1. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 6 Energy and Metabolism

2. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Energy Capacity to do work, which is any change in the state or motion of matter Measured as heat energy Unit of measure is the kilocalorie (kcal)

3. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Potential energy Capacity to do work owing to position or state Chemical energy is potential energy stored in chemical bonds Kinetic energy Energy of motion

4. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Closed system does not exchange energy with its surroundings Organisms are open systems

5. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Closed and open systems

6. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism First law of Thermodynamics Energy cannot be created or destroyed Energy can be transferred and changed in form Organisms cannot produce energy, but as open systems, they can capture it

7. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Second law of Thermodynamics Entropy is continuously increasing No energy transfer is 100% efficient Some energy is dissipated as heat Organisms maintain their organization only with input of energy from surroundings

8. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Metabolism Sum of all the chemical activities taking place in an organism Anabolism –Complex molecules synthesized from simpler substances Catabolism –Larger molecules broken down into smaller ones

9. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Enthalpy is total potential energy of a system As entropy increases, amount of free energy decreases H = G + TS –H is enthalpy –G is free energy –S is entropy –T is absolute temperature in degrees Kelvin

10. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Exergonic reaction Releases energy that can perform work In coupled reaction, supplies input of free energy to drive an endergonic reaction Endergonic reaction increases free energy

11. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Exergonic and endergonic reactions

12. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Dynamic equilibrium In a chemical reaction, rate of change in one direction is the same as in the opposite direction When concentration of reactant molecules increases, the reaction shifts until equilibrium is re-established

13. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Adenosine triphosphate (ATP) Holds readily available energy for very short periods Donates energy by means of terminal phosphate group Common link between –Exergonic and endergonic reactions –Catabolism and anabolism

14. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism ATP and ADP

15. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism ATP links exergonic and endergonic reactions

16. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Redox reactions Substance that becomes oxidized gives up energy Substance that becomes reduced receives energy Essential part of cellular respiration, photosynthesis, and other chemical reactions

17. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism NAD

18. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Enzymes Biological catalysts Cells regulate the rate of chemical reactions with enzymes Lower activation energy (energy required to break existing bonds) Although most enzymes are proteins, some types of RNA molecules have catalytic activity as well

19. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Enzymes Work best at specific temperature and pH conditions Catalyze virtually every chemical reaction that takes place in an organism Some enzymes consist only of protein Some enzymes have two components –Protein called apoenzyme –Cofactor

20. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Important classes of enzymes [insert table 6-1 when available]

21. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Feedback inhibition Formation of an end product inhibits an earlier reaction in the metabolic pathway

22. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Feedback inhibition

23. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Reversible inhibition Competitive inhibition –Inhibitor competes for the substrate for the active site Noncompetitive inhibition –Inhibitor binds with enzyme at a site other than active site Irreversible inhibition –Inhibitor combines with an enzyme and permanently inactivates it

24. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 6 Energy and Metabolism Competitive and noncompetitive inhibition