Lecture 14 Metabolism and Energy Energy ATP=potential to free energy Enzymes and Energy Some reactions are slow because of an energy barrier Energy barrier: the amount of energy required to start the reaction (activation energy) Reactions depend on Collision Kinetic energy Orientation System can ?fall back? to reactants Enzymes lower the activation energy barrier Enzymes Enzymes are typically globular proteins They greatly increase the rate at which a substrate is converted into product Can increase the rate 12^20 times!! Chymotrypsin: An enzyme that breaks apart protein and releases amino acids so your body can absorb them Without it, it would take so long to digest food that we would starve! Catalase: an enzyme found in our cells Protects cells from hydrogen peroxide release in cells Does this by converting hydrogen peroxide into oxygen and water Biological catalysts are highly specific for the substrates that bind to their active sites Enzyme-substrate complex is binded by Hydrogen bonds Electrical attraction Covalent bonds Enzymes orient substrate molecules, bringing together the atoms that will bond They stretch the bonds in substrate molecules, making the ?bonds? unstable, but stabilizing the substrate transition state Active sites ?fit? into substrates An induced fit helps the two molecules form together better and thus catalyze the reaction faster Reaction rates are concentration dependent The concentration of a substrate is usually much greater than that of an enzyme
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