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Enzyme Investigation

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Enzyme Investigation Preliminary Work I chose to use the different apparatus in my experiment from preliminary work I have done. I could have used liver instead of potato but liver reacts too much with the hydrogen peroxide and too quickly to be able to record the results with any accuracy. This is because it has too many catalaes enzymes, so the reactions take place a lot quicker. There was a choice between counting the number of bubbles released and the volume of oxygen released. I chose volume because it is more accurate as bubbles can easily vary in size and it is easier to record the volume than counting bubbles. 5g of the potato and 20cm3 of the Hydrogen Peroxide should be enough for this experiment to produce easily read results, which will also be accurate enough for me to see clearly which is best for reactions. Hypothesis I am trying to find out if Hydrogen peroxide will breakdown to oxygen and water in the presence of Catalase. The reaction will increase with increasing substrate concentration. Structure and Function of an Enzyme Enzymes are large proteins that speed up chemical reactions. In their globular structure, one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, or the location on the enzyme where the substrate binds and the reaction takes place. ...read more.


All measurements of potato will be made to 2d.p. This will increase accuracy. Method I will then get the equipment I need for the experiment. I will then get 5g of potato will be measured out on the electric scales, this will be measured to 2 decimal places. This is accurate enough for the experiment I will do. I will fill the basin with water next and then fill the measuring cylinder as well. The measuring cylinder will be placed upside down in the basin still full of water, making sure that no water is escapes so that the experiment is fair. I will then put the potato pieces in the boiling tube. The next thing that must be done is to put the delivery tube and bee hive shelf together and place the delivery tube under the measuring cylinder so that any gas pushed through will go into the measuring tube. I will then make up different strengths of Hydrogen Peroxide solutions, which will be measured out using a small measuring cylinder; these concentrations are shown in the table below; Concentration volume of stock volume of de- Of H2O2 H2O2/CM3 ionised water cm3 10% 2 18 20% 4 16 30% 6 14 40% 8 12 50% 10 10 I will then add these concentrations in with the potato and the stopwatch will be started. ...read more.


I have succeeded in what I planned to do, which was to find out how the concentration of H2O affects the amount of oxygen produced in an enzyme catalysed reaction. The results I wrote down were what I had expected and predicted. An inaccuracy is when the experiment was started; the measuring cylinder may have still had some air bubbles inside it. This makes the results slightly less accurate. Another thing is that when the potato and the Hydrogen Peroxide were put into the boiling tube, they may have mixed slightly causing some oxygen to be lost. I feel my experiment was a good procedure to use because it gave good results that were similar to what I had expected. The temperature was not the same on both days so this may have changed the results slightly. The enzymes may have denatured in some experiments because of the potato being exposed to the air, some people may not have sealed the boiling tube properly. Also more substrate concentrations could have been used to prove the whole experiment was correct. Another thing to be done would be to do more repeats for each concentration; this would make results more accurate when finding averages. This experiment could also be done the same except changing something else each time, like the amount of potato, keeping the same concentration of the substrate. ...read more.

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