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Investigate the factors affecting the activity of the enzyme catalase

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Aim The aim of this experiment was to investigate the factors affecting the activity of the enzyme catalase. Also, to do the experiment safely and fairly so that the results obtained are reliable enough to support my conclusion. Factors There are many factors that will affect the acidity of the enzyme catalase. Below are the factors and a description of how they will affect the equipment. Temperature If the temperature increases, the reaction between the enzyme and the substrate will occur quicker. This is because; as you increase the temperature the particles get more energy so they bump into the other particles breaking down quicker. This occurs, as there is more contact between the active site and the substrate. It the temperature becomes to high the enzyme will break down and become denatured. Temperature The graph above shows how the increase in temperature affects the enzyme. Then when the optimum temperature is reached the enzyme becomes denatured causing the reactions to slow down until it completely stops. This is shown by the curve on the graph. PH An enzyme is affected by the pH. Some enzymes work best at neutral others work best in acidic or alkali conditions. All enzymes have an optimum pH that they work best at. The optimum pH can be affected by its position in the body. For Example: - Mouth enzymes optimum pH is slightly alkali to neutralise the food. Stomachs enzymes optimum pH is slightly acidic to break down the food. Acidic present means lots of concentration of hydrogen ions H Alkali present means lots of concentration of OH ions. Depending on the acid or alkali present can change the shape of an enzyme. ...read more.


Equipment The equipment you need for this experiment is: 1 ice cream tub 2 measuring cylinders Boiling tube rack Boiling tube Bung Tube Stop clock Pipette Tile Potato Potato cutter Knife Ruler Goggles Method First, the equipment needs to be gathered and set up as shown below. Put on goggles before handling any of the chemicals. You need to fill the ice cream tub up with water and fill the measuring cylinder up with water making sure that there is no air in the cylinder. The measuring cylinder must then remain in the water with the tube in the end. During the experiment you must check that the tube does not come out from the cylinder, as the oxygen would escape. Then 30cm of Hydrogen peroxide must be measured out and then added to the boiling tube. The potato needs to be pushed through the cutter so that all the chips are the same depth and width. They must then be cut to the correct length. Starting with 0.5 cm and going to 3cm. This must be done on a tile. The chip then needs to be added and the stop clock needs to start strait away. The bung must be pushed into the boiling tube with the tube in the top of the bung. Every 30 seconds read off the measuring cylinder how much oxygen is in it. Keep taking the readings every 30 seconds for 5 minutes. It must always be carried out in a neutral pH and it must be done at room temperature. This method needs to be repeated for all the size chips ranging from 0.5cm up to 3 cm increasing 0.5cm every time. ...read more.


I believr that the reason why my results were not directly proportional is that I had to use a different potato half way through the test. This means that the amount of enzymes it contained could have been slightly different. The anamonous results where my 3cm of potato ones. I believe that this again could be down to the change in potato or the bung may not have been in fully so some of the oxygen may have escaped and not have been measured. The tube may also have been blocked so the oxygen may never got through to be measured. I feel the way I measured the height of the froth was very accurate. After trying in my peliminary test by measuring it with a ruler I feel the method I used gave much more precise readings. If im was to re do this experiment I would make sure that I used the same potato and the same enzyme solution every time as this may have lead to the anomolus results. If I want to do futher work I could try measuring the gas given off by using a gas suringe. This would work by having the test tube set up the same as befor but this time having the tube leading into a suringe so as the oxygen is forced out is pushes the suringe so that the reading can be taken. This method would be a lot quicker and you don't have to worry about the tube coming out from the bottom of the test tube. However the suringe would need to be very big on some of the larger pieces of potato. The same experiment could be done using exactly the same method as I stated but by using different substances that catalase is present in. ...read more.

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