enzymes and exo endo rxns
TRANSCRIPT
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Enzymes• Enzyme– Catalyst
• Anything that speeds up the rate of a reaction by lowering the ACTIVATION ENERGY– Activ. E: energy required for a chem.
Rxn to start making products– used to regulate the rate (speed) of chemical
reactions– Protein that helps speed up a reaction that occurs
in a biological system– Name of enzymes end in –ASE
• all enzymes are proteins, but not all proteins are enzymes
• each chemical reaction in an organism requires its own specific enzyme
• enzymes are never changed by their reactions!
SubstrateMolecule/compound that attaches to enzyme
Active SiteSpecific location on enzyme for substrate to attachWhere the enzymatic reaction occurs
Enzyme-substrate complexWhen substrate binds to active site of enzyme
Productsmolecules produced at the end of an
enzymatic reaction
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Factors that Effect the Rate of Reactions• Temperature
– Hot• Breaks bonds that give proteins its tertiary structure
DENATURES
– Cold• Slow down chemical reaction (formation of enzyme
substrate complex)
• pH– Acids and bases produce OH- and H+ ions
• too many ions are present, the enzyme may be denatured (twisted and pulled so out of shape that it can no longer function)
• Inhibitors– Non-competitive
• react with portions of the active site, changing of its shape
• Allosteric Inhibitors– Change shape of the enzyme– Attach to regulatory site (not active site) and change the
shape of the entire enzyme (specifically the active site)
– Competitive• look like substrate, bind to active site, but do not make
the intended product
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• Acetylcholinesterase– catalyzes the breakdown of the neurotransmitter
acetylcholine at several types of synapses as well as at the neuromuscular junction — the specialized synapse that triggers the contraction of skeletal muscle.
– One molecule of acetylcholinesterase breaks down 25,000 molecules of acetylcholine each second
– makes possible the rapid "resetting" of the synapse for transmission of another nerve impulse.
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Lock and Key Model
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Examples of endothermic reactions:Melting of ice absorbs energy Dissolving ammonium nitrate in water( the essence of commercial cold packs)
Examples of exothermic reactions:Digestion of food releases energy All combustion reactions (fires) C + O2 CO2 + EAdding an alkali metal to water 2 Na + 2 H2O 2 NaOH + H2 + E
Condensation of water Explosion of bombs
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Endothermic Reactionsthe reactants have less potential energy than do the products. Energy must be input in order to raise the particles up to the higher energy level.Energy + A + B --> AB
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Exothermic Reactionsthe reactants have more potential energy than the products have. The extra energy is released to the surroundings. A + B --> AB + Energy