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Reading for today on glycolysis: pp. 221-234 Homework due today: Problems 8-5, 8-7 In both problems, use the favorable free energy change of ATP hydrolysis to drive the unfavorable transport of solute up its concentration gradient on a per mole basis.

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  1. Reading for today on glycolysis: pp. 221-234 Homework due today: Problems 8-5, 8-7 In both problems, use the favorable free energy change of ATP hydrolysis to drive the unfavorable transport of solute up its concentration gradient on a per mole basis. Reading for Wednesday, Feb. 21 on fermentation and TCA cycle: 236-241, 248-258 Reading for Friday, Feb. 23 on integration of metabolism: 258-262 Reading for Monday, Feb. 26 on respiration: 265-271 Homework due Monday, Feb. 26: Problem 9-5 Convert all concentrations to M, and your answer will be in M. Don’t worry about [H+] – use equations as given in problem. Determine [glucose] at equilibrium (ΔG’ = 0); then a concentration greater than this will favor production of G6P. Wednesday, Feb. 28 on respiration: 271-283 Friday: Exam 2 on Days 12-22, 99 points, 33 m/c questions. Note Exam 3 will be worth 81 points. Announcements

  2. CHO metabolism Metabolic reactions and ATP Oxidation-reduction reactions Glycolysis After reading the text, attending lecture, and reviewing lecture notes, you should be able to: Describe the roles of ATP/ADP and NAD+/NADH in biological reactions. Summarize the purpose and place, reactants and products, critical enzymes, and net yield of glycolysis. Calculate free energy changes associated with glycolysis. Summarize the products, control steps, etc. of glycolysis. Outline/Learning Objectives

  3. Catabolic (degradative) Glycolysis, fermentation TCA cycle, electron transport, oxidative phosphorylation Glycogenolysis Fatty acid oxidation Amino acid degradation Anabolic (synthetic) Gluconeogenesis Glycogen synthesis Fatty acid synthesis Amino acid synthesis Catabolic and Anabolic Metabolic Pathways

  4. ATP is an energy intermediate Donates Phosphate; Hydrolysis is exergonic Accepts Phosphate; Synthesis is endergonic

  5. Oxidation and Reduction • Oxidation: gives up e- • Dehydrogenation: gives up H+ • Reduction: accepts e- • Hydrogenation: accepts H+ • Redox reactions • Usually involve 2 e-, 2 H+ in the cell • Catalyzed by dehydrogenases

  6. NAD+ accepts, NADH donates e-

  7. NAD+/NADH is an intermediate e- acceptor/donor • Its redox reaction is coupled to another redox reaction in metabolic pathways: NADH + H+  NAD+ + 2e- + 2H+ Acetaldehyde + 2e- + 2H+  ethanol Acetaldehyde + NADH + H+  ethanol + NAD+ This fermentation reaction is catalyzed by alcohol dehydrogenase.

  8. Final e- Acceptors • Glycolysis, fermentation (NAD+) • No net oxidation of glucose • Aerobic respiration O2 • Complete oxidation of glucose using O2 as final e- acceptor: ½ O2 + 2 H+ + 2 e- H2O • Anaerobic respiration S, H+, Fe3+ • Complete oxidation of glucose using something other than O2 as final e- acceptor. • Glycolysis is the central catabolic pathway and first part of aerobic respiration:

  9. C6H12O6 + 6 O2 6 CO2 + 6 H2O Go’ = -686 kcal/mol In bomb calorimeter, the large EA of this rxn is overcome by heat of fire. In the cell, a series of reactions with small EA is overcome by body temperature and enzymes. Purpose: convert chemical bond energy of glucose to chemical bond energy in ATP Oxidation of Glucose

  10. Glycolysis Problems 2-88 2-89 2-90 2-93

  11. cellular Conc., pH=7 1 M Conc., pH=7 Energetics of Glycolysis The table above shows free energy change values in kcal/mol for the concentrations of intermediates in red blood cells. The overall ΔG’ from glucose to pyruvate is about -20 kcal/mol.

  12. Glycolysis Summary • Cytoplasmic • Catabolism of: • carbohydrates  G6P, F6P • fats: glycerol  DHAP • some amino acids  pyruvate • Cost = 2 ATP, Gain = 4 ATP, Net Gain = 2 ATP • Reduced Coenzymes: 2 NADH + H+ • End product: pyruvate (CH3COCOO-) • Control steps: irreversible reactions 1, 3, and 10

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