Enzymes

Chemical Reactions Energy breaks chemical bonds Energy released (heat & light) Energy stored in new bonds Activation Energy: amount of energy needed to start a reaction

Exothermic Reactions Exo = exit; thermic = heat Defined: Release more energy than it absorbs Light & heat Ex: Cellular Respiration Process that creates energy for cells Chemical energy released for cells… Heat energy released for warmth

Endothermic Reactions Endo = within; thermic heat Defined: Absorb more energy than it releases Ex: Photosynthesis Sunlight has more energy than sugar produced

Enzymes Activation energy usually comes from an increase in temp Slow process Catalyst: substance that decreases the activation energy needed to start a chemical reaction Speeds up reaction Enzymes reduce energy needed (activation energy) to start a chemical reaction

Controlled Settings Human body ~98.6°F Can’t raise body temp to start reactions. Internal reactions would be too slow to sustain life without a catalyst Ex: Saliva Breaks down starch 1,000,000x faster with amylase

Enzyme Structure Enzyme shape allows specific reactants to bind together Reactants = substrate Ex: Amylase & starch: Starch is the substrate because it binds to amylase Substrates binds to activation sites on the enzyme (key fitting into a lock) Once binded to enzyme, substrates bonds weakened Substrates bonds break Substrates re-bond to each other