Enzymes
Transcript of Enzymes
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Enzymes - VIP molecules.
Mr Mark GretgrixWedderburn College
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Description/ DefinitionBiological catalysts, made of
protein, coded for by DNA.allow reactions to occur more
easilyhelp cells perform reactions
that would normally occur very slowly, or not at all
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do not get changed during reaction, they can be recycled
found in cytoplasm and in various organelles
can be secreted and work outside the cell
are involved in breakdown and synthesis
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Examples:
Urease - catalyses the breakdown of urea
Catalase - breakdown of hydrogen peroxide
Polymerase - DNA synthesis
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Cell Metabolism.Refers to all the chemical
reactions in a cell.Involves complex sequences of
reaction with each one controlled by an enzyme. The product of one reaction becomes the reactant of the next reaction.
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By controlling the availability of enzymes, cells can control which chemical reactions will take place at any one time.
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Mode of Operation
Enzymes act to orient the reactant/s so that they behave exactly as required for the reaction to occur.
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Substrate Product
Eg a decomposition reaction:
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Sucrose Glucose + fructose:
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The enzyme has a specific shape, it can only be used to catalyse one type of reaction.
The site at which the reaction takes place in the enzyme is called the ACTIVE SITE.
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Rate of Reaction - depends on:Temperatureamount of reactants and
products presentpHpresence of other
substances
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Temperature:
As temperature increases the number of collisions between molecules increases.
--> increases enzyme activity
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As temperature decreases the number of collisions between molecules decreases.
--> decreases enzyme
activity
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At higher temperatures the protein structure ‘overheats’, the enzyme is ‘denatured’, the active site cannot function. --> decrease in enzyme activity
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Amount Reactants/ Products- enzymes work in equilibrium reactionsEnzymes operate to create a
balance between reactants and products
To increase enzyme activity reactants need to be available and products need to be removed.
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Amount of enzyme present:
An increased amount of enzyme will increase the reaction rate.
This will be affected by the concentration of the substrate available.
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pH
Affects hydrogen bonding in the protein which affects the active site
Each type has its optimal pH, activity decreases away from this value
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Other substancesBlock the active site by binding
to it. eg. poisons
Alter the shape of the active site by binding onto another part of the enzyme
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Co-enzymes
Small molecules needed to help the enzymes in their activity
eg. Some vitamins, trace elements