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Inhibition of the decomposition of hydrogen peroxide by the catalase enzyme using copper sulphate.

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Inhibition of the decomposition of hydrogen peroxide by the catalase enzyme using copper sulphate. Hydrogen peroxide is broken down by the enzyme catalase into water and oxygen. Enzymes are catalysts that speed up the rate of metabolic reactions. These reactions can take place without the catalyst but take a considerably longer amount of time. Enzymes can either break down larger molecules into smaller molecules or build smaller molecules into larger ones. In the case of hydrogen peroxide, larger molecules are broken down. All enzymes are globular proteins held together hydrogen bonds, ionic bonds and disulphide bridges in a distinct three-dimensional shape and its shape is specific to each enzyme, as one substrate will fit only one active site. This is illustrated in the 'Lock and Key Hypothesis.' The lock and key hypothesis was to explain why enzymes are specific and will only work on particular substrates. The hypothesis tells us that the substrate fits the active site exactly and because every substrate is different each enzyme has an active site the correct shape for only one substrate and they have to fit each other exactly. ...read more.


High pH has a similar effect, but has an increase in Hydroxyl ions and this means both become negatively charged at repel each other. Some enzymes require cofactors before they can catalyse the reaction. Cofactors are non-protein molecules, which modify the chemical structure of the enzyme so it can function more effectively. Inhibitors: Inhibitors are substances that decrease the rate of reaction. This is achieved by the inhibitor binding with the enzyme and preventing it from forming and enzyme-substrate complex. Inhibitors can either be reversible or non-reversible. If an inhibitor is reversible the effect is only temporary and can be reversed when the inhibitor is removed. There are two types of reversible inhibitor; the competitive inhibitor and the non-competitive inhibitor. The competitive inhibitor has a similar structure to the substrate and is therefore able to bind with the active site. This decreases the number of active sites available to bind with the substrate, there fore decreasing the rate of reaction. Increasing the substrate concentration can decrease the effect of the inhibitor, as there is more substrate to compete for the active sites. The non-competitive inhibitor attaches to another part of the enzyme and its presence alters the overall structure of the enzyme, including the active site, therefore preventing the enzyme-substrate complex being formed. ...read more.


5. Repeat with other 5 samples. Results: Vegetable Volume of Hydrogen gas given off. (Cm3) Potato 8 8.5 Carrot 7 6 Swede 4 5 Parsnip 5 7.5 Errors: * The pipettes used to measure the volume of Hydrogen peroxide has an error of 0.05ml * The ruler used to measure the length of the potato has an error of 0.5mm. This is 0.5mm3 as the potato is a cylinder. * The gas syringe has an error of 5cm3 * The thermometer has an error of 0.05�c. When these errors are taken into consideration, the overall error is 5.1cm3. Vegetable Vol. of hydrogen gas (Cm3) Vol. Of Hydrogen gas (Cm3) Potato 8 - 13.1 8.5 - 13.6 Carrot 7 - 12.1 6 - 11.1 Swede 4 - 9.1 5 - 10.1 Parsnip 5 - 10.1 7.5 - 12.6 These results show that potato contains the highest level of the enzyme Catalase as potato gave off the highest volume of gas in a fixed amount of time, which tells me the rate of reaction is highest with potato as the catalyst. The potato is a catalyst because it naturally contains the enzyme Catalase. Therefore in my investigation to find the effects of different concen trations of the inhibitor copper sulphate I will use potato as the catalyst. ...read more.

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