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CH.6 OVERVIEW

CH.6 OVERVIEW. AN INTRODUCTION TO METABOLISM. I. METABOLISM, ENERGY AND LIFE. THE CHEMISTRY OF LIFE IS ORGANIZED INTO METABOLIC PATHWAYS METABOLISM : THE COLLECTION OF CHEMICAL REACTIONS THAT OCCUR IN AN ORGANISM METABOLISM IS AIDED BY ENZYMES CATABOLIC: BREAKDOWN, RELEASE OF ENERGY

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CH.6 OVERVIEW

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  1. CH.6 OVERVIEW AN INTRODUCTION TO METABOLISM

  2. I. METABOLISM, ENERGY AND LIFE • THE CHEMISTRY OF LIFE IS ORGANIZED INTO METABOLIC PATHWAYS • METABOLISM: THE COLLECTION OF CHEMICAL REACTIONS THAT OCCUR IN AN ORGANISM • METABOLISM IS AIDED BY ENZYMES • CATABOLIC: BREAKDOWN, RELEASE OF ENERGY • ANABOLIC: BUILD-UP, CONSUMPTION OF ENERGY

  3. FIGURE 6.1 THE COMPLEXITY OF METABOLISM (METABOLIC REACTIONS W/IN A CELL)

  4. ENERGY : THE CAPACITY TO DO WORK KINETIC: ENERGY OF MOTION POTENTIAL: ENERGY AT STANDSTILL IN RELATION TO POSSIBLE MOTION B. ORGANISMS TRANSFORM ENERGY

  5. C. THE ENERGY TRANSFORMATIONS OF LIFE ARE SUBJECT TO TWO LAWS OF THERMODYNAMICS • 1ST LAW: ENERGY CANNOT BE CREATED NOR DESTROYED • 2ND LAW: ENERGY CHANGES FORM (CHANGE IN ENTROPY)

  6.  D. ATP POWERS CELLULAR WORK BY COUPLING EXERGONIC TO ENDERGONIC REACTIONS • ATP: THE CELL’S ENERGY SHUTTLE • HYDROLYSIS OF ONE OF ITS PHOSPHATE BONDS RELEASES ADP, INORGANIC PHOSPHATE, AND FREE ENERGY • ATP DRIVES ENDERGONIC REACTIONS BY TRANSFER OF THE PHOSPHATE GROUP TO SPECIFIC REACTANTS, MAKING THEM MORE REACTIVE • THEREFORE, CELLS CAN CARRY OUT WORK, SUCH AS MOVEMENT AND ANABOLISM • CATABOLIC PATHWAYS, DRIVE THE REGENERATION OF ATP FROM ADP AND PHOSPHATE

  7. FIGURE 6.8 THE ATP CYCLE

  8. II. ENZYMES • A.ENZYMES SPEED UP METABOLIC REACTIONS BY LOWERING ENERGY BARRIERS • * ENZYMES: PROTEINS THAT SERVE AS BIOLOGICAL CATALYSTS • - SPEED REACTIONS BY LOWERING ACTIVATION • ENERGY

  9. FIGURE 6.9 AN ENERGY PROFILE OF A REACTION

  10. 6.9 ENZYMES LOWER THE BARRIER OF ACTIVATION ENERGY

  11. B. ENZYMES ARE SUBSTRATE-SPECIFIC • EACH TYPE OF ENZYME HAS A UNIQUE ACTIVE SITE THAT COMBINES SPECIFICALLY WITH ITS SUBSTRATE • SUBSTRATE: THE REACTANT MOLECULE ON WHICH AN ENZYME ACTS UPON • MECHANISM (INDUCED FIT): THE ENZYME CHANGES SHAPE SLIGHTLY WHEN IT BINDS THE SUBSTRATE

  12. THE ACTIVE SITE CAN LOWER ACTIVATION ENERGY BY ORIENTING SUBSTRATES CORRECTLY, STRAINING THEIR BONDS, AND PROVIDING A SUITABLE MICRO-ENVIRONMENT A.THE ACTIVE SITE IS AN ENZYME’S CATALYTIC CENTER

  13. AS PROTEINS, ENZYMES ARE SENSITIVE TO CONDITIONS THAT INFLUENCE THEIR 3-D STRUCTURE EACH ENZYME HAS AN OPTIMAL TEMPERATURE AND PH A.A CELL’S PHYSICAL AND CHEMICAL ENVIRONMENT AFFECTS ENZYME ACTIVITY

  14. NOT ALL ENZYMES FUNCTION ALONE: • COFACTORS: IONS OR MOLECULES FOR SOME ENZYMES TO FUNCTION PROPERLY • COENZYMES: ORGANIC COFACTORS • INHIBITORS: REDUCE ENZYME FUNCTION • COMPETITIVE: COMPETES AND BINDS TO ACTIVE SITE • NONCOMPETITIVE: BINDS TO A DIFFERENT SITE, BUT STILL INHIBITS

  15. FIGURE 6.14 ENZYME INHIBITION

  16. III. THE CONTROL OF METABOLISM A.METABOLIC CONTROL OFTEN DEPENDS ON ALLOSTERIC REGULATION • * SOME ENZYMES CHANGE SHAPE, WHEN REGULATORY MOLECULES, EITHER ACTIVATORS OR INHIBITORS, BIND TO SPECIFIC ALLOSTERIC SITES • * ALLOSTERIC SITE: A SPECIFIC RECEPTOR SITE ON AN ENZYME REMOTE FROM THE ACTIVE SITE. MOLECULES BIND TO THE ALLOSTERIC SITE AND CHANGE THE SHAPE OF THE ACTIVE SITE, MAKING IT EITHER MORE OR LESS RECEPTIVE TO THE SUBSTRATE

  17. FIGURE 6.15 ALLOSTERIC REGULATION

  18. FEEDBACK INHIBITION: THE END-PRODUCT OF A METABOLIC PATHWAY ALLOSTERICALLY INHIBITS THE ENZYME FOR AN EARLY STEP IN THE PATHWAY FIGURE 6.16 FEEDBACK INHIBITION

  19. COOPERATIVITY: A SUBSTRATE MOLECULE BINDING TO ONE ACTIVE SITE OF A MULTI-SUBUNIT ENZYME ACTIVATES THE OTHER SUBUNITS 6.17 COOPERATIVITY

  20. SOME ENZYMES ARE GROUPED INTO COMPLEXES, SOME ARE INCORPORATED INTO MEMBRANES, AND OTHERS ARE CONTAINED IN ORGANELLES B. THE LOCATION OF ENZYMES WITHIN A CELL HELPS ORDER METABOLISM

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