An experiment to see the effect of pH on the activity of Catalase

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Investigation on the effect of the pH on the activity of Catalase

An experiment to see the effect of pH on the activity of Catalase

Secondary resources: from my research I carried out, I have learnt that:

Catalyse is an enzyme that is found in foods such as potato and liver. Catalyse speeds up the decomposition of hydrogen peroxide into water because the shape of the hydrogen peroxide molecule. This type of where a molecule is broken down into smaller pieces is called an anabolic reaction. This enzyme catalysis is the breakdown of hydrogen peroxide and it forms oxygen gas and water.

Enzymes are very large and complex organic molecules that are synthesized by the cell to perform very specific functions. These biological catalysts are important because they speed up the rate of the reaction they catalyze that would otherwise be too slow to support life. Catalyse is an enzyme present in the cells of plants, animals and aerobic bacteria. It promotes the conversion of hydrogen peroxide, a powerful and potentially harmful oxidizing agent, to water and molecular oxygen.

Catalase is located in a cell organelle called the peroxisome. Peroxisomes in animal cells are involved in the oxidation of fatty acids, and the synthesis of cholesterol and bile acids. Hydrogen peroxide is a by-product of fatty acid oxidation. White blood cells produce hydrogen peroxide to kill bacteria. In both cases catalase prevents the hydrogen peroxide from harming the cell itself. Peroxisomes in plant cells are involved in photorespiration and symbiotic nitrogen fixation (the breaking apart of the nitrogen molecule N2 to reactive nitrogen atoms). Hydrogen peroxide is produced as an intermediate during these chemical processes and must be removed to prevent damage to cellular machinery. Aerobic (oxygen requiring) bacteria produce hydrogen peroxide as a by-product of metabolism. This fact is used when identifying bacteria. If hydrogen peroxide is added to a bacterial colony and bubbles are produced, this is evidence of oxygen production and confirms that the colony is aerobic.

The activity of catalase can be measured by finding the rate at which the oxygen gas is released from the decomposition of hydrogen peroxide.

The buffer solutions that I am using are pH – 4.4, 5.2, 6.5, 7.5 and 8.4.  

Hydrogen peroxide = 2H2O2

Hydrogen peroxide + catalase -> oxygen + water

The books and resources I used were:

Energy and chemistry – p229

Gareth Williams, biology for you pages 29-31

 – enzymes, catalase, hydrogen peroxide

OCR staged assessment phase 1 module by Mary Jones

Pre-test:

  • In the pre-test I done it by putting my pH and hydrogen peroxide mixed solution in the syringe
  • Then put the potato in the conical flask
  • Put the bung on
  • Put water in the measuring cylinder and put it upside down without the water coming out
  • I then put the delivery tube in the measuring cylinder
  • I got the stop watch
  • Started the time when I pushed the mixed solution in the conical flask with the potato
  • Stopped the time when the gas was collected 10cm3
  • Recorded my result in a table
  • Repeat that experiment another 2 more time
  • Do the other pH solutions
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The second row in my table has got the anomalous result. It can’t have been 90.1 because that is too much to be the average set of results. This happened because I let some gas out as I was holding the cylinder, I didn’t realise the tube came out and then I thought why is it taking so long. In my pre-test I had some mistakes, they were firstly I didn’t use hydrogen peroxide with my pH, so I had to do the whole experiment again. The second mistake was, the gas I was measuring I wasn’t too ...

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