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Energy Chemical Reactions and Enzymes

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Energy the ability to move or change matter found in many forms can be converted from one form into another

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Chemical Reactions process that changes one set of chemicals into another always involves changes in the chemical bonds that join the atoms in the compounds

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Chemical Reactions reactants elements or compounds that enter into a chemical reaction products elements or compounds produced by the chemical reaction H 2 CO 3 H2OH2OCO 2 + carbon dioxide plus water forms carbonic acid

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Energy in Reactions Some chemical reactions release energy and others absorb energy. Energy changes are an important factor in determining whether a reaction will occur C A + B + Energy A + B + Energy C

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Energy in Reactions Label each of the following reactions as either: Energy-Releasing Reaction or Energy-Absorbing Reaction (from Holt Biology, pg. 39)

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Energy in Reactions

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activation energy energy needed to start a chemical reaction ex: spark plug in an engine Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants

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Enzymes substances that increase the speed of chemical reactions most enzymes are proteins do not get used up in a chemical reaction

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Enzymes work only within a certain set of conditions enzymes are biological catalysts catalysts substances that reduce the activation energy of a chemical reaction

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Enzymes & Activation Energy Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reaction pathway with enzyme Reactants Products

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Enzyme Specificity substrate substance on which an enzyme acts during a chemical reaction substrate = reactants enzymes act only on specific substrates

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Enzyme Specificity Example: catalase enzyme that breaks down hydrogen peroxide Why is catalase written above the arrow and not included in the reaction? hydrogen peroxide +wateroxygen catalase

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Enzyme Specificity active sites the site on an enzyme that attaches to a substrate enzymes are specific because only its substrate fits into its active site

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Enzyme Characteristics How Enzymes Work McGraw - Hill Hydrolysis of sucrose McGraw - Hill