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Enzymes & Temperature: Extended (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))
Revision Note
Enzymes & Temperature: Extended
Extended Tier Only
- Enzymes are proteins and have a specific shape, held in place by bonds
- This is extremely important around the active site area as the specific shape is what ensures the substrate will fit into the active site and enable the reaction to proceed
- Enzymes work fastest at their ‘optimum temperature’ – in the human body, the optimum temperature is 37⁰C
- Heating to high temperatures (beyond the optimum) will break the bonds that hold the enzyme together and it will lose its shape -this is known as denaturation
- Substrates cannot fit into denatured enzymes as the shape of their active site has been lost
- Denaturation is irreversible - once enzymes are denatured they cannot regain their proper shape and activity will stop
Effect of temperature on enzyme activity
- Increasing the temperature from 0⁰C to the optimum increases the activity of enzymes as the more energy the molecules have the faster they move and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction
- This means that low temperatures do not denature enzymes, they just make them work more slowly
Graph showing the effect of temperature on the rate of enzyme activity
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