Bio Exam 4

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Bio Exam 4
2010-11-18 11:53:10
Energy Metobolism

Exam Review
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  1. Energy
    • Capacity to do work
    • can take many forms
    • -mechanical, heat, electric current, light
  2. Kinetic Energy
    The energy of motion
  3. potential Energy
    • stored energy
    • -energy thats stored in chemical bonds & can be transferred from one molecule to another by way of electrons
  4. Kilocalories and calories
    • what heat energy is measured in
    • Heat energy is what most forms of energy can be converted to
    • 1 kilocalorie (kcal)= 1000 calories

    calorie-amount of heat required to raise temp of water by 1 deg. C.
  5. Oxidation

    loss of electrons
  6. Reduction

    gain of electrons
  7. Redox reactions
    coupled to each other
  8. First Law of Thermodynamics
    • energy cant be created or destroyed
    • -can only be converted from one form to another
    • ex. sunlight energy --> chemical energy (by photosynthesis)
  9. Second Law of Thermodynamics & Entropy
    • disorder is more likely than order
    • -entropy is always increasing
    • -the more order, the more potential energy
    • ENTROPY-disorder in universal
    • potential=mechanical
    • entropy=disorder
  10. Free Energy & Enthalpy
    • energy available to do work
    • -denoted by symbol G (Gibbs free energy)
    • Enthalpy-energy contained in a molecule's chemical bonds
    • ""=stored away - (entropy x temp.)
    • free energy = enthalpy - (entropy x temp.)
    • G= H-TS
  11. When products contain more free energy than reactants...
    -^G (triangle) is positive
  12. when reactants contain more freee energy than products...
    -^G is negative
  13. Activation Energy
    • extra energy needed to get a reaction started
    • -destabilizes existing chemical bonds
  14. Catalysts
    substances that lower the activation energy of a reation
  15. ATP
    • adenosine triphosphate
    • the energy currency of cells
    • ATP structure:
    • -ribose, a 5-carbon sugar
    • -adenine
    • -3 phosphates
    • it stores energy in the bonds between phosphates
  16. ADP and Pi
    • when bond btwn phosphates is broken:
    • ATP-->ADP + Pi (energy is released)

    • ADP- adenosine diphosphate
    • Pi- inorganic phosphate
    • (this reaction is reversible)
  17. Enzymes
    • molecules that catalyze reactions in living cells
    • -most are protiens
    • -lower the activation energy required for a reaction
    • -not changed or consumed by the reaction
    • -interact with substrates
  18. Substrate
    • molecule that will undergo a reaction
    • *binding of an enzyme to a substrate causes the enzyme to change shape, producing a better induced fit btwn the molecules
  19. Active site
    region of the enzyme that binds to the substrate
  20. What affects an enzyme
    • enzyme function affected by its environment
    • -factors that can change an enzymes 3D shape can change its function they are:
    • pH- enzyme prefer 6-8
    • temp- temp. increase, so does reaction. too far above opt. temp can denature enzyme
    • regulatory molecules-
  21. Inhibitors
    molecules that bind to an enzyme to decrease enzyme activity
  22. Competitive inhibitors
    compete with the substrate for binding to the same active site
  23. noncompetitive inhibitors
    bind to sites other than the enzyme's active site
  24. Metabolism
    all chemical reactions occuring in an organism
  25. Anabolism
    chemical reactions that expend energy to make new chemical bonds
  26. Catabolism
    chemical reactions that harvest energy when bonds are broken
  27. cofactors
    • usually metal ions found in the active site participating in catalysis.
    • -helps in proper enzymatic activity
  28. coenzymes
    • nonprotien organic molecules often used as an electron donor or acceptor in a redox reaction.
    • -help in proper enzymatic activity
  29. Biochemical pathways
    • series of reactions in which the product of one reaction becomes the substrate for the next reaction.
    • -regulated by feedback inhibition
  30. Feedback inhibition
    the end product of the pathway is an inhibitor of an earlier enzyme in the pathway
  31. autotrophs
    able to produce their own organic molecules through photosynthesis
  32. heterotrophs
    live on organic compounds produced by other organism
  33. cellular respiration
    • used by all organisms to extract energy from organic molecules
    • -series of reactions that are oxidations, dehydrogenations
  34. dehydrogentation
    • lost electrons are accompanied by hydrogen
    • what is actually lost is a hydrogen atom (1 elec. 1 proton)
  35. NAD+
    during redox reactions, electrons carry energy from one molecule to another.

    • NAD+ is a electron carrier
    • it accepts 2 electrons and 2 proton to become NADH
    • this reaction is reversible
  36. Aerobic Respiration
    final electron receptor is oxygen (O2)

    • C6H12O6+6O2-->6CO2+6H2O
    • glucose + oxygen-->carbon dioxide + water
  37. Anaerobic respiration
    final electron acceptor is an inorganic molecule (not O2)
  38. Fermentation
    final electron acceptor is an organic molecule
  39. Goal of respiration:
    • to produce ATP
    • -energy is released from oxidation reaction in form of electrons
    • -elec. are shuttled by electron carriers (NAD+) to electron transport chain
    • -elec. energy is converted to ATP at the elec. transport chain
  40. Cells are able to make ATP via:
    -substrate-level phosphorylation: transfering a phosphate directly to ADP from another molecule


    oxidative phosphorylation: use of ATP synthase and envery derived from a proton (H+) gradient to make ATP
  41. Oxidation of Glucose steps:
    • glycolysis
    • pyruvate oxidation
    • krebs cycle
    • electron transport chain
  42. Glycolysis
    • converts glucose to pyruvate
    • occurs in cytoplasm
    • 1 glucose = 2 pyruvate
    • products of glycolysis:
    • 2NADH
    • 2 ATP
    • 2 pyruvate
    • for glycolysis to cont. :
    • NADH be recycled to NAD+ by: aerobic (when O2 is available as final elec. accept.)
    • fermentation (when oxy. isnt avail. & organic molecule is final elec. accept.
  43. Fate of pyruvate depends on...
    oxygen availability.

    with O2: pyruvate is oxidized to acetyl-CoA & enters Kerbs cycle

    w/out O2: pyruvate reduced to oxidize NADH back to NAD+
  44. Informative