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The aim of the investigation is to find how temperature of affects the rate of reaction in a potato's catalase enzyme with the substrate hydrogen peroxide.

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Coursework Enzymes Introduction: Enzymes are biological catalysts made up from protein. As we know, catalysts are substances that speed up the rate of a reaction without itself being used up. An enzyme has an active site, which has a unique shape into which only a substrate of the exact same unique shape can fit. When this substrate fits into the active site it forms an enzyme-substrate complex: Enzymes can be denatured at certain conditions. These conditions are high temperatures and extreme levels of pH. The bonds that hold enzymes together are quite weak and so are easily broken by the above conditions. When these bonds are broken the enzyme, along with the active site, is deformed, thus deactivating the enzyme. Aim: The aim of the investigation is to find how temperature of affects the rate of reaction in a potato's catalase enzyme with the substrate hydrogen peroxide. Catalase breaks down H2O2 to produce water and oxygen. The oxygen can be collected and used to measure the rate of reaction. Prediction: I predict that the reaction will get quicker as I increase the temperature. But at a certain point it will start to decrease as the enzymes start to denature at high temperatures Preliminary Experiment: Prior to starting the experiment, I first did a preliminary experiment to test the apparatus, and to come to a decision on the quantities of the materials to be used in the experiment. ...read more.


* When bubbles begin to rise in the measuring cylinder, start the stopwatch. When water level has dropped to 2cm3 stop the timer. * Record the results * Repeat experiment using different temperatures each time. I will take 10 results, with the temperature starting at 10�C and increasing at approximately 5�C each time, eventually stopping at 60�C. I will measure how fast the reaction is going by looking at the time it takes to drop 2cm3 of water. The longer it takes the longer it takes to react so the quickest time will be the optimum temperature. Safety: To keep my experiment a safe one I will wear safety goggles at all time and make sure I will try not spilling any Hydrogen Peroxide, but if I do I will wipe it up immediately Research: The enzyme may catalyse a reaction in which the substrate is split into two or more molecules. Alternatively, it may catalyse the joining together of two molecules. When the reaction is complete the product or products leave the active site. The enzyme is unchanged by this process, so now is able to receive another substrate molecule. The rate of reaction can be very quick. For example, the enzyme catalyse can bind with hydrogen peroxide, split them into water and oxygen and release their products at 107 molecules per second. ...read more.


Most human enzymes have an optimum temperature of around body temperature (400C). Results Temperature (0C) Time in minutes Time in Seconds 1/T x 1000 Seconds -1 10 2.30 150 6.7 15 2.12 132 7.6 20 1.25 85 11.8 25 1.20 80 12.5 30 0.51 51 19.6 35 0.58 58 19.6 40 1.00 60s 16.7 45 1.09 69 14.4 50 1.23 203 4.9 55 3.59 239 4.1 60 4.43 283 3.5 I did not repeat my results because it is near impossible to do things identical with enzymes Analysis My results show that the optimum temperature for these enzymes to work is about 30�. This is because heat energy causes more collisions between the particles in the enzyme and particles in the substrate. But at low temperatures the enzymes de-nature changing the shape of the enzymes making it harder for the substrate to fit within the enzyme molecule at very low temperatures the product is rarely completed. Also with out the lack of heat energy it takes a lot longer for the reaction to happen. The same type of thing happens when enzymes are at high temperatures although chemically we are increasing the chances of breakdown, but also increasing the chances of break down of the enzymes. As heat makes the enzymes molecules vibrate this put a strain on the enzymes. Aaron Evans Science Coursework - 1 - ...read more.

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