Energy and Enzymes: Cellular Respiration Basics - PDF

ENERGY & ENZYMES ENERGY - CAPACITY TO DO WORK KINETIC ENERGY - ENERGY OF MOTION POTENTIAL ENERGY - STORED ENERGY OWING TO ITS LOCATION OR ARRANGEMENT (EX. CHEMICAL ENERGY) IT CAN BE CONVERTED/TRANSFERRED/TRANSFORMED PE  KE THAT CONVERSION IS NEVER...

ENERGY & ENZYMES ENERGY - CAPACITY TO DO WORK KINETIC ENERGY - ENERGY OF MOTION POTENTIAL ENERGY - STORED ENERGY OWING TO ITS LOCATION OR ARRANGEMENT (EX. CHEMICAL ENERGY) IT CAN BE CONVERTED/TRANSFERRED/TRANSFORMED PE  KE THAT CONVERSION IS NEVER 100% EFFICIENT -> HEAT THERMODYNAMICS – STUDY OF ENERGY TRANSFORMATIONS THAT OCCUR IN A COLLECTION OF MATTER (SYSTEM) THE 1ST LAW ENERGY IS CONSERVED. IT CAN BE TRANFERRED OR TRANSFORMED, BUT IS NOT DESTROYED - Principle of the Conservation of Energy THE 2ND LAW EVERY ENERGY TRANSFER OF TRANSFORMATION INCREASES THE DISORDER (ENTROPY) OF THE UNIVERSE. IF THERE IS A GENERAL TENDENCY TOWARD DISORDER, THAN HOW DO LIVING ORGANISMS MAKE THIS? FREE ENERGY - PORTION OF A SYSTEMS ENERGY THAT IS AVAILABLE TO DO WORK THE FORMULA FOR (GIBBS) FREE ENERGY G IS: G=H–TS H – ENTHALPY OR TOTAL ENERGY IN A SYSTEM T – TEMPERATURE (MEASURE OF KINETIC ENERGY) S – ENTROPY (MEASURE OF THE DISORDER) SO WHAT IS THE GENERAL RELATIONSHIP BETWEEN FREE ENERGY AND DISORDER? as entropy goes up, what happens to the amount of energy that can do work? WITH THIS GENERAL TENDENCY TOWARD DISORDER, LIFE GOES DOWNHILL THERE IS AN OVERALL TENDENCY TO MOVE TO A LOWER ENERGY STATE WHICH IS MORE STABLE. SO WHEN WE LOOK AT A TRANSFER OR TRANSFORMATION OF ENERGY, WE CAN TRACK THE CHANGE IN FREE ENERGY DG= DH–TDS IF D G IS NEGATIVE, THE FREE ENERGY IS DECREASED - ENERGY IS RELEASED - EXERGONIC - SPONTANEOUS I SAID EARLIER THIS QUARTER, THAT THERE IS POTENTIAL ENERGY IN A CONCENTRATION GRADIENT, IT IS RELEASED BY DIFFUSION WHICH IS A SPONTANEOUS REACTION. LOOKING AT THIS FORMULA, WHY SHOULD DIFFUSION HAVE A -DG? THE POTENTIAL ENERGY IN A CONCENTRATION GRADIENT CAN BE RELEASED, BUT THAT ENERGY CAN ALSO BE TRANSFERRED. HOW DID THE INTESTINE CELLS MANAGE TO BRING GLUCOSE IN FROM THE INTESTINAL LUMEN EVEN THOUGH THE CONCENTRATION OF GLUCOSE IS MUCH HIGHER IN THE CELLS THAN IN THE LUMEN DO YOU THINK THE OVERALL D G FOR THIS PROCESS IS POSITIVE OR NEGATIVE? WE TALKED ABOUT HOW THE CELL MOVED BOTH Na+ AND K+ UP THEIR CONCENTRATION GRADIENTS ACROSS THE MEMBRANE. THESE PROCESSES REQUIRE ENERGY AND SO - THEY HAVE A +DG - ENDERGONIC HOW WAS THE CELL ABLE TO DO THAT? DO YOU THINK THE OVERALL D G FOR THIS PROCESS IS POSITIVE OR NEGATIVE? LETS TAKE A LOOK AT A COUPLE OF REACTIONS THAT WE WILL BE DISCUSSING OVER THE NEXT WEEK OR SO: GLUCOSE + 6 O2 -> 6 CO2 + 6 H2O DG = - 686 kcal/mole EXERGONIC OR ENDERGONIC? HOW ABOUT THE REVERSE REACTION: 6 CO2 + 6 H2O -> GLUCOSE + 6 O2 WHAT IS IT’S DG? HOW CAN CELLS AFFORD TO RUN THIS REACTION? CELLULAR RESPIRATION HAS A REALLY HIGH -DG. WHY DOESN’T ALL OF THE SUGAR IN YOUR CELLS SPONTANEOUSLY BREAKDOWN TO RELEASE ENERGY? WHAT WOULD HAPPEN IF IT DID? ACTIVATION ENERGY EVEN THOUGH THE RXN HAS A –DG, IT REQUIRES ENERGY TO REACH A TRANSITION STATE IN THE RXN. ENZYMES ARE REQUIRED TO CATLAYSE THE RXNS Enzymes lower the Activation Energy required for the rxn. They do not affect the overall DG for the rxn Enzymes can do this by: 1)Holding substrates in proximity or proper orientation 2)Straining and distorting bonds 3)Providing the suitable local environment for the rxn 4)Acting through transient covalent bonds as part of an intermediate  ENZYME CYCLE Specific binding to active site ng can temporarily changes enzyme structure – induce Enzyme unchanged at the end of catalytic cycle  Specific binding relies upon the chemical characteristics and positioning of R-groups of the amino- acids at the active site Factors that can affect the rate of an enzyme catalyzed rxn: 1)Substrate concentration Rate of RXN Substrate concentration Factors that can affect the rate of an enzyme catalyzed rxn: 2) Temperature 3) pH 4) Coenzymes – additional molecules/atoms fxn as part of the enzyme ex. Magnesium is required for cofactor for chlorophyll fxn ex. Iron for hemoglobin fxn we will see two cofactors NADH and FADH2 fxn as necessary coenzymes in respiration Other molecules can act as regulators to affect the functioning of the enzyme INHIBITORS 2 Types: Competitive Inhibitor Non-competitive Inhibitor How can you experimentally distinguish between the two types?  How can you experimentally distinguish between the two types of inhibitors A B Rate of Rate of RXN RXN Substrate concentration Substrate concentration Blue line is without inhibitor Red line is in the presence of the inhibitor Allosteric Regulation of Enzymes – multi- subunit enzymes FEEDBACK INHIBITION