Micro Exam 2: Class Notes

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Micro Exam 2: Class Notes
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2011-06-20 23:09:26
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Microbiology
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Exam 2
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  1. large nutrient molecule
    macro
  2. small nutrient molecule
    micro
  3. macroelements/macronutrients
    • required in relatively large amounts
    • N. CHOPS
  4. trace elements/micronutrients
    required in trace amounts, often adequately supplied in water

    Mn, Zn, Co, Mo, Ni, Cu
  5. diatoms need __________ for cell wall
    silicilic acid
  6. N CHOPS
    components of CHO, lipids, proteins, nucleic acids
  7. K+
    macronutrient necessary for enzyme activity
  8. Ca+2
    macronutrient/ heat resistance
  9. Mg+2
    cofactor for enzymes and complexes with ATP
  10. Iron
    cofactor for enzymes and electron-carrying proteins
  11. requirement for C,H,O
    • 1) autotrophs use CO2 as sole C source
    • 2) heterotrophs use preformed organic molecules as C source
    • 3) microbial survival
  12. energy source for phototrophs:
    light
  13. energy source for chemotrophs:
    from oxidation of organic or inorganic compounds
  14. electron source of lithotrophs:
    reduced inorganic compounds
  15. electron source of organotrophs:
    reduced organic compounds
  16. photolithotrophs
    obtain energy from light and therefore use inorganic electron donors only to fuel biosynthetic reactions
  17. photolithotrophic autotrophs
    • 1) use light energy and CO2 as C source
    • 2)Eucaryotic
  18. photoorganotrophic heterotrophs
    • 1) purple and green bacteria
    • 2) common inhabitants of polluted lakes and streams
    • 3) use organic matter, electron donor, and C source
  19. chemolithotrophic autotrophs
    • 1) oxidizes reduced inorganic compounds
    • ex) Fe, N, S molecules
    • 2)chemical transformation of elements
    • ex) NH4+ to NO3- (N-cycle)
  20. % N and O in atmosphere
    • O - 20%
    • N - 78%
  21. legume
    fix their own nitrogen
  22. TABLE 5.2
  23. mixotrophics
    • 1) demonstrate great metabolic flexibility
    • 2) Alter metabolic paths in response to environmental changes
    • 3) nonsulfur bacteria
  24. nonsulfur bacteria
    photoorganotrophic heterophytes under anaerobic conditions but oxidize organic molecules chemolithotrophically at normal O2 levels
  25. Requirements for Phosphorus:
    • 1) present in nucleic acids, phospholipids, nicleotides (ATP), and others
    • 2) direct OP uptake by transport proteins
    • 3) most use inorganic
  26. Requirements for Sulfur:
    • 1) needed in the synthesis of certain amino acids, eg; cystein and methionine
    • 2) meets requirements by assimimlatory sulfate reduction
  27. Passive Diffusion
    • 1) a phenomenon in which molecules move from an area of high concentration to an area of low concentration because of random thermal agitation
    • 2) requires a large concentration gradient for significant levels of uptake
    • 3) limited only to a few small molecules (eg. O2, H2O, CO2, glycerol)
  28. Facilitated Diffusion
    • 1) a process that involves a carrier molecule (permease) to increase the rate of diffusion
    • 2) net effect is limited to movement from an area of higher concentration to an area of lower concentration
    • a. requires smaller concentration gradient than passive diffusion
    • b. generally more important in eukaryotes
    • c. rate plateus when carrier becomes saturated
  29. Active Transport
    • 1) process in which metabolic energy is used to move molecules to the cell's interior where solute concentration is already higher (against concentration gradient)
    • 2) involves carrier proteins (permeases) with specificity for binding solutes transported
  30. Characteristics of active transport
    • a. saturable uptake rate (similar to facilitated diffusion)
    • b. requires expenditure of metabolic energy
    • c. concentrates molecules inside the cell even when the concentration inside is already higher
  31. ATP- binding cassette transport (ABC transporters)
    use ATP to drive transport against a concentration gradient
  32. Types of Active transport
    • 1. symport
    • 2. antiport
  33. symport
    • type of active transport: linked transport of 2 substances in the same direction (inward or outward)
    • e.g. E. Coli permease- transports lactose & proton inward
  34. antiport
    • type of active transport: linked transport of 3 substances in opposite directions
    • e.g.: E. Coli Na+ transport system pumps Na+ outwards in response to inward movement of protons
  35. Iron uptake:
    • a. Fe3+ and it's derivatives are extremely insoluable, little free iron available
    • b. sidererophores (low MW) complex with very insoluble ferric ion, which is the transported into the cell
    • c. secreted when little iron is available in medium
  36. catabolism
    the breakdown of larger, more complex molecules into smaller, simpler ones during which energy is release, trapped, & made available for work
  37. anabolism
    the synthesis of complex molecules from simpler ones during which energy is added as input
  38. chemical work
    synthesis of complex molecules
  39. transport work
    nutrient uptake, waste elimination, ion balance
  40. mechanical work
    internal & external movement
  41. photosynthesis
    • a. major source of biological energy
    • b. photoautotrophs and chemolithoautotrophs trap energy and use some to produce organic molecules from CO2
  42. orgnaic molecules serve as source of ___________.
    carbon
  43. calorie
    amount of heat energy needed to raise 1.0 gram of water from 14.5 to 15.5*C
  44. First Law of Thermodynamics
    energy can be neither created nor destroyed
  45. Second Law of Thermodynamics
    physical & chemical processes proceed in such a manner that disorder of the universe increases to the max. possible
  46. entropy
    disorder
  47. cell reactions are mostly ___________.
    endergonic
  48. endergonic
    positive stadard free energy
  49. removal of __________ by hydrolysis goes almost to completion - ___________
    terminal P

    strongly exergonic
  50. exergonic
    negative standard free energy
  51. ATP has high ________________ transfer potential.
    high phosphate group
  52. _______________ makes ATP well suited for it's tole in energy currency
    the high energy potential
  53. ATP is formed from _______________ by trapping processes.
    ADP + Pi
  54. enzymes
    protein catalysts with great specificity

    increases the rate of a reaction without being personally altered
  55. for any reaction to proceed to completion, it depends on ______________.
    rate limiting enzymes
  56. feedback inhibition
    the end product inhibits the pacemaker enzyme that catalyzes the slowest (rate-limiting) reaction
  57. The 3 Main Sources of Energy for M.O.'s
    fermentation, aerobic respiration, anaerobic respiration
  58. fermentation
    organic energy souce oxidized & degraded without the use of an exogenous electron acceptor
  59. FIGURE PG. 125
  60. Three major routes of breakdown of glucose to pyruvate:
    • 1) glycolysis
    • 2) pentose phosphate pathway
    • 3) Entner-Duodoroff pathway
  61. other name for glycolysis pathway
    Embden-Meyerhof pathway
  62. Glycolytic pathway
    • a) 6-Carbon sugar: glucose is phosphorylated twice --> fructose 1,6 bi-phosphate, using 2 ATPs
    • b) 3-Carbon sugar: fructose 1,6 biphosphate cleaves into two 3-C molecules, each processed to pyruvate
    • EACH 3-C YIELDS:
    • -2 ATPs (total of 4 ATPs; not gain of 2 ATPs per glucose)
    • - 1 NADH (2 NADHs per glucose)
  63. Pentose Phosphate Pathway
    • 1. produces a variety of 3-, 4-, 5-, 6-,& 7-C sugar PO4's
    • 2. converts 3 G-6-PO4 to 2 fructose-6-PO4 & a glyceraldehyde-3-PO4
    • 3. Produces NADPH- source of electrons for biosynthesis
    • 4. 4- & 5-C skeletons can be used for synthesis of macromolecules (amino-acids; nucleic acids)
  64. Entner-Duordoff (E-D) pathway
    • 1) most bacteria use the glycolytic and pentose pathways, but some substitute the E-D for glycolysis
    • 2) produces ATP, NADPH, and NADH
  65. FIGURE 15.2
  66. fermentation
    • 1. an energy-yielding process in which an energy substrate is oxidized without an exogenous electron acceptor
    • 2. regeneration of NAD+ used during oxidation of glyceraldehyde-3-PO4 to 1,3-biphosphoglycerate
  67. alcoholic fermentation produce ___________.
    ethanol & CO2
  68. Lactic acid fermentation produces ___________.
    Lactic acid (lactate)
  69. ________________ reduce pyruvate to lactate.
    homolactic fermentors
  70. _____________ for substatial smounts of products other than lactate.
    heterolactic fermentors
  71. Formic acid fermentation produces either ___________ or ____________.
    mixed acids or butane diol
  72. Tri-carboxylic (TCA) Acid cycle
    • 1. pyruvate can be degraded to CO2 by the TCA cycle after first being converted to acetyl-CoA
    • 2. The reaction is accomplished by loss of one carbon atom as CO2
    • 3. ATP is produced in substrate-level phosphorylation
    • 4. 3 molecules NADH & 1 of FADH are produced
  73. yield of ATP by glycolysis during fermentation
    2 ATP's
  74. aerobic respiration (# ATP's)
    (depending on precise nature of electron transport system) 2 to 38 ATP's
  75. microbial growth
    an increase in cellular constituents that may result in an increase in cell size, an increase in cell number, or both
  76. microbiologists follow changes in _____________.
    total population numbers
  77. LAG phase
    • 1. period of apparent inactivity during which the cells are adapting to a new environment and preparing for reproductive growth
    • 2. cell may be synthesizing new cell components
  78. Two factors how mucrobes function:
    • Biotic
    • Abiotic
  79. Biotic factors
    meaning of or related to life, are living factors. Plants, animals, fungi, protist and bacteria are all biotic or living factors
  80. Abiotic factors
    meaning not alive, are nonliving factors that affect living organisms. Environmental factors such habitat (pond, lake, ocean, desert, mountain) or weather such as temperature, cloud cover, rain, snow, hurricanes, etc. are abiotic factors.
  81. phase varies in length depending on ____________________.
    the condition and nature of the microorganisms and the culture medium
  82. LOG phase
    • 1. period during which the microorganisms are growing @ maximal rate possible given their genetic potential, nature of medium & conditions
    • 2. population is most uniform in terms of chemical & physical properties at this stage
    • 3. balanced growth
    • 4. microbe growth limited by low concentration of required nutrient
    • 5. Increase in yield results when the limiting nutrient is supplied- Law of Limiting Factor
    • 6. Growth rate increase with increasing nutrient concentration to point of diminishing returns
  83. stationary phase
    • 1. period in which number of viable microorganisms remains constant because:
    • a) metabolically active cells stopped reproducing
    • b) reproductive rate = death rate
  84. reasons for microbes to enter stationary phase:
    • a) nutrient limitation
    • b) toxic waste accumulation (alcohol 13%)
    • c) cell density (space)
  85. responses to starvation/low nutrient concentration have practical medical and industrial applications
    the responses may include changes in morphology, gene expression & physiology
  86. death phase
    • 1. cells irreversible loss of ability to reproduce
    • 2. period during which cells are dying at an exponential rate
  87. generation time
    time required to double population
  88. Influence of encironmental factors on growth
    • 1. ability to adapt to adverse conditions
    • 2. prokaryotes grow in harsh environmental conditions that kills most other organisms
  89. Major environmental factors:
    • temperature
    • radiation
    • o2 levels
    • pressure
    • pH
    • solutes and water activity
  90. Available H2O can be reduced by:
    • 1. interaction with solutes (osmotic effect)
    • 2. absorption to solids (matric effect)
  91. Aw
    the amount of water available to microorganisms

    Aw=Vp(solution)/Vp of pure water
  92. osmotolerant organisms
    can grow in solutions of both high and low Aw
  93. ______________ require environment of low Aw (high osmotic pressure due to salt concentration) to grow
    halophiles
  94. pH=
    pH=-log[H+]; log(1/[H+])
  95. acidophiles
    0-5.5
  96. neutrophiles
    5.5-8.0
  97. alkalophiles
    8.5 - 11.5
  98. extreme alkalophiles
    10 or higher

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