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Metabolism

Metabolism. Catabolism-Glycolysis (Kreb Cycle) Anabolism-Photosynthesis. Metabolism. Sum of all chemical reactions Catabolism Exergonic reaction Most of energy in ATP –last phosphate bond. Metabolism. Anabolism Consume more energy than produce Use ATP for energy. Enzymes.

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Metabolism

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  1. Metabolism Catabolism-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 Denaturation • Structure of enzyme is disrupted • No longer active • Temperature • pH • Substrate concentration • Enzyme becomes saturated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 Metabolism C6H12O6 + 6O2 + 38 ADP +38 P 6CO2 + 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 • 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 Reaction 6CO2 + 6H2O + ATP C6H12O6 + 6O2 + ADP + P

  26. Light Reactions • Photophosphorylation-production of ATP • Only in photosynthetic cells • Light energy (electromagnetic radiation) absorbed by chlorophylls • Chlorophyll a • 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 Calvin Cycle Photosystems & ETC Chlorophyll a Chemiosmosis NADP+ ADP+ P ATP NADPH Cellular respiration Organic cpds sugars O2

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