1. Enzymes Make sure you revise: What Enzymes are Enzymes structure
Factors affecting enzyme action
Enzymes in digestion
Making use of enzymes
Enzymes in industry

2. Enzymes and their structure+ + ↔ ↔
enzyme
reactant +
enzyme-reactant complex ↔
products
Enzymes are biological catalysts – they speed up reactions in living things.
Enzymes are protein molecules made up of long chains of amino acids.
These long chains are folded to produce a special shape enabling other molecules (substrate) to fit into the enzyme (active site).

3. Factors affecting enzyme action
denatured
normal
heat pH
The shape of the enzyme is vital to its function.
The main factors affecting enzyme action are 1.) temperature and 2.) pH
1.) High temperatures can destroy the enzymes ‘special shape’ so it becomes denatured.
2.) Different enzymes work best at different pH values.

4. Enzymes in digestion Enzyme: Amylase Protease Lipase Produced in:
- Salivary glands
- Pancreas
- Small intestine
Stomach
Pancreas
Small intestine
Job:
Catalyses the breakdown of starch into sugars
Catalyses the breakdown of proteins into amino acids
Catalyses the breakdown of lipids (fats and oils) into fatty acids and glycerol
Where:
- Mouth
Also:
1.) The stomach produces hydrochloric acid.
Enzymes in the stomach work best in acidic conditions
2.) The liver produces bile which is stored in the gall
bladder before being released into the small intestine.
Bile neutralises the acid that was added to food in the
stomach. This provides alkaline conditions in which
enzymes in the small intestine work best at.

5. Making use of enzymes

6. Enzymes in industry Type of enzyme Proteases Carbohydrases Isomerases
Use
To ‘pre-digest’ protein in baby foods
To turn starch into sugar syrup for making chocolates and cakes
To turn glucose syrup into fructose syrup to use in slimming foods
Why is it used?
The baby may not be able to digest all the protein itself
Sugar syrup is sweet and makes the food ‘taste nice’
Fructose is twice as sweet as glucose so it can be used in smaller amounts in slimming foods