Biological Reactions are Regulated by Enzymes

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  • Created by: Ellen122
  • Created on: 15-03-21 10:12
Enzymes
Biological catalysts
Speed up metabolic reactions both inside and outside cells
Globular proteins with at least a 3 degrees level of structure
Complex 3D shape as the folded polypeptide chain(s) is/are held in place by hydrogen bonds, disulphide bridges,
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Shape of Enzymes
Possess an active site into whicch the substrate molecule fits
Induced Fit - as the substrate fits into active site the shape of the actie site changes slightly to select the substrate molecule
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Induced Fit Example
Peptidoglycan molecules in bacterial cell walls are broken down as they fit into the active site of the enzyme lysozyme found in tears and saliva
Formation of the enzyme substrate complex lowers the activation energy needed for the reaction to proceed
Sha
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Enzyme Reaction
Formation of the enzyme substrate complex lowers the activation energy and increases the rate of reaction
Enzyme is unchanged by the reaction
The active site of the enzyme is unoccupied it can bind with another substrate molecule to form another enzyme su
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Temperature
Increasing temperature increase the kinetic energy of the substrate and enzyme molecule
More successful collisions between enzyme and substrate and an increased rate of reaction
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Denature
High temperatures will lower the rate of reaction
Increased vibrations of the molecules break the hydrogen bonds holding the 3D shape of the enzyme together
Substrate no longer fits into the active site of an enzyme
Denatured
Used in control experiments
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pH
Affect the hydrogen bonds holding the 3D shape fo the enzymes together as hydrogen and hydroxyl ions bind to the amino acids of the enzyme
Affect the shape of the active siteand how well the enzyme can catalyse the reaction
Different enzymes have differen
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Substrate Concentration
As substrate concentration increases there will be more successful collisions between enzyme and substrate
When all available acitve sites are occupied there will be no further increase in rate of reaction
Increases chance of successful collisions
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Enzzyme Concentration
Increasing the enzyme concentration will increase the number of successful collisions between enzyme and substrate and therefore the rate of reactions
Increase probability of a successful collision
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Enzyme Inhibition
Certain substances will slow down or stop enzyme action
Inhibitors combine with the enzyme and prevent it from forming enzyme substrate complexes
Both inhibitors can be reversed if the inhibitor only binds temporarily to the enzyme
Inhibitors that bind pe
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Competitive Inhibitors
Similar shape to the substrate and block the substrate from fitting into the active site
Increasing substrate concentraion wiill reduce the amount of inhibition as there is an increased chance of a collision between the ezyme and the substrate
Malonic aci
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Non-competitive Inhibitors
Bind to the allosteric site
Alter the shape of the active site so that the substrate can no longer fit
Changing the substrate concentration will have no effect on the rate of reaction as enzyme substrate complexes cannot be formed
Cynaide is a non-competi
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Immobilised Enzymes
Enzymes are sometimes immobilised by fixing them to an inert matrix such as alginate beads or cellulose
Beads containing the immobilised enzyme can be packed into columns
Substrate is added to the top of the column and as it flows down it reacts with the
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Advantage of Immobilised Enzymes
Enzyme does not need to be separated from the product
Easily recovered after use to reduce cost
More stab;e and can tolerate a wider range of temperature and pH allowing reactions to be faster as higher temperatures can be used
Several enzymes can be used
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Biosensors
Immobilised enzymes
Detect concentrations of specific biological molecules such as glucose
Used by diabetics to detect blood glucose levels
Glucose binds to the immobilised enzymes and a product is formed
Causes the transducer to produce a small electric
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Other cards in this set

Card 2

Front

Shape of Enzymes

Back

Possess an active site into whicch the substrate molecule fits
Induced Fit - as the substrate fits into active site the shape of the actie site changes slightly to select the substrate molecule

Card 3

Front

Induced Fit Example

Back

Preview of the front of card 3

Card 4

Front

Enzyme Reaction

Back

Preview of the front of card 4

Card 5

Front

Temperature

Back

Preview of the front of card 5
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