Alcamo's Ch 5

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  1. Organisms that live in extreme environments are known as ____.
  2. Most bacterial organisms reproduce by an asexual process called ___ ___.
    Binary Fission
  3. ___ ___ at the midcell involves the synthesis of a partition or septum that separates the mother cell into 2 genetically identical daughter cells.
    Cell fission
  4. ___ ___ is a process to maintain genetic constancy while increasing cell numbers.
    Asexual reproduction
  5. The interval of time between successive binary fissions when a population doubles is known as what?
    Generation time
  6. Generation times vary. For example it in about 30 mins for ___ ___ but 15hrs for ___ ___.
    • Staphylococcus aureus
    • Mycobacterium Tuberculosis
  7. Why is knowing generation time useful?
    In order to help determine at what point symptoms may appear
  8. The time period fr when a pathogen enters the body to when symptoms first appear is known as ___ ___.
    Incubation period
  9. In preparation for fission, cells do what 3 things?
    • Grow in size
    • Store nutrients
    • Synthesis nutrients
  10. What does a bacterial growth curve illustrate?
    Events occurring over time
  11. What are the 4 distinct phases of the bacterial growth curve?
    • Lag phase
    • Log phase
    • Stationary phase
    • Decline phase
  12. During the lag phase of the bacterial growth phase what happens?
    Cells are adapting to their new environment and no cell divisions occur
  13. The length of the lag phase is dependent upon what?
    Metabolic activity in the cells
  14. What phase of the bacterial growth curve is characterized by exponential growth and binary fission?
    Log phase
  15. Why is it that disease symptoms develop during the log phase?
    B/c the cells cause tissue damage during this phase
  16. During what phase of the bacterial growth curve are bacteria most vulnerable to antibiotics and why?
    The log phase b/c many antibiotics affect metabolizing cells
  17. During the ____ phase population plateaus & reproductive and death rates equalize.
  18. What are 2 factors that lead to cell death during the stationary phase?
    • Limitation of nutrients
    • Build up of waste material
  19. What are 2 factors that contribute to the decline phase?
    • Limited nutrients in the external environment
    • Nutrient levels become exceedingly low
  20. During the ____ phase cells death far exceeds cell reproduction.
    Decline phase
  21. What are 2 things that could keep bacteria alive during the decline phase?
    • Presence of a glycocalyx
    • Flagella enabling the cell to move about
  22. ____ are dormant structures that can endure times of nutrient stress.
  23. Describe endospores. Gram status, genus.
    Gram-positive Bacillus & Clostridium living in soil
  24. When cells are said to be vegetative they are what?
    Actively metabolizing and obtaining nutrients
  25. When Bacillus & Clostridium experience limited carbon or nitrogen, reach critical mass & enter stationary phase what happens?
    They begin sporulation
  26. Sporulation begins when the bacterial ____ replicates & binary fission is characterized by ___ ___ ___.
    • Chromosome
    • Asymmetric cell division
  27. Explain what happens to a cell during sporulation.
    The smaller cell (prespore) becomes mature endospore & mother cells commits itself to maturation of endospore then lyses
  28. What substances are contained in a perspire cell?
    • Cytoplasm
    • DNA
    • Dipicolinic Acid
  29. A unique organic substance that helps stabilize proteins & DNA in spores is called what?
    Diplicolinic Acid
  30. What does an endospore represent in regards to a bacteria species?
    A dormant stage in life
  31. What happens to an endospore when it comes into a favorable environment for growth?
    The protective layers break down & it germinates into a vegetative state
  32. Botulism, gas gangrene & tetanus are diseases cause by different species of ____.
  33. Where are Clostridium found?
    Soil & human and animal intestines
  34. What is one way to kill endospores?
    High heat combined with high pressure
  35. What are 3 grps of temp oriented microbes?
    • Psychrophiles
    • Mesophiles
    • Thermophiles
  36. Microbes that have their optimal growth rates below 15⁰C but can still grow at 0⁰C - 20⁰C are called ___.
  37. Psychrotrophs & psychrotolerant microorganisms, w/their higher minimal & maximal growth temps are commonly found where?
    In spoiled refrigerated foods around 4⁰C
  38. Which temp oriented organisms grow best at temps around 60⁰C?
  39. Thermophiles are present in compost heaps & hot springs & an issue w/Pasteurization b/c . . . .
    They can survive pasteurization temperatures
  40. What 3 things make thermophiles stable at high temps?
    • Highly saturated fatty acids in cell membranes
    • Heat stabilizing proteins & enzymes
  41. ____ are archaeal species that grow optimally at temps exceeding 80⁰C.
  42. Which bacterial species survive best in the middle temp range 10⁰C to 45⁰C?
  43. Obligate aerobes must use ____ as the final e⁻ acceptor to make cellular energy.
  44. Microaerophiles survive in environments where . . . . .
    The concentration of oxygen is relatively low
  45. Anaerobes are microbes that cannot or do not use ____ at all.
  46. What effect does oxygen have on aerotolerant microbes?
    They are insensitive to oxygen
  47. Obligate anaerobes are ___ or ___ if oxygen is present.
    Inhibited or killed
  48. Clostridium that carry tetanus & gas gangrene multiply where and produce what?
    • In dead wound tissue
    • Toxins causing further damage
  49. Microbes that are neither aerobic nor anaerobic & can grow in either the presence of or a reduced concentration of oxygen are termed ____ organisms.
  50. A facultative aerobe prefers ____ conditions but can also grow ____.
    • Anaerobic
    • Aerobically
  51. A facultative anaerobe prefers ___-___ conditions but can also grow ____.
    • Oxygen-rich
    • Anaerobically
  52. Why do we use thioglycollate broth to test an organisms oxygen sensitivity?
    B/c it binds to free oxygen so that only fresh oxygen entering at the top of the tube would be available
  53. The cytoplasm of most organisms has a pH near ___.
  54. Acid-tolerant bacteria are called ____ & are valuable in the ___ & ___ industries.
    • Acidophiles
    • Food & Dairy
  55. What is hydrostatic pressure?
    Pressure exerted by water
  56. ____ live in high pressure areas.
  57. Microbes, like E. coli, that are unable to grow in the presence of salt are known as ____.
  58. Salt loving microorganisms are known as ___.
  59. ___ ___ represent a grp of archaea that tolerate salt concentration of 15% - 30%
    Extreme halophiles
  60. Aggregates of molecules in a finely divided state dispersed in a solid medium is called ___.
  61. What is a polysaccharide derived fr marine red algae & contains no essential nutrients used for growing colonies?
  62. A chemically undefined medium that contains nutrients in which the exact components or their quantity is not exactly known is called what?
    Complex medium
  63. Why are complex mediums often used in teaching?
    B/s we're not concerned about nutrients as long as the cultures grow
  64. What is the name given to a medium where the precise chem composition & amt of all components are known?
    Synthetic medium
  65. When might a synthetic medium be utilized?
    When we are trying to determine specific growth requirements
  66. A ___ ___ contains ingredients to inhibit the growth of certain microbes while allowing the growth of others.
    Selective medium
  67. A ___ ___ is a basic growth medium w/addition of 1 or more compounds that allows one to differentiate between very similar species based on biochemical or physiological properties.
    Differential medium
  68. If an organism is fastidious that organism has what?
    Complex nutritional requirements
  69. An enriched medium contains ___ ___.
    Special nutrients
  70. If a bacteria is viable but non-culturable (VBNC) it is what?
    This organism can not be grown in the lab
  71. How can we ID VBNC organisms?
    • Direct microscopic exam
    • Amplification of diagnostic gene sequences
    • 165 rRNA sequences
  72. The process of transferring bacteria fr 1 tube or plate to another is known as what?
  73. A pure culture is what?
    Population consisting of only 1 species
  74. What are direct methods for measuring microbial growth?
    • Direct microscopic count
    • Most probable number test
    • Std plate count procedure
  75. Explain direct microscopic counting.
    Using a specially designed counting chamber, count all cells
  76. What is a downfall to direct microscopic counting?
    It counts both live & dead cells
  77. Explain the most probable number test for counting cell growth.
    Samples added to lactose broth tubes & presence or absence of gas formed in fermentation gives rough statistical estimation of cell number
  78. Explain std plate count procedure.
    Samples of broth culture spread on agar plates using pour plate technique. Assume that each cell will divide numerous times to produce separate colonies. Count expressed in colony-forming units
  79. What is a colony-forming unit (CFUs)?
    A figure used to estimate number of viable cells originally plated
  80. What are 3 indirect methods of estimating cell numbers?
    • Measuring dry weight
    • Oxygen uptake in metabolism
    • Spectrophotometry
  81. Which of the following is NOT an event of sporulation (A. symmetrical cell division B. mother cell disintegration C. DNA replication D. Prespore engulfment by mother cell)?
    A. Symmetrical cell division
  82. If the carbon source in a growth medium is beef extract, the medium, the medium must be an example of a/an ___medium.
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Alcamo's Ch 5
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