1. Metabolism Chapter 8

2. Energy, Enzymes & Respiration 1.Energy – Energy balance – Reactions & energy – ATP 2.Enzymes – Activity – Environmental effects 2

3. Energy Potential Energy – stored energy Kinetic Energy – active energy 3

4. 4 A) Potential Energy High; Kinetic Energy Low B) Potential Energy & Kinetic Energy equal C) Potential Energy Low; Kinetic Energy High

5. Free Energy (G) Movement from unstable high energy state to more stable low energy state – releases free energy 5

6. Exergonic/Enderg onic Exergonic – a release of energy (energy outward) – Spontaneous Endergonic – requires energy investment (energy inward) 6

7. Free Energy ΔG= ΔH - TΔS ΔG = change in free energy ΔH = Change in enthalpy (total energy) T = temperature (kelvin) ΔS = Change in entropy 7

8. Hydroelectric systems Movement of water from chamber A to B powers a turbine Water will continue to move down, releasing free energy Water above has more free energy that can be used. – Stored potential energy 8

9. Metabolism Catabolism – breakdown/digestion of a reagent into multiple products Anabolism – synthesis of product from one or more reagents Bioenergetics – how energy flows through living organisms 9

10. Energy balance Energy input = energy output 10

11. Metabolism 11

12. Dehydration & hydrolysis Synthesis results in creation of water Breakdown uses water 12 Fig 5.2

13. Energy in organisms Energy is consumed to create bonds Energy is released when bonds are broken ATP 13

14. ATP Adenosine triphosphate 14

15. ATP 15

16. The ATP Cycle Energy is released by breaking down by catabolism Energy is stored (potential) by anabolism 16

17. Cellular Work Cell can do three types of work: Chemical Transport Mechanical 17

18. Exergonic reactions Reactants must absorb enough energy to reach the unstable transition state for reaction to proceed 18

19. Endergonic reactions Reactants must absorb enough energy to reach the unstable transition state for reaction to proceed 19 ΔG ≥ 0

20. Metabolic reactions – Anabolism Molecule Construction Energy storage – Catabolism Molecule Break down Energy release 20

21. Metabolic Processes Photosynthesis (Anabolism) Cell respiration (Catabolism) ATP use (Catabolism) Building storage molecules (Anabolism) – starch or glycogen & triglycerides 21

22. Metabolic reactions Reactants and products Energy (heat and ATP) Enzymes Glucose + oxygen CO 2 + water + ATP + heat enzymes 22

23. Metabolic reactions Reactants = Molecules that go into a reaction Products = Molecules that come out of a reaction Glucose + oxygen CO 2 + water + ATP + heat enzymes 23 ReactantsProducts

24. Metabolic reactions Energy release by breaking down larger complex molecules However, requires an initial investment of energy Glucose + oxygen CO 2 + water + ATP + heat enzymes 24 Products Reactants

25. Activation Energy Energy investment necessary to start a reaction 25

26. Enzymes and energy In most cases, reactions cannot occur without the enzyme 26 Enzymes are Proteins – End in -ase lower the activation energy needed for a reaction to occur

27. Enzymes 27

28. Enzymes 28

29. Enzymes 29

30. Optimal Conditions Vary Optimal operating conditions vary with the organism – Human enzymes, and gut endosymbiants (E.coli) have an optimal temp of 37 o c – Within the body optimal enzyme pH varies Stomach (highly acidic) Intestines (pH neutral to slightly basic) 30

31. Enzymes & environments Enzymes must run into reactants However Protein 3-D structure is affected by environment (temperature, pH, salts) – Outside the optimal range and enzymes cease to work 31

32. Multistep reactions Some products are the result of several reactions, each controlled by a different enzyme 32

33. Inhibitors Molecules that bind enzymes making them (temporarily) inactive 33

34. Allosteric Regulation Reversible non- competitive inhibitors Can stimulate (activate) or inhibit enzyme activity 34

35. Feedback Inhibition The final product of a metabolic pathway is also its inhibitor Useful in regulating pathways that are density dependent 35

36. Location, Location, Location Enzymes are not randomly dispersed throughout the cell Compartmentalized in specific organelles Locations include – Lysosomes – Vacuoles – Mitochondria 36

37. 37

38. Enzymes & Metabolism Example: Amylase An enzyme that digests starch (complex carbohydrate) into maltose (simple carbohydrate). What do the molecules in this reaction look like? 38

39. Enzymes & Metabolism Will this reaction use or release energy? Why does amylase need to be added both before and after the stomach? 39