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Lecture #7

Lecture #7. Introduction to Metabolism & Enzymes. Energy. the capacity to cause change the ability to do work Kinetic Energy Thermal energy Potential Energy. Thermodynamics. The study of energy transformations that occur

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Lecture #7

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  1. Lecture #7 Introduction to Metabolism & Enzymes

  2. Energy • the capacity to cause change • the ability to do work • Kinetic Energy • Thermal energy • Potential Energy

  3. Thermodynamics • The study of energy transformations that occur • Law #1 – Energy can neither be created nor destroyed; it can only be transferred and transformed

  4. Chemical Potential Energy A + B ↔ C + D The potential energy available for release in a chemical reaction Potential energy - stored energy that can be used to transfer energy from one system to another

  5. G and DG • Gibbs free energy - the energy portion of a system available to do work – when temperature and pressure are constant • DG – the change in free energy that happens when a system changes DG = Gend – Gstart

  6. What DG means…. A + B ↔ C + D • if DG is negative – the ending free energy is lower than the starting free energy • therefore, there has been a release of energy – energy must have been transferred or transformed – spontaneous reaction • If DG is positive – the ending free energy is higher than the starting free energy • Energy is absorbed by the system - non-spontaneous reaction

  7. Exergonic reaction • energy is released • the DG value is less than 0 (negative) • spontaneous • the DG value represents the theoretical maximum amount of work (quantity of energy that can be transferred to another system) • Endergonic reaction • energy is absorbed and stored • the DG value is grater than 0 (positive) • non-spontaneous • the DG value represents the amount of energy required to drive the reaction

  8. Respiration/Photosynthesis C6H12O6 + O2↔ 6CO2 + 6H2O forward reaction: DG = -686 kcal/mol reverse reaction: DG = 686 kcal/mol

  9. Equilibrium • balance • when a chemical reaction proceeds at the same rate as its reverse reaction, with no change in the amount of each compound • lowest possible free energy (G) value • a system in balance cannot spontaneously change • Must push the system away from the balance

  10. Equilibrium in Metabolism? C6H12O6 + O2→ 6CO2 + 6H2O O2 O2 C6H12O6 + O2→ 6CO2 + 6H2O C6H12O6 CO2 C6H12O6 CO2

  11. ATP Pi ATP ADP DG=-7.3 kcal/mol P

  12. Ca2+-ATPase – skeletal muscle Ca2+ Ca2+ Ca2+ CYTOPLASM ATP P Ca2+ Ca2+ Ca2+ ER LUMEN Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+ Ca2+

  13. Enzymes • a protein catalyst • catalyst – speeds up a chemical reaction

  14. E + S ↔ ES ↔ E + P

  15. E + S ↔ ES ↔ E + P

  16. E + S ↔ ES ↔ E + P

  17. Continued tomorrow and in today’s lab session……..

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