Energy Chemical Reactions and Enzymes

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

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

Chemical Reactions H2CO3 H2O CO2 reactants elements or compounds that enter into a chemical reaction  products elements or compounds produced by the chemical reaction H2CO3 H2O CO2 + carbon dioxide plus water forms carbonic acid

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

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

Energy in Reactions

Energy in Reactions

Energy in Reactions 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

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

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

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

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

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 + water oxygen catalase

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

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