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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

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

11. 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

12. 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