1 / 28

Introduction to Metabolism

Introduction to Metabolism. I. The Flow of Energy A. Laws of Thermodynamics. 1. First Law -energy can be transferred or transformed, but not created or destroyed. I. The Flow of Energy A. Laws of Thermodynamics. 2. Second Law

dawson
Télécharger la présentation

Introduction to 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. Introduction to Metabolism

  2. I. The Flow of Energy A. Laws of Thermodynamics 1. First Law -energy can be transferred or transformed, but not created or destroyed

  3. I. The Flow of Energy A. Laws of Thermodynamics 2. Second Law -predicts the direction of all energy exchanges -every energy change increases the Entropy of the universe OR -in every energy change, potential energy decreases

  4. I. The Flow of Energy A. Laws of Thermodynamics 2. Second Law a. Organisms and the Second Law -Living things are Ordered but the Universe is increasing in Disorder? 1) Open System vs Closed Systems -Open: energy/matter exchanged with surroundings -Closed: isolated from surroundings (Universe) 2) Organisms are Open Systems -take in ordered energy; release disordered -increasing Entropy => second law

  5. I. The Flow of Energy B. Spontaneous Change/Reactions and Free Energy 1. Spontaneous Change/Reaction -occurs without outside help a. Reactants -unstable/ordered (low entropy) -high energy b. Products -stable/disordered (high entropy) -less energy (exergonic)

  6. I. The Flow of Energy B. Spontaneous Change/Reactions and Free Energy 2. Free Energy – energy available to do work -indicator of spontaneous change/reactions -involves changes in heat and entropy ΔG = ΔH - TΔS - ΔG < 0 in spontaneous change

  7. I. The Flow of Energy B. Spontaneous Change/Reactions and Free Energy 3. Free Energy and Equilibrium -reactions are reversible a. Equilibrium -products = reactants -“Energy Valley” - ΔG = 0

  8. I. The Flow of Energy B. Spontaneous Change/Reactions and Free Energy 4. Free Energy and Metabolism a. Exergonic Reactions -free energy released -spontaneous -cell respiration b. Endergonic Reactions -free energy is absorbed -nonspontaneous -photosynthesis

  9. I. The Flow of Energy B. Spontaneous Change/Reactions and Free Energy 4. Free Energy and Metabolism c. Metabolic Disequilibrium -Cell at equilibrium (ΔG = 0) = Death -Cells maintain Disequilibrium -Open Systems -Energy Flows in and out

  10. II. Metabolism -sum of all chemical reactions occurring in living systems A. Metabolic Pathways -groups of ordered reactions 1. Catabolic Pathways -breakdown substances -release free energy(Exergonic) -cell respiration 2. Anabolic Pathways -synthesis -photo, protein synthesis -free energy absorbed (Endergonic)

  11. III. ATP (Adenosine Triphosphate) -“energy currency” A. Structure -similar to RNA Nucleotide -Adenine plus 2 phosphate groups

  12. III. ATP (Adenosine Triphosphate) -“energy currency” B. Hydrolysis of ATP -terminal phosphate bond broken => energy released -ATP => ADP + Pi + Energy - ΔG = -13kcal/mole

  13. III. ATP (Adenosine Triphosphate) -“energy currency” C. Energy Coupling by ATP -ATP couples Exergonic process to a Endergonic process 1. Phosphorylation -hydrolysis of ATP; enzymes transfer P group to another molecule => “Phosphorylated Intermediate” -less stable -more free energy -molecule can now do work

  14. III. ATP (Adenosine Triphosphate) -“energy currency” D. The ATP Cycle – Regeneration of ATP - ADP is phosphorylated => ATP - hydrolysis of ATP => ADP + Pi + Energy

  15. IV. Enzymes A. Characteristics -catalysts – speed up reactions without being used up -globular proteins

  16. IV. Enzymes B. Free Energy of Activation -reactions require breaking of bonds in reactants -absorb energy (usually heat) from surroundings; makes bonds unstable 1. Activation Energy (EA) -energy needed to break bonds in reactants; start reaction -makes bonds unstable => Transition State -inc. Free Energy of reactants

  17. IV. Enzymes B. Free Energy of Activation 2. Significance of the Activation Energy Barrier -prevents cellular molecules from breaking down spontaneously -typical cell temps prevent reaching transition state (barrier) -However, EA barrier must be overcome for reactions to take place -Heat will cause denaturing – damage cells -Enzymes lower EA w/out raising temps. -Do Not affect ΔG

  18. IV. Enzymes C. Enzyme Functioning 1. Substrate Specific -due to shape of active site 2. Induced Fit Model -substrate enters active site – weakly bonds -bonding causes enzyme to “clasp” around substrate

  19. IV. Enzymes D. Effect of pH and Temperature 1. Temp affects molecular motion -high temps denature enzyme -30oC -40oC in humans 2. pH -optimum for different enzymes

  20. IV. Enzymes E. Cofactors -nonprotein “helpers” -may bind to active site or to substrate -many are inorganic (zinc, Fe, Cu) -Coenzymes: organic cofactors -vitamins

  21. IV. Enzymes F. Enzyme Inhibitors -reversible (weak bonds) or irreversible (covalent) 1. Competitive Inhibitors -compete with substrate for active site -reverisble -overcome by increasing conc. of substrate 2. Noncompetitive Inhibitors -bind to location other than active site -changes shape of active site -ex. DDT, penicillin

  22. V. Control of Metabolism -control of enzyme activity and location A. Allosteric Regulation 1. Allosteric Sites -receptor site on enzyme for binding of regulatory molecules -binding may inhibit or stimulate enzyme

  23. V. Control of Metabolism -control of enzyme activity and location A. Allosteric Regulation 2. Allosteric Enzymes -two or more polypeptides => enzyme complex -oscillates between active and inactive forms a. Allosteric Activator -stabilizes active form b. Allosteric Inhibitor -stabilizes inactive form

  24. V. Control of Metabolism B. Feedback Inhibition -switching off of metabolic pathway by its end product -end product acts as inhibitor somewhere in pathway

  25. V. Control of Metabolism C. Cooperativity -similar to allosteric enzymes -enzymes with multiple active sites -binding of substrate in one active site makes functional allothers

More Related