Chemical Reactions And Enzymes

Chemical Reactions Processes that change one set of chemicals into another set of chemicals Reactants  Products (bonds break) (new bonds form)

Energy in Reactions Some reactions release energy -often spontaneously Some reactions absorb energy -need an energy source What significance do these energy changes have for living things?

Activation Energy The energy needed to start a reaction

Enzymes Some reactions are too slow or have activation energies that are too high Catalyst – a substance that speeds up the rate of a chemical reaction

ENZYMES (proteins) act as biological catalysts They speed up chem.rxns. inside cells by lowering the activation energy They are very specific (catalyze 1 rxn.)

Enzyme Action Reactants need enough energy for bonds to break Enzymes provide a site where reactants can be brought together to react (active site) The site reduces the energy needed Substrates -the reactants of enzyme-catalyzed reactions (ex. Hexokinase, pg. 52-53)

Enzyme-Substrate complex

Enzyme Activity Enzymes can be affected by any variable that influences a chemical reaction. Denatured examples: pH, temperature change Enzymes in human cells work best at 37°C (normal body temp.) Lew-port enzymes

Cells have proteins that help turn enzymes on and off Enzymes are important in: -regulating chemical pathways -making materials that cells need -releasing energy -transferring information -forming tissues -fighting disease

Hydrolysis of Gelatin Proteases-enzymes that break down other proteins into smaller polypeptides, amino acids Isolated from strains of Bacillus bacteria -stable at High Temp -can be genetically engineered

Stable at alkaline pH, various temps. Added to laundry detergents Can be genetically engineered

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