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Ch.6   energy   enzymes
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  • 1. Energy and MetabolismKEY WORDS:EnergyFree Energy (ΔG)Potential energyKinetic energyEnzymeSubstrateActivation energyExergonic reactionEndergonic reactionCatalystATP/ ADP
  • 2. Energy •The capacity to do work •Move matter
  • 3. Energy •The capacity to do work •Move matter
  • 4. Types of energy •Kinetic •Potential Question: __________ is an example of kinetic energy, and __________ is an example of potential energy. 1. Fire; a piece of wood 2. A loaded gun; a flying bullet 3. A rock on top of a hill; a rock rolling down the hill 4. None of these are correct. 5. All of these are correct.
  • 5. Chemical Energy•Stored in chemical bonds -high energy electrons •Some molecules store a lot of energy Carbos, lipids •Some molecules Carbon dioxide, store much less water
  • 6. Chemical Energy •Energy can be transferred/transformed Sugar + oxygen  carbon dioxide + water + heat C6H12O6 + O2  CO2 + H2O + Energy
  • 7. First Law of Thermodynamics:Energy: neither created nor destroyed• Converted from one form to another• Exchanged between substances
  • 8. Second Law of Thermodynamics: All exchanges of energy increase the entropy of the universeEntropy: •Disorder or randomness of a system •Heat is most disorganized form of energy •Reactions that ↑ entropy happen spontaneously & release energy
  • 9. Two laws of thermodynamics
  • 10. Energy Transformed
  • 11. Exergonic Reactions •Release energy •“Spontaneous” •Usually breakdown of complex molecules
  • 12. Endergonic Reactions•Usually involve synthesisof complex molecules•Not “Spontaneous” 6CO2 + 6H2O + Energy C6H12O6 + 6O2 •Require energy
  • 13. Question: Which of the following reactionsis endergonic? 1. CO2 and H2O Glucose 2. Amino acids Proteins 3. Triglycerides Fatty acids 4. Ions moving across membrane from an area of high concentration to an area of low concentration.
  • 14. Question:Which of the following reactions releases energy?1. CO2 and H2O Glucose2. Amino acids Proteins3. Triglycerides Fatty acids4. Ions moving across membrane from an area of high concentration to an area of low concentration.
  • 15. Coupled Reactions Exergonic provides energy for the endergonic Exergonic Endergonic Energy Energy Proteinglucose CO2 + H2O Amino acids
  • 16. Living organisms Metabolism •All chemical reactions in an organismAnabolism Catabolism
  • 17. Living organisms •Capture energy to drive chemical reactions. •Convert “raw” energy into usable form •Sunlight, food ATP En er gy Energy
  • 18. The structure and hydrolysis of ATP
  • 19. ATP: the Cell’s Rechargeable Battery• ATP energy ADP charged battery dead battery• This energy can then be used to run an energy requiring reaction.
  • 20. The ATP cycle
  • 21. According to the first law ofthermodynamics, energy1. is never lost or gained, but is only transformed2. always requires an ultimate source such as the sun3. can never be gained, but can be lost4. can never really be harnessed5. can never be transformed
  • 22. Each time there is a chemical reaction, someenergy is exchanged. According to thesecond law of thermodynamics, with eachexchange1. Some energy is lost, but other energy is created.2. Some energy must come from the sun.3. Some energy is transformed into heat.4. Energy is gained for future use.5. Some energy is permanently and completely destroyed.
  • 23. ATP stores energy in the form of1. mechanical energy2. heat3. complex carbohydrates4. chemical bond energy5. amino acids
  • 24. The complexity of metabolism
  • 25. Equation: Gibb’s Free EnergyΔG = ΔH – TΔS Energy All Energyavailable energy NOTfor work available for work
  • 26. The relationship of free energy to stability, work capacity, and spontaneous change
  • 27. Energy changes in exergonic and endergonic reactions
  • 28. Energy profile of an exergonic reaction
  • 29. Disequilibrium and work in closed and open systems
  • 30. Is ΔG for an exergonic reaction positiveor negative?
  • 31. What is the difference between:AnabolismCatabolismMetabolism
  • 32. From an energy perspective, when isequilibrium reached?
  • 33. EnzymesKEY WORDS:EnzymeActivation energyCatalystSubstrateActive siteInduced fitCoenzymeAllosteric siteCompetitive inhibitorNoncompetitive inhibitorFeedback inhibition
  • 34. Enzymes and ShapeActive Site Induced fit: “Handshake” between substrate and enzyme
  • 35. Activation Energy Activation Energy Net Energy Released
  • 36. Enzymes•Proteins that speed up chemical reactions(catalysts)•Lower activation energy for a reaction
  • 37. Enzyme reactions can be simplified as: E+S ES E +P • S = Substrates (reactants) enter reaction. • P = Product (what you get at the end) result • E = Enzymes mediate specific steps sucrasesucrose + H2O glucose + fructose
  • 38. The catalytic cycle of an enzyme
  • 39. EnzymesKey Points: •Catalyze reactions •Don’t change reactions •Same net release/use of energy •Enzymes are not changed by reaction •Each enzyme catalyzes a specific chemical reaction
  • 40. Enzymes lower the barrier of activation energy
  • 41. Which of the following will lower theactivation energy of a reaction in a cell?1. lowering the temperature2. lowering the pressure3. using an enzyme4. changing the amount of the reactants5. supplying ATP
  • 42. Which of the following will lower theactivation energy of a reaction in a cell?1. lowering the temperature2. lowering the pressure3. using an enzyme4. changing the amount of the reactants5. supplying ATP
  • 43. Enzymes1. accelerate specific chemical reactions2. are not chemically altered by binding with a substrate3. lower the activation energy of specific chemical reactions4. all of the above5. a and c only
  • 44. 4 Things that Affect Enzyme Activity 1. Substrate concentration 2. Enzyme concentration 3. pH Shape of enzyme (Protein denatured) 4. Temperature
  • 45. Environmental factors affecting enzyme activity
  • 46. Enzyme Regulation• Enzymes can be turned on and off• Regulated by other molecules in the cell• Examples: – Allosteric regulation – Feedback inhibition – Inhibitors
  • 47. Inhibition of enzyme activity
  • 48. Allosteric regulation of enzyme activity
  • 49. Feedback inhibition
  • 50. If an enzyme solution is saturated withsubstrate, the most effective way toobtain an even faster yield of products is:a) Add more enzymeb) Heat the solutionc) Add more substrated) Add an allosteric inhibitore) Add a noncompetitive inhibitor
  • 51. An enzyme accelerates a metabolicreaction bya) Altering the overall free energy change for the reactionb) Making an endergonic reaction occur spontaneouslyc) Lowering the activation energyd) Pushing the reaction away from equilibriume) Making the substrate molecule more stable
  • 52. Some bacteria are metabolicallyactive in hot springs becausea) They are able to maintain a cooler internal temperatureb) High temperature facilitates active metabolism w/o need of catalysisc) Enzymes have high optimal temperaturesd) Enzymes are insensitive to temperature
  • 53. Glycolysis is a metabolic pathway that helpsliving things extract energy from food. Fromthis we know that glycolysis1. consists of a series of chemical reactions2. uses a number of enzymes3. involves the modification of a series of substrates4. proceeds by means of each enzyme leaving a succeeding reaction to a different enzyme5. all of the above