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What is the effect of pH on the activity of the enzyme catalase?

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Lab Report #2: Enzyme Lab Aim: What is the effect of pH on the activity of the enzyme catalase? Variables: Independent: the different amount of drops of Hydrochloric acid (HCL)/Sodium Hydroxide (NaOH) and the substances which were tested. Dependent: The height to which the bubbles rose in the test tube after the addition of liver (measured in millimetres). Control: Amount of water, (20ml), Hydrogen peroxide (2.5ml) and liver puree (5 drops) in each of the beakers. Background Information: In living organisms, many chemical reactions must take place in order for it to function normally. These chemical reactions involve the breaking and reforming of chemical bonds between substrates of the reaction. However, though many chemical reactions occur spontaneously, processes such as the metabolic pathways, involve multiple chemical reactions which have to occur in a specific order. This is where a biological catalysts, known as the enzyme, plays a very important role. You see, enzymes have the task of catalyzing, (or speeding up), chemical reactions in a cell, all so that they can occur in a timely and sequential manner. The enzyme catalase, for instance, has the role of breaking down the toxic Hydrogen peroxide in animal and plant cells. Hydrogen peroxide is the byproduct of metabolism that has the ability to destroy cells if not removed. ...read more.


Add 2.5 ml of Hydrogen peroxide (H202) to the beakers. Measure the volume, (in millilitres), of the bubbles produced in each of the beakers. Record the results in a table. Data: Beakers Contents pH of substance Added contents Volume of bubbles (ml) 1 10 drops of HCl and 20ml of water 2 5 drops of liver puree & 2.5 ml of Hydrogen peroxide (H202) 12 2 20ml of water and 5 drops of HCL 4 5 drops of liver puree & 2.5 ml of Hydrogen peroxide (H202) 10 3 20ml of water 7 5 drops of liver puree & 2.5 ml of Hydrogen peroxide (H202) 0.8 4 20ml of water and 5 drops of NaOH 9 5 drops of liver puree & 2.5 ml of Hydrogen peroxide (H202) 2 5 10 drops of NaOH and 20ml of water 11 5 drops of liver puree & 2.5 ml of Hydrogen peroxide (H202) 1.9 Conclusion: Enzymes work within certain limits. One of these limits is pH, (otherwise known as the acidity level), at which an enzyme has an 'optimum' pH, which is basically the pH at which the enzyme works best. The further away an enzyme is from it's optimum pH, the less efficiently it begins to work, eventually becoming denatured. ...read more.


By mistake, some beakers were placed in the wrong order, and we were unsure as to whom they belonged to. We guesstimated the number of each of the beakers, and continued to work. In order to resolve this issue, though it would have consumed more time, we should have worked as a group, and dealt with one beaker at a time. This would have made the experiment far easier, and we would have definitely obtained better results. Another human error was the amount of Hydrochloric acid and Sodium Hydroxide added to the beakers. For beaker number 2, we were supposed to add 5 drops of HCl. However, after adding a few drops, we had lost count, as so we practically guessed the remaining drops which we would have to add. Though this probably wouldn't have made such a large difference in terms of the entire experiment, it could have still affected our results. To improve this error, we should have been more careful in measuring and adding the drops of HCl. Finally, we didn't measure the volume of the bubbles incredibly accurately. In beaker number 2, there was a disagreement between members in our group whether the bubbles rose 9ml or 11ml. Without properly measuring the volume, we simply assumed, by taking the average, that the bubbles were 10ml in height. To improve this, we should have accurately measured the volume of the bubbles in the cylinder. ...read more.

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