C astlehead H igh S chool Enzymes We couldn’t live with out them! Intermediate 2

C astlehead H igh S chool What is an enzyme? Known as a BIOLOGICAL CATALYST Catalyst is something that speeds up a chemical reaction Biological catalyst speeds up reactions in living cells

C astlehead H igh S chool Activation Energy Do this by lowering the ACTIVATION ENERGY - the energy required for a reaction to begin Progress of reaction Energy Uncatalysed reaction Catalysed reaction

C astlehead H igh S chool Properties of Enzymes They are made of PROTEIN They are not changed by the reactions they speed up They are SPECIFIC- means that only one particular enzyme will work with one particular substrate

C astlehead H igh S chool Other terms you need to know Substrate – the substance that the enzyme works on e.g. Amylase the substrate is starch Product – the substance that is made by the reaction e.g. Breakdown of starch by Amylase the product is Maltose

C astlehead H igh S chool CATALASE Found in animal and plant cells Needed to speed up the breakdown of HYDROGEN PEROXIDE Breaks it down to OXYGEN and WATER The word equation for this looks like this HYDROGEN PEROXIDE CATALASE OXYGEN AND WATER HPCOW

C astlehead H igh S chool Amylase Found in saliva and in the pancreas Break down enzyme Breaks STARCH down to MALTOSE Word equation looks like this STARCH MALTOSE AMYLASE SAM

C astlehead H igh S chool Potato Phosphorylase Synthesis enzyme (builds up) Builds Glucose-1-Phosphate molecules into Starch The formation of starch is tested using iodine solution Phosphorylase G1PPS Glucose-1-Phosphate Starch

C astlehead H igh S chool More about Specific This means amylase will only breakdown starch Catalase will only breakdown hydrogen peroxide Amylase will NOT breakdown hydrogen peroxide Catalase will NOT breakdown starch

C astlehead H igh S chool Lock and Key All enzymes have a special shaped area that fits onto their substrate This area is called the ACTIVE SITE This Active site will fit onto the substrate while the reaction takes place Because it fits like a lock and key we call this the lock and key mechanism

C astlehead H igh S chool Model of Lock and Key products substrate enzyme enzyme – unchanged active site enzyme substrate complex

C astlehead H igh S chool Effect of Temperature Speed of reaction increases until an Optimum temperature is reached Optimum temperature is the temperature at which the enzyme works best After this point the rate of reaction decreases until there is no reaction At this point enzyme is said to be DENATURED – active site destroyed

C astlehead H igh S chool Effect of pH Most enzymes have an optimum pH of 7 Some enzymes have a different optimum pH for example pepsin has an optimum pH of 2

C astlehead H igh S chool More to do Click on links to go to website and do Biology keystage 3 lessons 14,15,16,39 and 40 Also go to BBC bitesize standard grade biology topic investigating cells Enzymes and Aerobic Respiration