CHAPTER 8 NOTES Define all bold italicized words before class You may be chosen at random during lecture to volunteer a definition I METABOLISM TRANSFER OF BOND ENERGY Metabolism totality of all chemical reactions going on in an organism Anabolism building things up start with CO2 and H2O also light glucose all other macromolecules increase in molecule complexity consumes potential energy Catabolism breaking things down starch carbon dioxide and water decrease in molecule complexity releases potential energy cellular respiration sugar glucose and other molecules being broken down in the presence of oxygen to carbon dioxide and water Potential energy stored energy Kinetic energy relative motions of objects any organic compounds broken down always break down to CO2 and H2O all organisms do anabolic processes few do catabolic processes autotrophs Metabolism is the totality of cellular energy management B Transforming energy between forms The study of the energy transformations that occur in a collection of matter is called thermodynamic 1st Law of Thermodynamics energy can t be created nor destroyed energy can be transferred and transformed but it can t be created or destroyed 2nd Law of Thermodynamics increase of entropy randomness every energy transfer or transformation increases the entropy of the universe entropy measure of disorder or randomness energy changing form with increase of entropy you have an increase of heat C Just where is the chemical energy in a Twinkie How did it get there Energy is in the bonds Between C H bonds When you break bonds you release energy stored in electron pairings Bonds can be compared to springs when they are bent bonded they have built up energy and when broken the energy is released Fats store more energy because they have more C H bonds D ATP is a rechargeable battery ATP is an energy storing nucleotide Energy in the phosphate bonds phosphate groups have a lot of negative charges so it has lots of tension strong bent springs so breaking a phosphate bond will give a lot of energy One million molecules of ATP are made per second ATP P P P you break bonds P P P and then you get ADP P P which is an un energized phosphate group add energy and you can recharge ATP ATP H20 ADP organic phosphate HOPO32 The addition of phosphate to ADP will regenerate ATP E Exergonic vs Endergonic Reactions define B 4 class Exergonic Reactions reactions that release energy typically put some energy in to get the reaction started Endergonic Reactions energy required one that absorbs free energy from its surroundings nonspontaneous Efflflflfl II ENZYME CATALYZED CHEMICAL REACTIONS A ATP input is required to initiate exergonic reactions in the cell Changes shape at each state B Enzymes lower Activation Energy Ea accelerating reaction rates activation energy the initial investment of energy for starting a reaction the energy required to contort the reactant molecules so the bonds can break Energy starts at same point different activation energy Enzymes make it easier to reach activation state but they don t change the equilibrium Enzyme s chemical nature What type of macromolecule is an enzyme Protein very specific What is a catalyst Enzymes are catalysts speed up reactions but aren t consumed by reaction Enzymes lower transition energy Tertiary structure and catalytic cycles 1 Specificity What is an active site Where specific substrates fit typically a pocket or groove on the surface of the enzyme where catalysis occurs 2 Catalytic cycle How FAST did you say What physically allows an enzyme to do that Cataylize 1 000 substrate product per second 3 Enzyme saturation If you want product at a faster rate increase enzyme rate related to optimal conditions more enzyme molecules increase substrate ligand concentration A ligand is a molecule that interacts with another protein Put in more ligand and get more product Engaging all enzymes 100 concentration they can t form product any faster because all are working Factors that affect enzyme activity 1 Cofactors molecules that work together with enzymes required in extremely small quantities many enzymes require nonprotein helpers for catalytic activity these are cofactors a inorganic no carbon Fe Zn Cu b organic vitamins If it s missing a cofactor the enzyme doesn t work 2 Effect of temperature and pH related to structure a Optimal temp increase in temperature leads to increase in kinetic energy increase in substrate active site collisions which leads to increased reaction rate if you greatly increase temperature proteins denature b Optimal pH change pH change the shape of protein the protein unravels and doesn t work 3 Enzyme inhibitors decrease enzyme activity a Competitive vs non competitive i Competitive inhibitor tennis ball mimics for the active site looks like substrate can get in the active site but there is no reaction because it isn t the right substrate with increase of the substrate you can overcome inhibition if reversible not covalently bonded ii Noncompetitive inhibitor brush binds some place other than the active site on the enzyme the noncompetitive inhibitor changes the 3D shape of the active site so substrate no longer fits the active site with increase of substrate it won t over come inhibition b Reversible vs Irreversible i Reversible inhibitor binds via weak bonds easily broken ii 4 Irreversible inhibitor binds with covalent bonds Allosterism Changing enzyme activity by modulating enzyme shape with a molecule General term for proteins that have 2 binding sites modulator molecule binds with regulatory site use this energy to turn the enzyme on or off Similar to noncompetitive inhibition 5 Covalent Modification Changing enzyme activity by modulating enzyme shape with a phosphate group instead of you donate a phosphate group III METABOLIC CONTROL OF CELLULAR REACTION PATHWAYS A Feedback inhibition by reaction end products limit reaction rates B Adjusting End Product quantity for market demand 1 Protein synthesis of a specific enzyme 2 C Protein degradation of a specific enzyme Cooperativity facilitates shape modulation of multimeric allosteric enzymes binding 1 Metabolic pathways proceed through several reactions in the conversion of initial substrate to final product Analogous to car assembly line 2 The product for the previous reaction becomes the substrate for the next reaction 3 Each reaction in the pathway requires a different enzyme to recognize a uniquely shaped substrate Lock and key analogy 4 If the