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How does a change in temperature effect the activity of the catalase enzyme on a piece of liver?

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BIOLOGY COURSEWORK INVESTIGATION How does a change in temperature effect the activity of the catalase enzyme on a piece of liver? PLANNING Background knowledge An enzyme is a biological catalyst; it alters the rate of reaction without being changed itself. Enzymes are proteins; they have a very precise three- dimensional shape, which forms a one specific active site on the enzyme. Each enzyme can only convert one kind of substrate molecule into one kind of product molecule. What affects Enzymes? - Temperature - Enzymes start to denature if the temperature rises above 37.5 C Increasing the temperature alters the three - dimensional shape of the enzyme therefore the enzyme can no longer fit the substrate - pH - Enzymes work best in neutral conditions neither acidic or alkaline. What effect does catalase have? Catalase is a very fast reacting enzyme, it is found in many living cells, it breaks down hydrogen peroxide to water and produces oxygen. In fact one molecule of it can deal with six million molecules of hydrogen peroxide in 1 minute. Hydrogen peroxide is toxic so it needs to be changed into harmless substances. The equation for the reation: 2H202 Catalase 2H20 + 02 Reference to praticals referring to enzymes - Biology for You Pg. 30 - Experiment 3.1 From looking at this I found that the catalase reacts with the hydrogen peroxide to give out water and oxygen. ...read more.


- Take the measurements of hydrogen peroxide and water at eye level and on an even surface and with a 90-degree angle to the lab bench from the measuring cylinder. - Take each reading three times to ensure that there isn't and anomalous result. Three is a good number to use as you can see the if there is an anomaly whereas if I was to take each reading twice I wouldn't be able to distinguish the anomaly. Also I am able to obtain an average. To make sure I am carrying out a safe experiment I will make sure that I am wearing safety glasses, as the hydrogen peroxide is corrosive and an irritant. I will also carry out any other safety precautions e.g. hold hot beaker with tongs. Prediction Taking into account my research I believe that the amount of gas given off by the reaction will increase as I increase the temperature that the reaction takes place in. The amount of gas given off will start to decrease after 37.5C and any other temperature above that. This is because the enzyme is denaturing. Reason being that enzymes are proteins and their structure is three dimensionally. Increasing the temperature disturbs the intra - molecular bonds that hold the 3D shape. As a result of this the shape has been altered. Enzymes have an active site. This fits into the substrate molecular. If the active site is altered the substrate will no longer fit in and so the enzyme doesn't work properly. ...read more.


- I would take longer to carry out the experiment and achieve more results, therefore improving the accuracy of my results. - As well as changing the temperature at which the enzyme works I would also change the weight of the liver piece. I would investigate if the change in temperature has more of an effect than the amount of enzyme present. - I would maybe take more results (5 tests) to give me even more reliable evidence and a more accurate average. - I would see how temperature effects other enzymes such as pepsin or trypsin, which bring about the digestion of meat - I would investigate the effect of enzymes in different conditions (changing pH levels). There isn't really another way of carrying out this experiment, except for using the suggestions and improvements that are above. What would be the most interesting extension to this work is to see what pH conditions the liver enzyme works best in. Diagram I would use different pH levels and measure have much oxygen gas is given off. I would use the same procedure for the method above, but I would use different pH levels instead of the hydrogen peroxide. I wouldn't apply heat at first I would just see which pH level the liver enzyme works best in and maybe apply heat to that. I wonder if I would see the same effect? ...read more.

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