10 metabolism lecture
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10 metabolism lecture Presentation Transcript

  • 1. MetabolismCatabolism-Glycolysis (Kreb Cycle) Anabolism-Photosynthesis
  • 2. Metabolism• Sum of all chemical reactions• Catabolism – Exergonic reaction – Most of energy in ATP –last phosphate bond
  • 3. Metabolism• Anabolism – Consume more energy than produce – Use ATP for energy
  • 4. Enzymes• Biological catalysts• Energy of activation• Specificity• Primary structure• Secondary structure• Tertiary structure• Quaternary structure
  • 5. Components of Enzymes• Apoenzyme-protein only• Cofactor-nonprotein – Trace elements• Coenzyme-organic cofactor – Carriers of electrons etc – NAD+
  • 6. Enzyme-substrate Complex• Active site on enzyme• Transformation in substrate• Products released• Enzyme orients substrate• Lowers energy of activation
  • 7. Denaturation• Structure of enzyme is disrupted• No longer active• Temperature• pH• Substrate concentration – Enzyme becomes saturated
  • 8. Inhibitors• Competitive inhibitors• Noncompetitive inhibitors – Allosteric site
  • 9. Feedback Inhibition• End product inhibition• Series of enzymes –end product
  • 10. Energy Production• Oxidation-reduction reactions• Generation of ATP – Phosphorylation – Used for metabolism, binary fission, endospore formation movement
  • 11. Types of Phosphorylation• Substrate level• Oxidative phosphorylation• Photophosphorylation
  • 12. Carbohydrate Metabolism• Glucose as an example• Two energy processes – Cellular respiration – Fermentation – Glycolysis• Respiration-Krebs cycle & electron transport chain
  • 13. Glucose MetabolismC6H12O6 + 6O2 + 38 ADP +38 P6CO2 + 6H2O + 38 ATP
  • 14. Glycolysis• Summary of glycolysis• 2 molecules of pyruvate (3 C)• Production of 2 NADH & 2H+• Net of 2 ATP• Substrate phosphorylation• Takes place in cytosol of bacteria & eukaryotes• No oxygen is required• Alternate pathways
  • 15. Cellular Respiration• Cellular respiration – Final electron acceptor is inorganic molecule• Two types based on final electron acceptor
  • 16. Aerobic Respiration• Krebs cycle• Mitochondria of eukaryotes-matrix• Cytosol in prokaryotes• Intermediary step- production of acetyl CoA – 2 CO2 & 2 NADH
  • 17. Aerobic Respiration• Acetyl Co enters Krebs cycle• 4 carbons of glucose released as CO2• 6 NADH & 2 FADH2 produced• 2 ATP by substrate phosphorylation
  • 18. Electron Transport Chain• Series of redox reactions• Stepwise release of energy• Oxygen final acceptor of electrons• Inner membrane of mitochondria in eukaryotes• Foldings of plasma membrane or thylakoid infoldings( photosynthesis)• Occurs only in intact membranes
  • 19. Carrier Molecules• Some carry both electrons & protons (H+)• Cytochromes transfer electrons only• Oxygen is last link of chain
  • 20. Chemiosmosis• ATP generation• Proton pumps• Proton motive force• Protein channels with ATP synthases
  • 21. ATP Production• Protons release energy as rush through pore• 3 ATP per NADH• 2 ATP per FADH2• ATP produced via oxidative phosphorylation• Damage to membrane ceases proton movement
  • 22. Anaerobic Respiration• Final electron acceptor is an inorganic molecule other than oxygen• Some use NO3 - ,SO42-• Important in nitrogen and sulfur cycles• ATP varies, less than 38• Only part of Krebs cycle & ETC used
  • 23. Fermentation• Pyruvate converted to organic product• NAD+ regenerated• Doesn’t require oxygen• Does not use Krebs cycle or ETC – Shut down• Organic molecule is final electron acceptor• Produces 2 ATP max
  • 24. Photosynthesis• Conversion of light energy into chemical energy• Anabolism (carbon fixation)-produce sugars from CO2• Two stages
  • 25. Overall Reaction6CO2 + 6H2O + ATPC6H12O6 + 6O2 + ADP + P
  • 26. Light Reactions• Photophosphorylation-production of ATP – Only in photosynthetic cells• Light energy (electromagnetic radiation) absorbed by chlorophylls – Chlorophyll a in plants, algae and cyanobacteria – Located in membranous thylakoids of chloroplasts- plants & algae – Infoldings of plasma membrane of cyanobacteria
  • 27. Light Reactions• Electrons flow through ETC• Electron carrier is NADP+• ATP produced by chemiosmosis
  • 28. Noncyclic Photophosphorylation• Plants, algae, cyanobacteria• 2 photosystems• Produce both ATP via chemiosmosis• Produce NADPH – Used to reduce CO2 in dark reactions – Able to produce sugars
  • 29. Summary• ATP produced by chemiosmosis – Uses energy released in ETC• Oxygen produced from splitting of water – H2O→ 2H+ +2 e + O – Replace electrons lost from chlorophyll• NADPH produced in second photosystem
  • 30. Dark Reactions• Calvin-Benson Cycle• Requires no light• Uses energy from ATP (light reactions) to reduce CO2 to sugars• Carbon fixation
  • 31. Summary• Light H20 CO2 NADP+ Photosystems & ETC ADP+ P Calvin Cycle Chlorophyll a Chemiosmosis ATP NADPH sugars Cellular respiration O2 Organic cpds