Effect Of PH On Enzymes- Experiment Flashcards
What does the experiment investigate?
It investigates how the PH affects the time taken for the enzyme amylase to digest (breakdown starch)
The pH of the reaction mixture is varied by adding a buffer solution. This is a solution that has a constant know pH value.
The reaction is followed by testing with iodine solution. If there is any unreacted starch present, it will react with iodine to give a blue-black colour. When the reaction is complete there won’t be colour change
Explain the method
1) put a drop of iodine solution into every well of a spotting tile
2) Place a bunsen burner on a heat proof mat, and a tripod and gauze over the bunsen burner. Put a beaker of water on top of the tripod and heat the water until it is 35 degrees, using a thermometer to measure the temperature. The temperature of the water should be remained constant
3) Using a syringe to add 1cm3 of amylase solution and 1cm3 of a buffer solution with a pH of 5 to a boiling tube. Using test tube holders put the tube into the beaker of water and wait for five minutes
4) Next use a different syringe to add 5cm3 of a starch solution to the boiling tube. Immediately mix the contents of the boiling tube
5) Use continuous sampling to record how long it takes for the amylase to break down all of the starch. When the iodine solution remains browny-orange starch is no longer present
6) Repeat the whole experiment with buffer solutions at different pH values to see how pH affects the time taken for starch to be broken down
What are the control variables?
Concentration and volume of the amylase solution to make it a fair test
How do you calculate the rate of a reaction?
Rate = 1000/ time
