical requirements:
    • Temperature
    • pH
    • Osmotic pressure
  33. Most bacteria grow between pH
    6.5 and 7.5
  34. Molds and yeast grow between pH
    5 and 6
  35. Acidophiles
    Grow in acidic environments
  36. Heliobacter pylori
    Barry Marshall discovered ulcers caused by bacteria, not lifestyle, diet, stress
  37. Osmotic pressure
    Isotonic environments are ideal, from water entering or leaving the cell because not isotonic environment
  38. Plasmolysis is caused by
    Hypertonic environments, or an increase in salt or sugar, water leaves the cell
  39. Require high osmotic pressure
    Extreme or obligate halophiles
  40. Tolerate high osmotic pressure
    Facultative halophiles
  41. Gases that influence microbial growth
    O2 and CO2
  42. Greatest impact on microbial growth
  43. Important respiratory gas and a powerful oxidizing agent
  44. Microbes fall into one of three categories:
    • -Those that use oxygen and detoxify it
    • -Those that can neither use oxygen nor detoxify it
    • -Those that do not use oxygen but can detoxify it
  45. Obligate aerobes
    Microbes grow on top
  46. Facultative anaerobes
    Microbes grow best in oxygen but can grow without if have to
  47. Obligate anaerobes
    Microbes that grow without oxygen
  48. Aerotolerant anaerobes
    Microbes do not use oxygen, detoxify it
  49. Microaerophiles
    Microbes can not grow with too much or too little of oxygen, just right amount of oxygen
  50. Symbiotic
    Organisms live in close nutritional relationship; required by one or both members
  51. Symbiotic relationship categories:
    • Mutualism
    • Commensalism
    • Parasitism
  52. Mutualism
    Obligatory dependent, both members benefit
  53. Commensalism
    The commensal benefits, other member not harmed
  54. Parasitism
    Parasite is dependent and benefits, host is harmed
  55. Biofilms
    Microbial communities, form of slime or hydrogels
  56. Bacteria attracted by chemicals via
    Quorum sensing
  57. Share nutrient and sheltered from harmful factors
  58. Counting bacteria: Direct methods
    • Serial dilutions
    • Plate counts
    • Membrane filtration
    • Direct Microscopic count
  59. Which method of counting bacteria is after incubation, count colonies on plates that have 25-250 colonies
    Plate Counts
  60. Membrane filtration
    Bacteria in water sieved out onto surface of a membrane filter. Individual bacteria grow into visible colonies
  61. Direct microscopic count
    Number of bacteria/ml= number of cells counted/volume of area counted
  62. Turbidity
    Indirect method, estimate how many cells in media
  63. Measure how many bacteria have by how cloudy media look
  64. Direct methods for measuring microbial growth
    • Plate Count
    • Filtration
    • Direct microscopic count
  65. Indirect method measuring microbial growth
    • Turbidity
    • Metabolic activity
    • Dry weight
  66. Metabolic activity
    Measure gas CO2 how many cells have
  67. Dry weight
    Use for fungi, before and after dry weight, see difference
Card Set:
Micro Ch 6 Microbial Growth
2015-02-03 02:42:29
10808 Micro

Unit 2 Chapters 6-10
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