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Energy and Enzymes Ch. 6

Energy and Enzymes Ch. 6. How enzymes work. Some enzymes need activation Ex, allosteric activation. enzyme active site. allosteric activator. vacant allosteric binding site. active site cannot bind substrate. active site altered, can bind substrate. How enzymes (don’t) work.

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Energy and Enzymes Ch. 6

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  1. Energy and EnzymesCh. 6

  2. How enzymes work • Some enzymes need activation • Ex, allosteric activation enzyme active site allosteric activator vacant allosteric binding site active site cannot bind substrate active site altered, can bind substrate

  3. How enzymes (don’t) work • Some molecules interfere (“enzyme inhibitors”) • Two main types: • 1) Competitive inhibitor: blocks active site

  4. How enzymes (don’t) work • 2) Allosteric inhibitor: binds on enzyme so active site changes shape

  5. How enzymes (don’t) work • Inhibition temporary: “reversible inhibition” • Cell regulates enzyme activity • Control number enzymes inhibited

  6. How enzymes (don’t) work • Inhibition permanent: “non-reversible inhibition.” • Inhibitor binds permanently! • Many poisons! “Every rose has its thorn…” Poison (1980s)

  7. Poisons as enzyme inhibitors • Antibiotics: Penicillin. Inhibits enzyme makes bacteria cell wall. Bacteria colonies growing in a petri dish

  8. Poisons as enzyme inhibitors • Pesticides: Ex, malathion. Inhibits enzyme insect nerves A wasp

  9. Poisons as enzyme inhibitors • Human poisons: Ex, nerve gas. • VX (“The Rock”) • Sarin (used by Saddam Hussein). VX gas spheres in “The Rock” Bush and Hussein......

  10. What else affects enzyme function? • Shape = function for enzymes! • What affects enzyme shape?

  11. What else affects enzyme function? • Shape = function for enzymes! • What affects enzyme shape? • pH • Temperature

  12. What else affects enzyme function? • Maximum activity: “optimum” • Protein shape changed (non-functional) is “denatured”

  13. What else affects enzyme function? • Temperature ex: bacteria in hot springs • Thermophilic bacteria • “thermo-”= heat • “-philic” = loving

  14. What else affects enzyme function? • pH optima: 2 human enzymes • Lab #5: graph effect pH & temp. on enzymed

  15. The End • Of material for knowledge demo #1!

  16. Releasing Chemical Energy (Ch. 8) • Giant panda snacking on bamboo

  17. Flashback: Chemical Reactions Reactants Products 2 H2 + O2  2 H2O

  18. Linear Pathway: Cyclic Pathway: A B C D E F K J I G M L N H Branching Pathway: Pathways Energy transfers: chemical pathways Several types: Linear, Cyclic, Branching A B C D E F

  19. Getting energy for cells • ATP: spendable energy • Your ATP: run out in 1 minute! • Where from? How made? Why need oxygen?

  20. Energy Q & A • Where energy in molecules? • How energy transferred 1 molecule to another?

  21. Energy in molecules • Organic molecules: energy in covalent bonds C • C-H bond: high energy bond • Electrons high energy • C-O bond: low energy bond • Electrons low energy • Count bonds to determine energy level molecule.

  22. Energy in covalent carbon bonds • Ex, Methane: CH4 (Natural gas) • All C-H bonds • Burns easily! H H C H H

  23. Energy in covalent carbon bonds • Ex, Carbon Dioxide: CO2 • All bonds C-O bonds • Low energy: Fire extinguishers O C O

  24. Energy in biological molecules (cereal box chemistry) • Carbohydrates • Mix C-H & C-O bonds • 4 calories (cal.)/gm

  25. Energy in biological molecules • Proteins • Mix C-H & C-O bonds • 4 cal/gm

  26. Energy in biological molecules • Lipids: Lots high-energy C-H bonds! • 9 cal/gm!

  27. Transferring electrons • Chemistry, involves oxidation & reduction • Oxidation: loss electrons • Reduction: gain electrons • OILRIG: “Oxidation Is Loss, Reduction Is Gain” • Biology, electrons don’t travel alone • H “atomic chaperone”: accompanies electrons.

  28. Transferring electrons • Addition H & electrons: reduction • Endergonic (result: high energy molecule) • Removal H & electrons: oxidation • Usually replace H with O • Exergonic (result: low energy molecule) • Energy released: can make ATP.

  29. Electron carriers • Molecules: can hold high-energy electrons • We see 3 in next 2 weeks: • NAD • FAD • NADP Temporarily hold high energy electrons.

  30. Focus on NAD • Electron-empty (NAD+) or electron-full (NADH) • Gain electrons (& H) makes NAD+ into NADH (reduction) • Loss electrons (& H) makes NADH into NAD+ (oxidation)

  31. Focus on NAD Ex: NAD+ becoming NADH, using H & electrons from a reaction.

  32. How make ATP (2 ways!) • Phosphate + ADP + energy forms ATP + H2O (energy cycle). ATP energyoutput energy input ADP + Pi

  33. How to make ATP (2 ways!) • 1) direct phosphorylation • High energy phosphate from molecule transferred directly to ADP

  34. How to make ATP (2 ways!) • 2) Electron Transport Chain (E.T.C.) • Involves: • a) membrane that H+ cannot cross • b) Electron Transport Chain (series electron carriers: hand off electrons from one to another).

  35. How to make ATP (2 ways!) • Electron Transport Chain (E.T.C.)Involves: • c) concentration gradient H+ • d) ATP synthase: special gate (enzyme) allows H+ to cross, released energy used to make ATP. • Facilitated diffusion!.

  36. How to make ATP (2 ways!) • 2) E.T.C. • H+ concentrated top • Diffuses bottom thru gate (ATP synthase) • Energy released: makes ATP.

  37. Making ATP: Ch. 8 • Aerobic respiration & Photosynthesis: cycle SUNLIGHT PHOTOSYNTHESIS 6CO2 + 6H2O C6H12O6 + 6O2 AEROBIC RESPIRATION

  38. Summary Equation for Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O glucose oxygen water carbon dioxide Making ATP: Ch. 8 • Aerobic respiration • Harvest energy from C-H bonds (slow, step-by-step)

  39. Summary Equation for Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O glucose oxygen water carbon dioxide Now, harvesting ATP from molecules • Overall chemical equation aerobic respiration • Know reactants and products

  40. C: Oxidized! Energy in C-H bonds used make ATP • H & electrons transferred from C to O2: make H2O • Low energy C (CO2) produced(+ energy!)

  41. Harvesting energy: 2 ways • One big step (burn sugar!).

  42. Harvesting energy: 2 ways • Many small controlled steps (aerobic respiration).

  43. Summary Equation for Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O glucose oxygen water carbon dioxide Harvesting energy: 2 ways • Chemical equation same! • Glucose + oxygen gives carbon dioxide + water and energy.

  44. Harvesting energy: 2 ways • Aerobic respiration efficient: 40% energy in glucose made into ATP.

  45. Aerobic Respiration Steps • 1) Glycolysis 2) Krebs Cycle 3) E.T.C.

  46. Step 1: Glycolysis • In cytoplasm (cytosol: not organelle) • Start: glucose (6 C sugar), electron-empty NAD (NAD+), ADP, phosphate • End: 2 ATP, two 3-C molecules (pyruvic acid), two NADH.

  47. Step 1: Glycolysis • ATP made how?: direct phosphorylation

  48. Step 1: Glycolysis • Yields: • 2 ATP (hooray!) • 2 NADH (reduced electron carrier). Has high energy electrons • 2 pyruvic acid (3-C pieces: C-H bonds). Lots energy Pyruvic acid

  49. Where are we now? • Glycolysis done, now Krebs Cycle.

  50. Step 2: Krebs Cycle Flashback to Ch. 4: mitochondrion • In mitochondrion

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