1. Thermodynamics and Metabolism

2. Metabolism Metabolism = Catabolism + Anabolism
Catabolic reactions are energy yielding
breakdown of more-complex molecules into simpler ones
Anabolic reactions are energy requiring
building up of simpler molecules into more-complex ones

3. Catabolic vs. Anabolic

4. First and Second Laws of Thermodynamics
1st: “Energy can be transferred or transformed but neither created nor destroyed.”
2nd: “Every energy transfer or transformation increases the disorder (entropy) of the universe.”
Note especially the waste heat

5. Energy in the Biosphere
Organisms take in energy & transduce it to new forms (1st law)
As energy transducers, organisms are less than 100% efficient (2nd law)

6. Organisms employ this energy to:
Grow
Protect Themselves
Repair Themselves
Compete with other Organisms
Make new Organisms (i.e., babies)

7. In the process, organisms generate waste chemicals & heat
Organisms create local regions of order at the expense of the total energy found in the Universe!!! We are Energy Parasites!

8. Kinetic and Potential Energy

9. First Law of Thermodynamics:
Energy can be neither created nor destroyed
Therefore, energy “generated” in any system is energy that has been transformed from one state to another (e.g., chemically stored energy transformed to heat)

10. Second Law of Thermodynamics:
Efficiencies of energy transformation never equal 100%
Conversion to heat is the ultimate fate of chemical energy

11. Increase stability
Downhill
G < 0
Greater entropy

12. “Food”
Spontaneous
Potential energy
Waste heat
Forward reaction
Work

13. Types of Reactions

14. Movement toward equilibrium
1. Exergonic Reactions
“Food”
Energy released
Movement toward equilibrium

15. Decrease in Gibbs free energy (-G)
Increase in stability
Spontaneous (gives off net energy upon going forward)
Downhill (toward center of gravity well, e.g., of Earth)
Movement towards equilibrium
Coupled to ATP production (ADP phosphorylation)
Catabolism

16. 2. Endergonic reactions
“Work”
Energy required

18. Exergonic reactions can supply energy for endergonic reactions
Coupling Reactions

19. Energy Coupling in Metabolism
Catabolic reactions provide the energy that drives anabolic reactions forward
Catabolic reaction
Anabolic reaction

20. Adenosine Triphosphate (ATP)

21. Energy Coupling via ATP

22. Hydrolysis of ATP

23. Summary of Metabolic Coupling
Exergonic reaction
Endergonic reaction
Exergonic reaction
Endergonic reaction
Exergonic processes drive Endergonic processes

24. Electron Carriers
Compounds that pick up electrons from energy-rich compounds and donate them to low-energy compounds

25. Electrons that pass from one to another carry energy with them, so the reduced form of a molecule is always at a higher energy level than the oxidized form

26. Chemically stored energy
Anabolic process
Catabolic process
Chemically stored energy