Micros-Ch. 5.4-5.14

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blackitty42
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48089
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Micros-Ch. 5.4-5.14
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2010-11-08 02:44:42
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Microbiology
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Enzymes, Oxidation-Redox, Energy, Catabolism
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  1. Free Energy
    • (G): The energy released that is able to do work
    • Delta G 0' : change in free energy @ standard conditions
  2. Exergonic

    Endergonic
    • Exergonic - releasing free energy
    • ex- conserved ATP
    • Endergonic - requiring energy
  3. Calculating Delta G0
    • Delta G0' = Gf0 [C+D] - Gf0 [A+B]
    • product - reactant
  4. Delta G0' vs Delta G
    Delta G0' : standard conditions

    • Delta G : under various conditions
    • ( Delta G = Delta G0' + RT ln K )
  5. Activation Energy
    Energy required for a reacion to occur
  6. Catalyst
    • A substance that lowers the activation energy
    • --> increasing the rate of rxn
    • ex- enzymes
  7. Enzymes
    • Biological catalysts
    • made of protein
    • Enzyme binds to a substrate
    • @ the Activation site
    • Increase the rate of rxn by 108-20
  8. For enzymes to catalyze a specific rxn...
    • 1. bind to the substrate
    • 2. position the substrate
  9. Prosthetic group

    Coenzyme
    • small nonprotein molecules that aid in the catalysis.
    • Prosthetic Group - tightly bound to enzyme
    • ex- the heme group in Cytochrome

    • Coenzyme - loosely bound to enzyme
    • ex- derivative of niacin vitamin (NAD+/ NADH)
  10. Oxidation-Reduction rxn require e- donors & e- acceptors. The tendency of a compound to accept or release e- is expressed quantitatively by its reduction potential ( E0' ).
    • Energy is conserved in cells from Redox rxn
    • ex- ATP
  11. Oxidation vs Reduction
    • Oxidation - the removal of an e-: e- donor
    • ex- H2
    • Reduction = the addition of an e- : e- acceptor
    • ex- O2
  12. Half reaction
    for every substance that is oxidized, one must go through reduction.

    e- cant be by itself. so only half of the rxn can occur
  13. Reduction Potential
    • potential to accept or donate an e-.
    • The more (+) V --> the more able to accept
    • The more (-) V --> more donateable

    They are expressed in half rxn.
  14. Redox Couple
    ex: 2 H+ / H2 or 1/2O2 / H2O

    • H2 is more of a donor
    • O2 is more of an acceptor
  15. Redox Tower
    • listing of e- transfer rxn
    • strongest reductant on top: (-) e -donors
    • strongest oxidant on bottom: (+) e-acceptors
  16. The transfer of electrons from donor to acceptor in a cell typically involve electron carriers.
    Some electron carriers are membrane-bound, whereas others, such as NAD+ / NADH, are freely diffusible coenzymes
  17. Carriers
    intermediates between Redox rxn

    • Two types:
    • 1. Coenzyme - freely diffusible (ex-NAD, NADP)
    • 2. prosthetic group -tightly bound within cytoplasmic membrane
  18. Common diffusible carriers within a redox rxn
    • Freely diffusible carriers w/ 2e- and 2H+
    • 1.NAD + : (nicotinamide-adenine dinulceotide)

    2. NADP +: (NAD + phosphate)
  19. NAD/ NADH Cycling
    NAD+ can be reduced to NADH then give away e-, making it NAD+ again
  20. The erngy released in redox rxns is conserved in the formation of compounds that contatin energy-rich phosphate or sulfur bonds.
    The most common of these compounds is ATP, the prime energy carrier in the cell. Longer-term stroage of energy is linked to the formation of polymers, which can be consumed to yield ATP
  21. ATP
    Adenosine triphosphate

    ribonucleoside adenosime + 3 phosphate

    • release 32kJ of energy per breakdown
    • ATP --> ADP + Pi --> AMP
  22. Coenzyme A
    • energy-rich compounds
    • ex - Acetyl CoA
  23. Long term energy storage
    ATP is continuously broken down to drive anabolic rxn, and resynthesize at the expense of catabolc rxn.

    • Storage: insoluble polymers --> oxidized -->ATP
    • EX - glycogen, 'polys' , sulfur (prokaryotes)
    • starches and lipids (eukaryotes)
  24. Fermentation and respiration are two means by which chemoorganotrophs can conserve energy from the oxidation of organic compounds.
    During these catabolic rxns, ATP is synthesized by either substrate-lvl phosphorylation(fermentation) or oxidatiive phosphorylation (respiration).
  25. Substrate-lvl phosphorylation
    produces ATP in fermentation

    **Does NOT rely on proton motive force**
  26. oxidative phosphorylation
    produces ATP in respiration

    **rely on proton motive force**
  27. Photophosphorylation
    productionof ATP in phototrophs

    **rely on proton motive force**
  28. Glycolysis is a major pathway of fermentation and is widespread means of anaerobic metabolism.
    The end result of glycolysis is th release of a small amount of energy (2ATP) and production of fermented products.
  29. Embden-Meyerhof Pathway
    fermentation of glucose (Glycolysis)
  30. 3 stages of Glycolysis
    • 1. prepartory reaction
    • 2. the production of NADH, ATP, and pyruvate
    • 3. consumption of NADH and the production of fermented products
  31. Fermentation products
    • yeast: pyruvate is reduced by NADH to ethanol, production of CO2
    • Lactic acid bacteria: pyruvate reduced by NADH to lactate

    ALWAYS: NADH is reoxidized to NAD+
  32. Fermentation
    waste products

    distillers, the brewers, and the cheese makers
  33. Electron transport Systems consist of a series of membrane-associated electron carriers taht funtion in an integrated fashion to carry e- from the donor to the terminal acceptor.
  34. Aerobic Respiration
    Oxidation using O2 as the terminal electron accpetor. very high yield of ATP produced.
  35. Text book focus on Aerobic Respiration
    • 1. the way e- are transferred from organic compounds to the terminal e- acceptor
    • 2. the way organic carbon is converted to CO2
  36. Electron Transport Carrier Funtions
    • 1. mediates the transfer of e- from primary donor to terminal acceptors
    • 2. conserve some energy to later make ATP
  37. Types of oxidation-reduction enzymes as part of the ETS
    • NADH dehydrogenases
    • flavoproteins
    • iron-sulfur proteins
    • cytochromes
    • quinones
  38. NADH dehydrogenases
    protein bound inside the surface of the cytoplasmic membrane

    binds NADH --> NAD+ --> 2e- + 2H+ move on.
  39. Flavoproteins
    • the next carrier of the 2e & 2H
    • (keeps the 2H and passes on the 2e)

    • contains riboflavin
    • bound protein (prosthetic group)
    • FMN & FAD
  40. Cytochromes
    • proteins
    • contain heme prothetic groups
    • loses or gains e- through the Iron
    • different classes: a, b, c,
  41. Iron-sulfur proteins
    • clustesr of iron and sulfur atoms
    • ex- ferredoxin
    • reduction potential varies
    • carry electrons only
  42. Quinones
    • hydrophobic
    • non proteins
    • in bacteria, they are related Vitamin K
    • Accept 2 e- and 2 H+ but transfer only e-
  43. When e- are transported through an ETC, protons are extruded to the outside of the membrane forming the proton motive force.
    Key electron carriers include: flavins, quinones, cytochrome, etc (depends on the organism)

    **The cell uses the proton motive force to make ATP throught he activity of ATPsase
  44. Proton Motive Force
    • pH gradient and electrochemical potential
    • causing the membrane to be energized.-->ATP or just do work

    • inside the membrane more negative and alkaline
    • ouside the membrane more positive and acidic
  45. Electron Transport Rxn that lead to the formation of the proton motive force
    Complexes I & II
  46. ATPases
    • the complex that converst the proton motive force into ATP
    • consists of 2 components:
    • (1.) a multiprotein extramembrane complex called F1
    • (2) a proton-conducting intramembrane channel called F0
  47. Inhibitors and uncouplers
    • chemicals that affect the electron flow or the proton motive force.
    • inhibitors: CO ad CN stops ETC
    • uncoupling: lipid-soluble substances dinitrophenol and dicumarol - makes things leaky
  48. Reversiblity of the ATPase
    reason why fermetnative organisms dont have ETC and cant do oxidative phosphorylation

    instead function: generate the proton motive force
  49. Respiration results in the complete oxidation of an organic compound with much greater energy than occurs during fermentation.
    The citric acid cycle plays a major role in the respiration of organic compounds
  50. Respiration of Glucose
    glucose to pyruvate the same in glycolysis

    no fermentation but pyruvate is oxidized to CO2 (citric acid cyle)

    Pyruvate --> acetyl CoA-->kreb's cycle

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