enzymes and exo endo rxns
TRANSCRIPT
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
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
• 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.
Lock and Key Model
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
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
Exothermic Reactionsthe reactants have more potential energy than the products have. The extra energy is released to the surroundings. A + B --> AB + Energy