Understanding Enzymes have an active site to which specific substrates bind Enzyme catalysis involves molecular motion and the collision of substrates with the active site Temperature pH and substrate concentration affect the rate of activity of enzymes ID: 260596
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2.5 Enzymes
Understanding:Enzymes have an active site to which specific substrates bindEnzyme catalysis involves molecular motion and the collision of substrates with the active siteTemperature, pH and substrate concentration affect the rate of activity of enzymesEnzymes can be denaturedImmobilized enzymes are widely using in industry
Applications:Methods of production of lactose-free milk and its advantages
Skills:Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymesExperimental investigation of a factor affecting enzyme activity
Nature of science:
Experimental design: accurate quantitative measurements in enzymes experiments require replicates to ensure reliabilitySlide2
Enzyme structure
Proteins that work as a catalyst.Speed up chemical reactions without being altered themselves.
Understanding:Enzymes have an active site to which specific substrates bindSlide3Slide4
Enzyme structure
Enzymes only catalyze one reaction Thousands of reactions take place in a cell Majority need to be catalyzed. Organisms produce thousands of enzymes
Enzymes are specific
Understanding:Enzymes have an active site to which specific substrates bindSlide5
Specificity
Enzymes have an active siteSpecific to a substrateOnly that substrate can fitCannot catalyse other reactions
Understanding:
Enzymes have an active site to which specific substrates bindSlide6
Three Stages
Substrate binds to active site of enzyme.2. Substrates change into different chemical substances3. These products separate from the active site, leaving it vacant for substrates to bind again
Understanding:Enzyme catalysis involves molecular motion and the collision of substrates with the active siteSlide7
Collisions
Random movement of substrates and enzymesMeans there are collisionsOnly bind together if they are aligned exactlyDissolving in water allows more collisions
Understanding:
Enzyme catalysis involves molecular motion and the collision of substrates with the active siteSlide8
Denaturation
Structure can be irreversibly altered by certain conditions.Active site shape changes – substrate can no longer bind
Understanding:Enzymes can be denaturedSlide9
Your Experiment (Wednesday)
Understanding:
Temperature, pH and substrate concentration affect the rate of activity of enzymesEach of you will be investigating one of the following factors affecting the rate of reaction of enzymes. Temperature pHConcentration of substrate
You need to plan and carry out this experiment (each group has a different variable)You will then present your resultsSkills:
Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes
Experimental investigation of a factor affecting enzyme activitySlide10
Equipment available to you
Catalase enzyme (yeast)1% Hydrogen peroxide solution (substrate)Buffer solutions (pH 1, pH7, pH 13)Stop watch
Ice bathWater baths - 30, 40, 50 degrees celsiusThermometerGas syringeConical flask BungDelivery tubeSlide11
Rate of Reaction
How much of a product is formed OR how much a reactant is used upMany things affect the rate of reaction.High rate of reaction = fast reactionLow rate of reaction = low rateSlide12
Rate of Reaction
Measure the mass of a substance (usually start and end – hard to find mid points)Volume of gas measured with a gas syringe or measuring cylinder – can find mid pointsRate of reaction = Amount of product formed OR reactant used Time takenSlide13
Example
If 24 cm3 of hydrogen gas is produced in 2 minutes what is the mean rate of reaction?Slide14
Example
If 24 cm3 of hydrogen gas is produced in 2 minutes what is the mean rate of reaction?24/2 = 12cm3 hydrogen/minSlide15Slide16Slide17Slide18
Immobilised Enzymes
Understanding:
Immobilized enzymes are widely using in industryAttach enzymes to another materialEnzyme movement is restrictedWhat are the advantages?Slide19
Commercially Used
Understanding:
Immobilized enzymes are widely using in industrySlide20
Immobilised Enzymes
Understanding:
Immobilized enzymes are widely using in industryLess likely to denatureCan be re-used again and again Do not contaminate end productDo not need to filter end productCan stop and start the reaction quicklyBut…
Requires extra time & money to make them Extra equipment to make themReduction in reaction rate as there will be fewer collisions