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Aim: Determine the optimum temp or PH of an enzyme

IV ~ Temperature or PH DV ~ Time for substrate to be broken down

Amylase breaks starch down into maltose

1. Put a drop of iodine solution into each well of a spotting tile
2. Measure out 1cm3 of amylase and 5cm3 of starch solution and place separately to heat using a bunsen burner or a water bath
3. If changing the PH, heat 1cm3 of buffer solution along with the other solutions
4. Mix the reactants together and start a stopwatch
5. Use continuous sampling by adding a sample of the mixture to wells in the spotting tile every 30 seconds until the colour NO LONGER changes from orange to blue-black (starch is broken down)
6. Use a range of buffer solutions with at least 3 pH values or use a range of temperatures
7. Repeat 3 times for each PH/temp and calculate a mean time to plot on a graph against PH/temp

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Control variables

• keep volume of amylase the same
• keep concentration of amylase the same </aside>

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RISKS

• Bunsen burner ~ use a heatproof mat, close the hole when its not in use so that the flame is visible </aside>

The optimal PH or temperature is between the 2 lowest points on the graph because that’s when it took the least amount of time for the starch to be broken down.

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