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27 Cards in this Set
- Front
- Back
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metabolic pathway |
aspecific molecule and ends with a product |
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catalyst |
achemical agent that speeds up a reaction without being consumed by the reaction |
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enzyme |
acatalytic protein |
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enzyme-catalyzed reaction |
Hydrolysis of sucrose by the enzymesucrase isan example of |
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a slow process |
The reaction sucrose --> glucose +fructose is normally |
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activation energy |
Theinitial energy needed to start a chemical reaction -oftensupplied in the form of thermal energy that the reactant molecules absorb fromtheir surroundings -whenthe reactant molecules have absorbed enough energy, the bonds become unstable andthe molecule releases the transition state. |
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exergonic |
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lowering the Ea threshold; usinghigh temperature would denature proteins and kill cells or speed up all reactions withinthe cell. |
Enzymescatalyze reactions by what instead of using high temps |
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substrate |
Thereactant that an enzyme acts on is calledthe enzyme’s |
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enzyme-substrate complex |
Theenzyme binds to its substrate, forming an |
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active site |
the region on the enzymewhere the substrate binds; not rigid changes to fit enzyme |
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induced fit |
a substrate brings chemical groupsof the active site into positions that enhance their ability to catalyze thereaction |
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-Orienting substrates correctly -Straining substrate bonds -Providing a favorable microenvironment -Covalently bonding to the substrate (avery brief covalent bond is formed that is removed by subsequent reactions) |
Theactive site can lower an Ea barrier by: |
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-General environmental factors, such astemperature and pH -Chemical influence |
enzyme’sactivity can be affected by |
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-Substrate concentration -enzyme concentration |
The speed of enzyme activity (how efficient it functions) canbe influenced by |
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-pH (human normal pH 6-8) -temperature (35-40C) |
enzymes have optimal |
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cofactors |
non-proteinenzyme helpers |
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-inorganic ex. zinc, copper -organic (coenzyme) ex. vitamins |
Cofactorsmay be |
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competitive inhibitors |
bindto the active siteof an enzyme, competing with the substrate ex. penicillin, sarin nerve gas, and methanol |
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noncompetitive inhibitors |
bindto another part of an enzyme(NOT the active site), causing the enzyme to change shapeand making the active site less effective ex. heavy metal poisoning |
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competitive inhibition |
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noncompetitive inhibition |
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allosteric regulation |
aregulatory molecule binds to a protein at one site andaffects the protein’s function at another site -mayeither inhibit or stimulate an enzyme’s activity |
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activator |
Thebinding of an ______ stabilizes the active form of theenzyme |
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inhibitor |
Thebinding of an ______ stabilizes the inactive form ofthe enzyme |
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cooperativity ex. hemoglobin |
A form of allosteric regulationthat can amplify enzyme activity -onesubstrate molecule primes an enzyme to act on additional substrate moleculesmore readily - allostericbecause binding by a substrate to one active site affects catalysis in adifferent active site |
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feedback inhibition ex. isoleucine synthesis; enzyme threonine |
theend product of a metabolic pathway shuts down the pathway - preventsa cell from wasting chemical resources by synthesizing more product than isneeded |
