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In this investigation we are going to investigate how temperature affects the activity of the enzyme catalase.

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How Temp Affects Catalase Planning In this investigation we are going to investigate how temperature affects the activity of the enzyme catalase. We will do this by measuring hoe much of the gas oxygen is produced within a set time of five minutes. Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide to oxygen and water; Diagram Delivery Tube Boiling Tube Thermometer Measuring Cylinder filled with water being displaced by oxygen bubbles Water Bath Bowl Water Potato Hydrogen Peroxide Stopwatch Apparatus * Potato * Craft Knife * Tile * Cork Borer * 5x Water Baths * 5x Thermometers * 3x Boiling Tubes * 3x Delivery Tubes * 3x Small Measuring Cylinders * Bowl filled with water * Stopwatch Catalase is present in potato tissue. Pieces of potato will be put into some hydrogen peroxide. The catalase in the potato will catalyse the breakdown of the hydrogen peroxide into water and oxygen, and the oxygen will pass through the delivery tube and displace the water in the measuring cylinder. The level at which the water begins will show us the volume of oxygen produced, giving us a measure of the activity of the enzyme. The rate of oxygen production will be measured at different temperatures. The rate of an enzyme-controlled reaction can be affected in several different ways. Temperature affects the activity of enzymes. A higher temperature would give the substrate molecules more kinetic energy because the heating of molecules causes the atoms to vibrate more giving the molecule more energy for movement, so that when they collide with the enzyme they will have more energy and are more likely to bind with the active site because they will be moving around quicker and covering a larger area quicker. An increase in temperature also causes enzyme molecules to gain in energy as they to will begin to vibrate more with the temperature increase. ...read more.


Bonds breaking Ammonia Water Rate Heating up Heating up Heat This graph shows how the heat capacity of water is much more than of ammonia because the ammonia has a steeper gradient than the water. This means that ammonia will heat up much more easily than water. We will deliberately not vary the pH, surface area of potato, concentration of potato, enzyme and hydrogen peroxide throughout the investigation to make sure that it is a fait test and because no potato is the same because of their age, type or crop, we will use the same source of enzyme, the same potato, to make the investigation a fair test. Prediction In this investigation, I predict that, as the temperature rises, the rate of enzyme activity will increase until the high temperatures denature the enzyme and the rate of enzyme activity will decrease. The enzyme will denature because when the temperature increases the atoms within the enzyme molecule will begin to vibrate, at first the rate will be low because the enzyme will not be vibrating much so it will not have much energy for catalysing the reaction. The more the temperature increases the more the atoms will vibrate which will begin to knock the enzyme out of shape and denature it until the active site of the enzyme will no longer match up with its specific substrate molecule. The collision theory also states that as the temperature increases, the rate of reaction increases because the particles move about faster. The collision theory states that the rate of reaction depends on how often and how hard the reacting particles collide with each other. That the particles have to collide with each other to react, and they have to collide hard enough. So more collisions increases the rate of reaction When the temperature is increased the particles all move quicker. If they're moving quicker, they're going to have more collisions. ...read more.


* Use a thinner measuring cylinder to collect oxygen because it would be more accurate. * Use a more precise, digital thermometer because it would give us more accurate temperatures to more decimal places. * Take more results around where the optimum is to have more confidence about the results. The method, which I used, is reliable and can be counted on to give accurate results. The use of a sketch graph during the experiments helped me with this because it allowed me to identify if a large amount of anomalous results appeared and then they could be repeated. Also, there are no evident random errors, errors that have aroused by fault of myself or any systematic errors, an error that has aroused because of fault with the apparatus. I think I have enough evidence to draw a conclusion, as most of my results are close to the line of best fit, which gives me, confidence that my results are correct. Also, all the data agrees with the hypotheses, theories and predictions making it seem accurate, correct and reliable. To obtain more evidence to support my conclusion I could compare my results with others to identify any systematic errors and if the results were the same it would give me even more confidence in them. You could use other methods of measuring enzyme activity; use a different source of catalase, such as liver. Or use just catalase, extracted from the source and if the same results were always produced then that would support my conclusion solidly. CONCLUSION The optimum temperature at which catalase catalyses a reaction at the quickest rate is 30?C. As temperature increases during an enzyme catalysed reaction, the enzyme activity rate increases as well until the enzyme reaches its optimum and is denatured by the vibrations of its atoms becoming too vigorous and knocking it out of shape because the temperature rise has caused them to gain more energy. Then, as the temperature rises, the enzyme activity rate drops because the enzyme is no longer the right shape to catalyse the reaction. ...read more.

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