Micro Exam 2: Notes

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Micro Exam 2: Notes
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2011-06-21 14:33:09
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Exam 2
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  1. large nutrient molecule
    macro
  2. small nutrient molecule
    micro
  3. N. CHOPS
    required in relatively large amounts

    components of CHO, lipids, proteins, nucleic acids
  4. trace elements/ micronutrients
    required in trace amounts, often adequately supplied in water
  5. diatoms need for cell wall
    silicilic acid
  6. K+
    enzyme activity
  7. Ca2+
    heat resistance
  8. Mg2+
    cofactor for enzymes and complexes with ATP
  9. Iron (Fe+2, Fe+3)
    cofactor for enzymes and electron-carrying proteins
  10. source of carbon for autotrophs
    CO2
  11. carbon source for heterotrophs
    preformed organic molecules
  12. essential for microbe survival
    • 1. energy source
    • 2. process of breaking down and using energy (electron source)
  13. energy:
    phototrophs
    chemotrophs
    • use light as their energy source
    • from oxidation of organic and inorganic compounds
  14. electrons:
    lithotrophs
    organotrophs
    • -use reduced inorganic compounds as electron source
    • -use reduced organic compounds as electron source
  15. photolithotrophic aurotrophs
    • a. use light energy and CO2 as carbon source
    • b. eucaryotic
  16. Photoorganotrophic heterotrophs
    • a. purple-green bacteria
    • b. common inhabitants of polluted lakes and streams
    • c. use organic matter as electron donor and carbon source
  17. chemolithotrophic autotrophs
    • a. oxidizes reduced inotganic compounds; eg. Fe, N, S molecules
    • b. chemical transformation of elements; eg. NH4+to NO3- (N-cycle)
  18. percent oxygen in the atmosphere
    • O - 20%
    • N - 78%
  19. legume
    fix their own nitrogen (root microbes)
  20. TABLE 5.2
  21. mixotrophics
    • 1. demonstrate great metabolic flexibility
    • 2. Alter metabolic paths in response to environmental changes
    • 3. nonsulfur bacteria
  22. nonsulfur bacteria
    photoorganotrophic heterophytes under anaerobic conditions, but oxidize organic molecules and function chemolithotrophically at normal O2 levels
  23. Phosphorus
    • a. present in nucleic acids, phospholipids, nucleotides (ATP) and others
    • b. direct OP uptake by transport proteins
    • c. most use inorganic
  24. Sulfur
    • 1. needed in the synthsis of certain amino acids
    • eg. cysteine & methionine
    • 2. meets requirements by assimilatory sulfate reduction
  25. Passive diffusion
    • a. a phenomenon inn which molecules move from an area of high concentration to an area of low concentration because of random thermal agitation
    • b. requires a large concentration gradient for significant levels of uptake
    • c. limited only to a few small molecules (eg.: O2, H2O, CO2, glycerol)
  26. Facilitated diffusion
    • a. a process that involves a carrier molecule (permease) to increase the rate of diffusion
    • b. net effect is limited to movement from an area of higher concentration to an area of lower concentration
    • - requires smaller concentration gradient than passive diffusion
    • - generally more important in eucaryotes
    • - rate plateus when carrier becomes saturated
  27. 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 con. gradient)
    • 2. incolces carrier proteins (permeases) with specificity for binding solutes transported
  28. characteristics of active transport
    • a. saturable uptake rate (similar to facilitated diffusion)
    • b. requires expenditure as metabolic energy
    • c. concentrates molecules inside the cell even when the concentration inside is already higher
  29. _______________ use ATP to drive transport against a concentration gradient
    ATP-binding cassette transport (ABC transporters)
  30. symport
    • type of active transport- linked transport of two substances in the same direction (inward or outward)
    • eg. E. Coli permease- transports lactose & a proton inward
  31. antiport
    • a. linked transport of two substances in opposite directions
    • eg. E. Coli Na+ transport system pumps Na+ outwards in response to inward movement of protons
  32. Iron Uptake
    • a. Fe 3+ and its derivatices are extremely insoluable, little free iron available
    • b. Sidererophores (low MW) complex with very insoluble ferric ion, which is then transported into the cell
    • c. secreted when little iron is available in medium
  33. catabolism
    the breakdown of larger, more complex molecules into smaller, simpler ones during which energy is released, reapped, and made available for work
  34. anabolism
    the synthesis of complex molecules from simpler ones during which energy is added as input
  35. Types of work:
    chemical work, transport work, nutrient work
  36. chemical work
    synthesis of complex molecules
  37. transport work
    nutrient uptake, waste elimination, ion balance
  38. mechanical work
    internal and external movement
  39. Photosynthesis
    • a. major source of biological energy
    • b. photoautotrophs and chemolithoautotrophs trap energy
    • c. use some to produce organic molecules from CO2
  40. First Law of Thermodynamics
    • a. total energy in the universe remains constant
    • b. energy may be redustributed either within a system or between the system and its surroundings
    • c. energy is measured in calories
  41. calorie
    the amount of heat energy needed to raise 1.0 gram of water from 14.5 to 15.5*C
  42. Second Law of Thermodynamics
    physical and chemical processes proceed in such a manner that disorder of the universe increases to the max possible
  43. entropy
    disorder
  44. reactions are mostly _____________.
    endergonic
  45. endergonic
    positive standard free energy
  46. ATP has high _______________.
    phosphate group transfer potential
  47. ATP is formed from _________ by energy trapping processes.
    ADP + Pi
  48. enzyme
    • protein catalysts with great specificity
    • a. a caralyst is a substance that increases the rate of a reaction without being permanently altered
  49. acidophile
    0- 5.5
  50. neutrophiles
    5.5- 8.0
  51. alkalophiles
    8.5- 11.5
  52. extreme alkalophiles
    10 or higher
  53. pH
    pH=-log [H+] = log (1/[H+])
  54. feedback inhibition
    the end product inhibits the pacemaker enzyme
  55. The 3 Main Sources of Energy for microorganisms
    • 1. fermentation
    • 2. aerobic respiration
    • 3. anaerobic respiration
  56. fermentation
    organic energy source oxidized and degraded without the use of an exogenous electron acceptor

    electron acceptor: endogenous organic electron acceptor
  57. aerobic respiration
    O2 as the final electron acceptor
  58. anaerobic respiration
    • molecule other than O2 as the final electron acceptor
    • electron acceptor: NO3-, SO42-, CO2, fumerate
  59. Chemolithotrophy
    Inroganic electron donor

    O2, SO42-, NO3-
  60. FIGURE PG 125
  61. Three major routes of breakdown of glucose to pyruvate
    • - glycolysis
    • - pentose phosphate pathway
    • - Entner-Duodoroff pathway
  62. glycolytic pathway
    • (Embden-meyerhof pathway)
    • For each 3C produce 2 ATP
    • 1. 6-C sugar; glucose is phosphorylated twice ---> fructose 1,6-biphosphate using 2 ATPs
    • 2. 3-C 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, net gain of 2 ATPs per glucose)
  63. Pentose Phosphate Pathway
    • 1. produces a cariety of 3-, 4-, 5-, 6-, & 7-C sugar PO43
    • 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- skeletons can be used for synthesis of macromolecules (amino acids; nucleic acids)
  64. Entner- Douordoff (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 produces _______________.
    ethanol and CO2
  68. Lactic acid fermentation
    • a) homolactic fermentors reduce pyruvate to lactate
    • b) heterolactic fermentors form sustantial amounts of products other than lactate
  69. formic acid fermentation
    produces either mixed or butane diol
  70. Tri-carboxylic Acid (TCA) 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 of NADH and 1 of FADH2 are produced
  71. yield of ATP by glycolysis during fermentation
    2 ATPs
  72. Aerobic respiration (depending on precise nature of electron transport system)
    2 to 38 ATPs
  73. Mean generation time
    time required to double population
  74. Influence of Environmental Factors of Growth
    • 1. ability to adapt to adverse conditions
    • 2. procaryotes present where life can exist
    • a. extremophiles grow in harsh environmental conditions that kills most othe organisms
  75. Major Environmental Factors
    • 1. solutes and water activity
    • 2. pH
    • 3. temperature
    • 4. O2 levels
    • 5. pressure
    • 6. radiation
  76. Microbial growth
    an increase in cellular constituents that may result in an increase in cell size, an increase in cell number, or both

    Microbiologists forllow 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. cells may be synthesizing new cell components
  78. biotic factors
    meaning of or related to life, are living factors. Plants, animals, fungi, protist and bacteria are all biotic or living factors
  79. 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
  80. LOG phase
    • 1. period during which the m.o.s are growing @ maximal rate possible given their genetic potential, nature of medium & conditions
    • 2. population is most uniform in terms of chemical and physical properties @ this stage
    • 3. balanced growth
    • 4. microbe growth limited by low concentration of required nutrient
    • 5. increase in yield results when the limiting nutrients is supplied - Law of Limiting Factor
    • 6. growth rate increase with increasing nutrient concentration to point of diminishing returns
  81. stationary phase
    • 1. period in which number of viable microorganisms remains constant either because,
    • a. metabolically active cells stopped reproducing
    • b. reproductive rate = death rate
  82. reasons why microbes enter stationary phase
    • a. nutrient limitation
    • b. toxic waste accumulation (alcohol=13%
    • c. cell density (space)
  83. death phase
    • 1. cells irreversible loss of ability to reproduce
    • 2. period during which cells are dying at an exponential rate
    • 3. available H2O can be reduced by:
    • -osmotic effect
    • -matric effect
  84. osmotic effect
    interaction with solutes
  85. matric effect
    absorption to solids
  86. Aw
    amount of water available to microorganisms

    Aw= Vp(solution)/ Vp of pure water
  87. osmotolerant organisms
    can grow in solutions of both high and low Aw
  88. halophiles require ____________ to grow
    enviroment of low Aw (high osmotic pressure, due to salt concentration)

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