1 / 32

Metabolism

Metabolism. Enzymes Metabolism and Metabolic Pathways. Enzymes. Proteins which function as biological catalysts Each biochemical transformation in a cell has a specific enzyme associated with it. Enzymes and Activation Energy. Lock and Key Model.

nerita
Télécharger la présentation

Metabolism

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Metabolism Enzymes Metabolism and Metabolic Pathways

  2. Enzymes • Proteins which function as biological catalysts • Each biochemical transformation in a cell has a specific enzyme associated with it

  3. Enzymes and Activation Energy

  4. Lock and Key Model • Interaction between enzyme and substrate analogous to a lock and key • Active site • Allosteric sites

  5. Kinetics of an Enzymatically Catalyzed Reaction • Conversion of substrate to product • Concentration of substrate and enzyme constant • All experimental conditions (pH, temp) constant

  6. Effect of [S] on V0 • Initial linear relationship between increasing [S] and initial reaction velocity • Saturation kinetics • Overall a hyperbolic curve

  7. Michaelis-Menton Kinetics • Vmax • Maximum reaction rater • KM • Affinity constant • [S] when V0 = 1/2 Vmax • Values can be estimated from hyperbolic graph

  8. Lineweaver - Burke Plots • Linearizes Michaelis-Menton plot • Plot 1/V0 vs 1/[S]

  9. Monod Equation

  10. Metabolism

  11. Definitions • Metabolism: The sum of the biochemical reactions which occur in a cell • Pathway: • A series of connected reactions • A --> B--> C-->D-->E • Catabolism: • Breakdown complex substrates • Generally oxidations

  12. Energy yielding • Generate reduced electron carriers • Anabolism • Build up complex molecules from precursors • Generally reductions • Energy requiring • Oxidize electron carriers

  13. ATP and Energy Transfer • ATP <---> ADP <---> AMP • High energy (squiggle) phosphate bonds • 7.3 kcal to make or break these bonds • Transfer energy from energy yielding reactions to energy requiring reactions

  14. Mechanisms of Energy Generation • Substrate level phosphorylation • Oxidative phosphorylation • Photophosphorylation

  15. Electron Carriers • Coenzymes • NAD/NADH + H+ • FAD/FADH2 • Transfer electrons from oxidation to reduction reactions • Need for initial electron donor and terminal electron acceptor

  16. NAD/NADH + H+

  17. Understanding Metabolic Pathways • Keep track of: • Elements • Energy (ATP/ADP) • Electrons • Why are there so many steps in the pathways • Energetic constraints • Generation of intermediates

  18. Central Metabolic Pathways • Essential pathways • Found in all organisms • Include: • Glycolysis (EMP) • TCA (Kreb’s) cycle • ETS

  19. Other Pathways • Specific catabolic pathways not found in all organisms • If an organism can convert a compound into an intermediate in Central metabolism, complete mineralization (catabolism to carbon dioxide and water) is possible.

  20. Overview of Pathways

  21. Conversion of glucose to 2 pyruvate Most common pathway for initial metabolism of glucose Anaerobic pathway Substrate level phosphorylation Low energy yield/incomplete oxidation Production of NADH + H+ Glycolysis

  22. Fermentation • Reoxidation of NADH + H+ to NAD • Organic compound functions as a terminal electron acceptor • Important in • Industrial production of chemicals • Food production: bread, wine, etc.

  23. TCA Cycle • Oxidation of pyruvate to carbon dioxide • Low direct energy yield • Generates large amounts of reduced coenzymes • Produces biosynthetic intermediates

  24. Respiration • Transfer of electrons from electron acceptors to terminal electron acceptors • Aerobic organisms: oxygen • Anaerobic organisms: other inorganic compounds • Nitrate • Sulfate • Iron • Carbonate

  25. Electron Transport System • Series of compounds which are alternatively reduced and oxidized • Orientation in the membrane. Net translocation of charge and hydrogen across the membrane

  26. Chemiosmosis • Couples electron transport with ATP generation • Development of transmembrane potential by transfer of electrons and hydrogens • Where H+ reenters the cell, ATP synthease is present

More Related