We couldn’t live with out them! Enzymes Are Important! We couldn’t live with out them!

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

Activation Energy Do this by lowering the ACTIVATION ENERGY - the energy required for a reaction to begin Energy Uncatalysed reaction Catalysed reaction Progress of reaction

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

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

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 OXYGEN AND WATER HPCOW CATALASE

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

More about Specific Enzymes This means amylase will only breakdown starch Catalase will only breakdown hydrogen peroxide Amylase will NOT breakdown hydrogen peroxide Catalase will NOT breakdown starch

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

enzyme substrate complex Model of Lock and Key substrate products enzyme substrate complex active site enzyme enzyme – unchanged

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

Effect of pH Most enzymes have an optimum pH of 7 Some enzymes have a different optimum pH for example pepsin which is used for digestion of proteins in the stomach has an optimum pH of 2