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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
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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 • Sugar has more energy in the bonds than CO2 + H2O
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