1. Introduction to Enzymes
IGCSE Combined Science

2. Learning Outcomes Everyone should
-explain why enzymes are necessary for life
-state that enzymes are made of protein
Most people will
-understand that an enzyme is a biological catalyst
Some people might
-be able to write out word equations for enzyme reactions

3. What is a chemical reaction?
It is when a substance reacts and changes in some way

4. ‘Living’ reactions
Reactions that happen inside an organism are part of processes called metabolism. For example:
Respiration
Digestion
Growth
Germination
Photosynthesis
Hydrogen peroxide on its own
Gently warm and see effect
Add manganese dioxide powder and see effect
FRESH LIVER

5. Behold Hina’s Magical Pineapple
What affect has it had on the jelly?
Why do you think this has happened?

6. Important? no reactions? no life!
Almost all chemical reactions in an organism are controlled by enzymes.
Without enzymes these reactions would go too slowly for life to exist.
Most processes in an organism consist of many reactions in sequence.
Each one is catalysed by a specific enzyme- one enzyme for one reaction.
no reactions? no life!

7. Some key words to listen out for:
Catalyst Substrate Product Enzyme Metabolism Active site Specific

8. Enzymes Describing reactions
Enzymes (and catalysts) take part in a reaction but are unchanged at the end of it.
They can be used over and over again but are not used up in the reaction.
Describing reactions
Catalase
Hydrogen peroxide water + oxygen
Enzyme
Substrate
Product
The molecule that an enzyme works on
The molecule that is produced

9. Now you try! Try the practice exercise on your handout
If you finish quickly try the extension!

10. Can you?
-explain why enzymes are necessary for life? -state what enzymes are made of? -understand why an enzyme is a biological catalyst? -write out a word equation for an enzyme reaction?