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Transit and Metabolic Maps: Complex and Functional

Explore the intricate metabolic pathways of glycolysis and cellular respiration, ATP as a universal energy currency, and the role of activated carriers in energy transfer. Learn how organisms optimize energy generation through various metabolic processes. Dive into substrate-level ATP phosphorylation and the regulation of metabolic pathways.

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Transit and Metabolic Maps: Complex and Functional

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  1. Transit and Metabolic Maps: Complex and Functional

  2. Glycolysis Coupled with Cellular Respiration Maximizes Energy Generation

  3. Carbon Oxidation is Coupled with Energy Rich Reduction Which molecule is more energy rich on a per carbon basis?

  4. Free-Energy Universal-Currency: ATP ATP hydrolysis is exergonic ATP + H2O ADP + Pi ∆G°ʹ = - 30 kJ/mol ATP hydrolysis drives metabolism in heterotrophs Light energy is trapped as ATP in phototrophs Why is ATP an excellent energy currency?

  5. ATP: High Phosphoryl-Transfer Potential • ATP and hydrolysis products differences: • Electrostatic repulsion • Resonance stabilization • Hydration stabilization How can an energetically unfavorable reaction be made spontaneous?

  6. Substrate-Level ATP Phosphoryation Requires High Phosphoryl-Transfer Potential Standard Free Energy of Hydrolysis

  7. Duration of Alternative Energy Sources Anaerobic SystemsAerobic Systems ATP: tennis serve Oxidative phosphorylation: Creatine phosphate: sprint race > 500 m Glycolysis: 200 m dash

  8. ATP: A Multifunctional Metabolite High turnover (ca. 90 lbs/24 hrs)

  9. Additional Activated Carriers Nicotinamide Adenine Dinucleotide (NAD+) Electron carriers in oxidation-reduction reactions NADH functions in catabolism NADPH functions in anabolism Nicotinamide Adenine Dinucleotide Phosphate (NADP+)

  10. Additional Activated Carriers Electron carriers in oxidation-reduction reactions FADH functions in both catabolism and anabolism Flavin adenine dinucleotide (FAD)

  11. Substrate Specificity for Dinucleotide Oxidation-Reduction Reactions

  12. Fatty Acid Biosynthesis via Keto Reduction to a Methylene Unit What is the reducing agent for this reaction?

  13. Coenzyme A: an Activated Carrier of Two Carbon Fragments Coenzyme A structure Acetyl CoA + H2O ↔ Acetate + CoA + H+ ∆G°ʹ = -31 kJ/mol

  14. Activated Carries Utilized in Metabolism

  15. Coenzymes Derived from Vitamins What coenzymes are derived from these vitamins?

  16. Metabolic Regulation • Substrate accessibility (compartmentalization) • Enzyme amount (transcriptional and translation control) • Catalytic activity • (allosteric control, • covalent modifications, • hormone signaling, and • cell energy status) Energy charge = [ATP] + ½[ADP]/([ATP] + [ADP] + [AMP])

  17. Energy Utilization Linked with Building and Degrading Metabolites What macromolecules are stored and/or metabolized by humans for energy?

  18. Metabolic Fuel Generation by Digestion Match the enzyme with the reaction: - Protease - Amylase - Lipase

  19. Lipid Transport via Lipoproteins (aka Chylomicrons) to Adipocytes Lipoproteins - esterified cholesterol, proteins and triacylglycerols combined Adipose cells

  20. Human Sugar Storage in Liver and Muscle Tissue A Liver Cell Glycogen molecule with sugar units Fat globule Glycogen granules Mitochondria What advantages are there in having glycogen be a branched polymer?

  21. Glycogen Degradation by Glycogen Phosphorylase (Phosphorolysiss) Trapped in the cell

  22. Protein Degradation by Ubiquitin Tagging and Proteasome Digestion Protease active sites Cutaway view showing inner chamber

  23. Proteasome Protein Degradation Protein turnover important in: Cell signaling Maintaining high protein quality

  24. Test Your Knowledge… Does this phosphoarginine metabolite rich in the muscles of certain invertebrates have a high phosphoryl-transfer potential? What function might this metabolite have?

  25. ∆G of ATP Hydrolysis with Varying [Mg2+] How does decreasing [Mg+2] affect ∆G of ATP hydrolysis? Can this trend be justified?

  26. Problems: 26, 27 and 41

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