2 Changing Reaction Rates Certain factors help speed up reactions which normally would take a long time to proceed.An example of this is when Hydrogen Peroxide breaks down to form water and oxygen:2H2O H2O O2When this reaction is heated, the reaction rate (amount of chemical change per unit time) increases!The energy (e.g. Heat) required to make any chemical reaction proceed is called the ACTIVATION ENERGY(Hydrogen Peroxide)(Water)(Oxygen)
3 CatalystsNot only does heat (temperature) effect the reaction rate, but other chemicals also help speed the reactions up.Manganese Dioxide is a chemical which helps the Hydrogen Peroxide reaction proceed faster.A substance which increases the rate of reaction is called a CATALYST.There are also biological (protein) catalysts and these are called ENZYMES!Enzymes are protein molecules which occur naturally in all living cells.Catalase is an enzyme found in liver cells which helps speed up the Hydrogen Peroxide reaction.
4 Properties of an Enzyme: Biological CatalystLowers the energy input/activation energy required for a chemical reaction to proceed.Speeds up rate of reactionEnzymes are proteinsEnzymes remain unchanged after a reaction and therefore can work again.Enzymes are specific to a substrate of a reaction (Lock and Key).Enzymes are reversible and can catalyse a reaction going both ways (Synthesis/Lysis)Enzymes are denatured by:Change in TemperatureChange in pHTherefore have an optimum Temperature and pH, where it works most effectively. In Humans that is usually around 37˚C and a pH of 7.
6 Activation energy with/without Enzymes (Substrates)(Products)
7 ENZYME-SUBSTRATE COMPLEX Specificty of EnzymesLock and Key Mechanism:On Enzyme surface there is the active site which fits specifically with the substrate molecule it is suited to work on.Active SiteActive Site unchanged, can now work on a new substrate.SUBSTRATEENZYME-SUBSTRATE COMPLEXPRODUCTS
8 Degradation of Complex Substrate Degradation/lysis (breaking down) of complex substrate
9 Synthesis of Complex Product Synthesis (building up) of complex product
10 Effect of Amylase Enzyme on starch (Degradation) glucoseglucoseglucoseglucoseglucoseglucoseAmylase EnzymeglucoseglucoseglucoseglucoseMALTOSEglucoseAmylase EnzymeglucoseglucoseglucoseglucoseglucoseAmylase Enzymeglucoseglucoseglucoseglucose
11 Effect of phosphoraylase on Glucose-1-phosphorylase (Synthesis) Glucose-1-PhosphateHow do you test for starch? (Iodine)… so wouldn’t this be a good test to see the effect of PhosphorylasePhosphorylase EnzymeBond forming between two Glc moleculesGlucose-1-PhosphatePhosphorylase EnzymeEct………….STARCH molecule formedPhosphorylase Enzyme
12 The equations for the previous reactions: Effect of amylase (degradation)Starch Maltose (simple sugar)Effect of potato phosphorylase (synthesis)Glucose-1-phosphate Starch(Substrate)(Products)Amylase(Substrate)(Products)Potato Phosphorylase
13 Effect of Temp/pH on Enzyme Activity Optimum Temp/pH for enzyme activity!Rate of Reaction/Enzyme ActivityEnzyme is becoming denatured (the active site is being physically altered (permanent damage)Temp/pH (Arbitary units)