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Energy Flow Through Cells

Energy Flow Through Cells. Energy . What are some of the reasons that cells require energy?. Energy. From where do organisms get the energy they need?. Bioenergetics. What is the difference between and open and a closed system from the standpoint of energy?. What kind of a system is a cell?.

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Energy Flow Through Cells

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  1. Energy Flow Through Cells

  2. Energy • What are some of the reasons that cells require energy?

  3. Energy • From where do organisms get the energy they need?

  4. Bioenergetics • What is the difference between and open and a closed system from the standpoint of energy? What kind of a system is a cell?

  5. Bioenergetics • What is the unit used to measure energy changes in cells? • How do we define this unit?

  6. Bioenergetics • What does the first law of thermodynamics say? • What do we mean by the internal energy of a system? energy stored = energy in – energy out

  7. Bioenergetics • What is enthalpy and how is it related to internal energy? H = E + PV or ΔH = ΔE + ΔPV What happens to ΔH in an exothermic reaction? an endothermic reaction?

  8. Bioenergetics • What does the second law of thermodynamics tell us? • For what purpose do cell biologist make use of this law?

  9. Bioenergetics • What is the relationship between entropy and thermodynamic spontaneity? • How can the order within a cell or the entropy of a reaction decrease?

  10. Bioenergetics • To determine whether a particular reaction will take place in a cell we use the concept of free energy. • What is the relationship between the change in free energy, enthapy and entropy? ΔG = ΔH - TΔS

  11. Bioenergetics

  12. Bioenergetics • How can we determine from the value of ΔG whether a reaction will occur spontaneously? • What enables us to characterize reactions as endergonic or exergonic?

  13. Bioenergetics

  14. Bioenergetics • How can we use the equilibrium constant to determine whether a reaction can occur in a specific direction? Keq = [product]eq/[reactant]eq for glucose-6-PO4 fructose-6-PO4 Keq = [fructose-6-PO4]eq/[glucose-6-PO4]eq = 0.5

  15. Bioenergetics • reactions proceed toward equilibrium

  16. Bioenergetics • How do we actually calculate ΔG? aA + bB cC + dD ΔG = -RTlnKeq + RT ln [C]c[D]d/[A]a[B]b R = 1.987 cal/mol-oK T at 25oC = 298oK

  17. Bioenergetics • What is the difference between ΔG’ and ΔGo’? • How does this affect the actual calculation? since ΔGo’ = - RT ln K’eq ΔG’ = ΔGo’ + 592 ln [C]c[D]d/[A]a[B]b

  18. Bioenergetics

  19. Bioenergetics • How does the cell biologist use the value of ΔG’ ?

  20. Bioenergetics • Why do cellular reactions never reach equilibrium? • What is the steady state and how is it maintained?

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