An Investigationinto the Effect of Ph on the Activity of Potato Tissue Catalase

1537 Words May 3rd, 2008 7 Pages
An Investigation Into The Effect Of PH On The Activity Of Potato Tissue Catalase
Aim
The aim of my investigation is to see how pH affects the activity of potato tissue catalase, during the decomposition of hydrogen peroxide to produce water and oxygen. Catalase + 2H2O2 Catalase + 2H2O +O2
Catalase + Hydrogen Peroxide Catalase + Water + Oxygen
Independent Variable
The independent variable in this investigation is pH. Each individual enzyme has it’s own pH characteristic. This is because the hydrogen and ionic bonds between –NH2 and –COOH groups of the polypeptides that make up the enzyme, fix the exact arrangement of the active site of an enzyme. It is crucial to be aware of how even small changes in the
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Buffer Solutions
To prevent fluctuation in the pH, a solution known as a “buffer solution” was used in the experiment. Buffer solutions are mixtures of at least two chemicals which counteract the effect of acids and alkalis. Therefore, when a small quantity of alkali or acid solution is added the pH of the enzyme doesn’t change.
To make the buffer solution you need 0.2 mol dm-3 of Na2HPO4 and 0.1mol dm-3 of citric acid this will give 100cm3 of buffer. Here is how to get the different pH in the buffer solutions:

pH Na2HPO4 cm3 citric acid cm3
3 20.55 79.45
5 51.50 48.50
6 63.15 36.85
7 82.35 17.65
8 97.25 2.75
9
Apparatus
• Spotting tiles
• Stopwatch
• Three potatoes
• Cork borer
• Distilled water
• Beakers
• Buffer solution (5cm3)
• Hydrogen Peroxide (5cm3)
• Pipette
• Six boiling test tubes with rubber bungs
• Measuring Cylinder
• Manometer
• Stand, bosses and clamps
• Ruler
• Scalpel or razor blade
• Paper towel
• Rage of base (0.1M, 0.2M, 0.4M, 0.6M, 0.8M 1.0M)
Method
1. Label al the beakers all the beakers and test tubes with the appropriate pH.
2. Cut the potatoes using a cork borer approximately 5cm in length and 1cm in diameter. Using the appropriate tool cut the potatoes into cylinder form measuring the cylinders with a ruler.
3. Measure and add 5cm3 of buffer solution using a measuring cylinder with the pH 3 into a test tube using a pipette and place the potato cylinders into the test tube.
4. Place the apparatus as shown in…