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Ch.6: Introduction to Metabolism

Ch.6: Introduction to Metabolism. Metabolism, Transformation of energy, ATP laws of thermo-dynamics Enzymes, Controls of metabolism. YIKES!!! Metabolic pathways. What is Metabolism? Put the following words into one of these two categories:. Anabolic Catabolic

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Ch.6: Introduction to Metabolism

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  1. Ch.6: Introduction to Metabolism Metabolism, Transformation of energy, ATPlaws of thermo-dynamics Enzymes, Controls of metabolism

  2. YIKES!!!Metabolicpathways

  3. What is Metabolism?Put the following words into one of these two categories: AnabolicCatabolic exergonic, endergonic, nonspontaneous, spontaneous, -ΔG, +ΔG, uphill, downhill, respiration, photosynthesis ATP ADP + Pi, ADP + Pi  ATP loss of free energy (G), gain of free energy (G) products have greater G than reactants, reactants have greater G than products absorbs free energy from surroundings, releases free energy to surroundings hydrolysis, condensation/dehydration ΔG= -686 kcal/mol, ΔG= 686 kcal/mol C6H12O6 + O2  H20 + CO2, H20 + CO2  C6H12O6 + O2

  4. What is Metabolism?Put the following words into one of these two categories: AnabolicCatabolic exergonic, endergonic, nonspontaneous, spontaneous, -ΔG, +ΔG, uphill, downhill, respiration, photosynthesis ATP ADP + Pi, ADP + Pi  ATP loss of free energy (G), gain of free energy (G) products have greater G than reactants, reactants have greater G than products absorbs free energy from surroundings, releases free energy to surroundings hydrolysis, condensation/dehydration ΔG= -686 kcal/mol, ΔG= 686 kcal/mol C6H12O6 + O2  H20 + CO2, H20 + CO2  C6H12O6 + O2

  5. ATP’s Structure It is a Nucleotide:Base Sugar Phosphates Hydrolysis of ATP into ADP

  6. 10 million molecules of ATP/second/cell!

  7. Energy Coupling: The use of an exergonic process to drive an endergonic reaction. • Ex: Adding a phosphate group (Pi) to molecules makes them unstable and usually highly reactive • Where does that Pi come from?

  8. Example coupling reaction • ATP’sphosphatemakes GLU more reactive, this is phosphorylation/ energy coupling Note: what is the second law of thermodynamics? Exergonic

  9. What about this example? A + B  AB ΔG = 9.0 kcal/mol ATP+ H2O ADP+Pi ΔG = -7.3 kcal/mol

  10. Closed system Using energy gradients (energy at each step) to help do work. Staying away from equilibrium. (like respiration!) how is a human an open system? Open system

  11. What does free energy have to do with enzymes?

  12. Enzymes • Examples: hexokinase, sucrase, catalase, pepsin, trypsin---all are specific • Substrate(s) enzyme Product(s) The action can be catabolic or anabolic. “Induced fit” not rigid—like a hand shake • http://scholar.hw.ac.uk/site/biology/activity7.asp?outline=no

  13. Negative G= a loss of free Energy The products have less energy than the reactants, EXERGONIC

  14. Enzyme rate and rate of reaction • How does the amount of enzyme affect the rate of the reaction? • How does the amount of enzyme affect the rate of an enzyme? • How does the amount of substrate affect the rate of the reaction? • How does the amount of substrate affect the rate of the enzyme? • What are the differences between competitive and noncompetitive inhibitors. • What is cooperativity? How might this be involved with negative feedback?

  15. Free Energy and Metabolism: • C6H12O6 + 6O2 6CO2 + 6H2O • G = - 686 kcal/mol (-2870 kJ/mol) • Is this Exergonic or Endergonic?• What is this reaction? • 6CO2 + 6H2O C6H12O6 + 6O2 • G = +686 kcal/mol (+2870 kJ/mol) • This reaction is photosynthesis. • Where is the Energy coming from to drive this nonspontaneous reaction?

  16. Energy transformations • 1. First law of thermodynamics:Conservation of energy—it is not lost or destroyed. There is a constant amount in the universe. (what form has the lowest Energy?) • 2. Second law of thermodynamics: Entropy(S), every energy transfer increases entropy of the universe.

  17. G(free energy)=H(total Energy) –TS This change in Energy can be harnessed to do work! Kinetic (KE) and Potential energy (PE)

  18. Glen Canyon Dam in Arizona

  19. Fig 6.12

  20. Toothpickase Demonstration • How many subunits does the enzyme have? __ • What is the quaternary structure for your enzyme? ____________ • Where is your active site? ______________ • What are the products of the reaction of toothpickase with its substrate? __________ • Is the enzyme changed in any way throughout the reaction? ________

  21. Calculating the V-Max of toothpick-ase under normal conditions

  22. ENZYMES:pH and temperature sensitive • Most will DENATURE when out of range

  23. Competitive inhibitor • Competes forthe active site • Non-competitive inhibitor • Doesn’t compete with the active site

  24. Allosteric enzymes: Activators and Inhibitors (active forms, inactive forms)

  25. Fig 6.16 • Feedback inhibition • Pathwaysswitching off because of an end product acting as an allosteric inhibitor

  26. Allosteric again • Cooperativity: the substrate itself “turns the enzyme on” / activates it

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