Cellular Bioenergetics

Card Set Information

Cellular Bioenergetics
2010-10-19 17:05:46

Biochem block3 Lecture 25 Chapter 4
Show Answers:

  1. What is the first law of thermodynamics?
    The total amount of energy in the universe is constant. Energy can neither be created nor destroyed, but it can be transformed from one form into another.
  2. What is the second law of thermodynamics?
    • The disorder of the universe always increases.
    • In other words, all chemical and physical processes occur spontaneously only when the disorder of the universe increases.
  3. What is the third law of thermodynamics?
    As the temperature of a perfect crystalline solid approaches absolute zero (0 K), disorder approaches zero.
  4. What takes place in a thermodynamic "universe"?
    Open system and Closed system
  5. What is a open system?
    Matter and energy exchanged between system and surroundings (e.g., living organisms)
  6. What is a closed system?
    Only energy can be exchanged between system and surroundings.
  7. What are state functions?
    • Depend only on initial and final state
    • Independent of the path taken to get there
  8. What are 2 examples of state functions?
    Enthalpy and Entropy
  9. What are two examples of non state functions?
    Work and Heat
  10. What are carbohydrates made of?
    Carbon, hydrogen, and oxygen
  11. Changing glucose to gluconic acid is an example of what reaction?
  12. The bond between two monosaccharides is called a:
    Glycosidic bond
  13. Amylopectin is an example of what:
  14. Which of these polysaccharides has a branched chain structure:
    Amylose, amylopectin, glycogen, or cellulose
    Glycogen and Amylopectin
  15. How do oligosaccharide heteroglycans attach to proteins?
    Either the side chain nitrogen of asparagine or the side chain oxygen of serine or threonine
  16. What are typical GAG characteristics?
    • Linear polymers (that can make branches)
    • Repeating disaccharides
    • Carboxyl and/or sulfate groups
    • Amino group substitutions
  17. What are some characteristics of proteoglycans?
    • Extremely high carbohydrate content (up to 95%)
    • Found on cell surface or extracellular matrix
    • Contain GAGs
  18. What is true of glycoproteins?
    1. Large GAG-containing structures
    2. Proteins w/ carbohydrates attached
    3. Found only outside cells.
    Proteins with carbohydrates attached.
  19. What is E?
  20. What is q?
    heat absorbed by a system
  21. What is W?
    Work done by the system
  22. What is H?
  23. What is PV?
    Pressue-volume work done on or by the system
  24. What is the equition for change in energy and which law?
    • ΔE = q + w
    • First law
  25. What is the equation for enthalpy and which law?
    H = E + PV
  26. What is close to zero in biological systems (1st law) and what does that mean to the relation of H and E?
    • ΔPV ≈ 0
    • Therefore:
    • ΔH = ΔE
  27. What does a reaction do when ΔH < 0 and what term describes this?
    • The change in enthalpy is a negative value so the reaction will give off heat energy
    • Exothermic
    • 1st Law of Thermodynamics
  28. What does a reaction do when ΔH > 0 and what term describes this?
    • The change in enthalpy is postive and the reaction absorbs heat energy.
    • Endothermic
    • 1st Law of Thermodynamics
  29. What does a reaction do when ΔH=0 and what term describes this?
    • The is no heat energy exchange with surroundings
    • Isothermic
    • Dead living organism
    • 1st Law of Thermodynamics
  30. What is spontaneous?
    • Physical or chemical changes that occur with the release of energy
    • ex. pysical change of ice melting.
  31. What is Entropy (S) and which law does it apply?
    • Degree of system (anywhere in the system's universe) disorder
    • For bioprocesses, entropy increases take place in the surroundings
    • 2nd Law of Thermodynamics
  32. The more disorder, greater...
    the S (Entropy) value
  33. When is S positive?
    Entropy is positive for a spontaneous process
  34. What is the main equation for 2nd law of Thermodynamics?
    • ΔSuniv = ΔSsys + Δssurr
    • The change may occur in any part of the system
  35. What is + ΔSuniv?
    Means the process is spontaneous
  36. What is −ΔSuniv?
    Means the reverse process is spontaneous
  37. What is nonspontaneous?
    • Processes that occur when a constant input of energy is required to support a change.
    • ex. ice will not form at temperatures above 0 degrees C
  38. Why is the change in free energy useful?
    Since ΔSuniv is too hard to know accurately, free energy change (ΔG) is a more useful measure
  39. What is the equation of free energy change?
    ΔG = ΔH - TΔS
  40. What is free energy and how is it derived?
    • A thermodynamic function that can be used to predict the spontaneity of a process.
    • A state function that relates the first and second laws of thermodynamics
    • Represents the maximum useful work obtainable from a process.
  41. If (-) ΔG, then the reaction is (3 things):
    • Exergonic reaction
    • Spontaneous
    • Favorable
  42. If (+) ΔG, then the reaction is (3 things):
    • Endergonic
    • Nonspontaneous
    • Not favorable
  43. If ΔG = 0, equilibrium, then the reaction is (3 things):
    • At equilibrium
    • No change
  44. If the ΔG for a reaction is negative, then the reverse reaction ...
    • ΔG is positive
    • Non spontaneous
    • Endergonic
    • Unfavorable
  45. Explain the characteristics of the varibles in ΔG = ΔH - TΔS, if the reaction were favorable...
    • If TΔS is significantlly large or positive, then ΔG will be negative.
    • When ΔG is negative the reaction is spontaneous and exergonic which is favorable.
    • ΔSuniv (disorder in the universe) will increase
  46. What is the difference between ΔG, ΔG°, and ΔG°’
    • ΔG: Uniform conditions for calculation
    • ΔG°: Standard free energy change
    • ΔG°': Biochemical standard state
  47. What is ΔG° and its conditions?
    • Standard free energy change is denoted by ΔG°
    • Conditions: 25°C (298 K), 1.0 atm pressure, all solutes at 1.0 M
  48. What is ΔG°' and its conditions?
    • free energy change at biochemical standard state conditions:
    • ΔG° at pH 7
  49. For aA + bB ↔ cC + dD:
    ΔG = ΔG° + RT ln (([C]c[D]d)/([A]a[B]b))
  50. Why do the reactions discussed in bioenergetics still occur with a postive environment (endergonic/unfavorble) in the body?
    Because of absorbed chemical energy from molecules such as ATP.
  51. What is the primary cellular energy source?
    Adenosine triphosphate (ATP)