1. Enzymes
And how they work

2. Enzymes
Enzymes are proteins – they are biological catalysts.

3. Enzymes Enzymes are proteins – they are biological catalysts.
This means they can speed up a reaction that would otherwise take months to occur while the enzyme itself is NOT CHANGED in the process.

4. Enzymes Enzymes are proteins – they are biological catalysts.
This means they can speed up a reaction that would otherwise take months to occur while the enzyme itself is NOT CHANGED in the process.
Enzymes can therefore be used over and over again.

5. Enzymes Enzymes are proteins – they are biological catalysts.
This means they can speed up a reaction that would otherwise take months to occur while the enzyme itself is NOT CHANGED in the process.
Enzymes can therefore be used over and over again.

6. Lock & Key model
Two enzymes of different shapes working together to fit into a reactive site.

7. Lock & Key model
Two enzymes of different shapes working together to fit into a reactive site.
When they fit together, an enzyme-substrate complex is formed and the two chemicals react.

8. Lock & Key model
Two enzymes of different shapes working together to fit into a reactive site.
When they fit together, an enzyme-substrate complex is formed and the two chemicals react joining together.
The enzyme then detaches itself and is ready to catalyse another two chemicals that fit.
** Catalysts must be specific – eg they can only fit together, not to other ones…

9. Induced fit model
Substrate binds to the enzyme, may induce a change in the shape of the enzyme molecules.

10. Induced fit model
Substrate binds to the enzyme, may induce a change in the shape of the enzyme molecules.
The change puts strain on the chemical bonds between the substrate molecules and causes them to react.

11. Induced fit model
Substrate binds to the enzyme, may induce a change in the shape of the enzyme molecules.
The change puts strain on the chemical bonds between the substrate molecules and causes them to react.
When the product is released, the enzyme returns to its original shape.

12. Activation energy barrier
Energy is needed to get the reaction going – this is activation energy barrier.

13. Activation energy barrier
Energy is needed to get the reaction going – this is activation energy barrier.
In a lab, you could use heat to speed up the reaction, but in your body, you can’t heat it up = enzymes.

14. Activation energy barrier
Energy is needed to get the reaction going – this is activation energy barrier.
In a lab, you could use heat to speed up the reaction, but in your body, you can’t heat it up = enzymes.
Enzymes are used to lower the activation energy barrier which allows molecules of relatively low energy to react.

15. Types of enzymes
Pepsin – breaks down protein in the stomach and works well in acidic conditions.

16. Types of enzymes
Pepsin – breaks down protein in the stomach and works well in acidic conditions.
Amylase – saliva enzyme which breaks down starch.

17. Factors affecting enzymes
Heat – ezymes catalyse a reaction faster if the temperature is up to degrees. Above that, the enzyme denatures and can no longer cause a reaction.

18. Factors affecting enzymes
Heat – ezymes catalyse a reaction faster if the temperature is up to degrees. Above that, the enzyme denatures and can no longer cause a reaction.
pH (acidity) – Each enzyme has a range of pH which is it’s optimal pH level = works the fastest.

19. Factors affecting enzymes
Heat – ezymes catalyse a reaction faster if the temperature is up to degrees. Above that, the enzyme denatures and can no longer cause a reaction.
pH (acidity) – Each enzyme has a range of pH which is it’s optimal pH level = works the fastest.
Concentration – enzymes act faster if the substrate or the enzyme is increased.

20. Factors affecting enzymes
Heat – ezymes catalyse a reaction faster if the temperature is up to degrees. Above that, the enzyme denatures and can no longer cause a reaction.
pH (acidity) – Each enzyme has a range of pH which is it’s optimal pH level = works the fastest.
Concentration – enzymes act faster if the substrate or the enzyme is increased.
Chemicals – heavy metal ions such as lead and mercury can slow down or even stop enzyme activity.

21. Factors affecting enzymes
Heat – ezymes catalyse a reaction faster if the temperature is up to degrees. Above that, the enzyme denatures and can no longer cause a reaction.
pH (acidity) – Each enzyme has a range of pH which is it’s optimal pH level = works the fastest.
Concentration – enzymes act faster if the substrate or the enzyme is increased.
Chemicals – heavy metal ions such as lead and mercury can slow down or even stop enzyme activity.

22. Questions
Explain why enzymes are not destroyed by the reactions they catalyse.
The production of C02 by yeast cells during fermentation increases as the temp of the yeast culture is raised from 30 – 40 degrees C. Explain why this increase in production could not continue if the temperature were raised further.
Suggest a reason why life would be impossible without enzymes.
A piece of fish flesh was placed in a sample of liquid in a test tube taken from a cat’s stomach. It was incubated at 37 degrees. What effect would shaking the test tube sample have on the piece of fish flesh?