Chemical Reactions and Enzymes

Objectives: 1. To describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction 2. To explain how factors such as pH, temperature, and concentration levels can affect enzyme function

Chemistry is not just what life is made up of, but it is also what life _____ A process that changes or transforms one set of chemicals into another When chemical reactions occur, bonds between atoms are formed or broken, causing substances to combine and recombine as different substances does What is a chemical reaction? Does melting ice produce a chemical reaction? NO Does Alka-Seltzer in water produce a chemical reaction? YES Does baking soda in vinegar produce a chemical reaction? YES So, what is a chemical reaction?

Chemical Reactions Chemical Reactions Some reactions occur slowly, such as _____________ to form ____ Other reactions occur quickly iron and oxygenrust

Chemical Reactions Chemical reactions are represented by writing ________ _________ chemicalequations Chemical equation for water: 2H 2 + O 2 2H 2 O reactantreactant product HydrogenOxygenWater # of molecules # of atoms XXXX

Energy in Reactions Chemical reactions that _______ energy often occur on their own, or ___________ (exergonic) Chemical reactions that ______ energy will not occur without a source of energy (endergonic) All living things ______ and ___ energy Not all exothermic reactions occur spontaneously. Sometimes energy is needed to start a reaction. The energy needed to get a reaction started is known as _________ ______ release spontaneously absorb obtainuse activationenergy

Energy in Reactions Energy releasing reactionEnergy absorbing reaction Exergonic (exothermic) Endergonic (endothermic)

Enzymes What are enzymes? What is a catalyst? Enzymes ________ chemical reactions that take place in cells Proteins that act as biological catalysts A substance that speeds up the rate of a chemical reaction speed up

Enzymes activity in a reaction Enzymes _____ activation energy, which affects how quickly a reaction is completed. Each enzymes is specific to a chemical reaction, generally catalyzing ____ type of chemical reaction Typically it gets its name from the reaction it ________ -ends in ‘ase’ lower one catalyzes Click graph to view video clip

How do enzymes do their jobs? Enzymes provide a site called the ______ _____ where reactants are brought to form a product The reactants are known as __________ in an enzyme-catalyzed reaction Active sites and substrates have complementary shapes and fit together like a _____ and ____ activesite substrates lockkey ____________,____ and regulatory molecules can affect enzyme activity temperaturepH Click graphic to view video clip