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Exam next Friday

Exam next Friday. Proposal: 60 point 4 th exam over chapters 10 (Lipids), 11 (Membranes), 13 (Bioenergetics (ATP & redox) 140 point final: ~40 points new stuff (general concepts in glycolysis, TCA, electron transport), ~100 points “comprehensive” Review sheet (4 th exam) this weekend

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Exam next Friday

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  1. Exam next Friday • Proposal: • 60 point 4th exam over chapters 10 (Lipids), 11 (Membranes), 13 (Bioenergetics (ATP & redox) • 140 point final: ~40 points new stuff (general concepts in glycolysis, TCA, electron transport), ~100 points “comprehensive” • Review sheet (4th exam) this weekend • Review for 4th exam on Tuesday(?) • Review for final ~ couple of days next week

  2. Nutrients: Fats/Carbohydrates/Proteins (highly reduced compounds) Glycolysis, TCA/Krebs cycle Breakdown of nutrients Harvesting of energy as (some) ATP, lots of reducing power (NADH) Oxidative phosphorylation (Electron transport) Harvesting of energy from reducing agents Generation of (lots of) ATP Usable (bioavailable) chemical energy: ATP (other phosphorylated cpds), reducing agents (eg. NADH)

  3. Aerobic respiration of glucose (etc) • Glycolysis: • Start with glucose (6 carbon) • Generate some ATP, some NADH, pyruvate (2 x 3 carbon) • TCA cycle • Start with pyruvate • Generate acetate • Generate CO2 and reduced NADH and FADH2 • Electron transport • Start with NADH/FADH2 • Generate electrochemical H+ gradient • Oxidative phosphorylation • Start with H+ gradient and O2 (and ADP + Pi) • Generate ATP and H2O

  4. Glycolysis • Pathway for D-glucose degradation • Generation of pyruvate • Anerobic (no O2 required) • Occurs in most every living cell • Eukaryotes→ in cytosol • Pyruvate has different fates • Aerobic→CO2→ ATP • Anerobic • Fermentation to EtOH • Fermentation to lactate

  5. Glycolysis • 5 step preparatory phase • Energy requiring • 2 ATP invested • Phosphorylation • Isomerization • Phosphorylation • Cleavage • Isomerization

  6. Why phosphorylation? • Coupled transfer of phosphate to/from ATP • Intermediates “trapped” within the cell • Energy required to keep ‘naked’ glucose in the cell (vs. chemical gradient) • Phosphate groups (neg charge) easily retained • Binding energy • Enzymes take advantage of negative charge to increase affinity/specificity

  7. Glycolysis • 5 step payoff phase • 4 ATP generated (net 2 gained) • 2 NADH gained • 2 pyruvate • Series of oxidation and phosphorylation steps

  8. Step 1: Glucose phosphorylation by hexokinase

  9. Step 2: Conversion to Fructose-6-P

  10. Step 3:Phosphorylation to F-1,6-bisP phosphofructokinase *Committed step* Regulatory enzyme

  11. Step 4: Cleavage of F-1,6-bP 6 carbon sugar → Two 3 carbon sugars (triose phosphates)

  12. Step 5: isomerization of dihydroxyacetone Both 3 carbon sugars are now the same (glyceraldehyde 3-P)

  13. “Payoff phase”Step 6: oxidation (phosphorylation) of G-3-P

  14. Step 7: ATP formation Steps 6 & 7 Overall: transfer of Pi from glyceraldehyde 3-P to ATP with 1,3-BPG as an intermediate “Substrate-level phosphorylation”

  15. Step 8: Rearrangement to 2-phosphoglycerate

  16. Step 9: Dehydration of 2-phosphoglycerate to PEP

  17. Step 10: Phosphoryl transfer to ADP

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