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Investigating an enzyme-catalyzed reaction

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Investigating an enzyme-catalysed reaction Introduction Our experiment involves us testing the rate of reaction by using hydrogen peroxide and the enzyme called catalase. The catalase in this experiment is an enzyme with an active site (place where substrate fits) which fits hydrogen peroxide (a poison produced by all cells). This is an example of a lock and key model where the substrate molecule fits in to the enzyme. Enzymes are used to speed up chemical reactions in the body. Catalase is found in all living cells and is specific for the breakdown of hydrogen peroxide. The catalase can become denatured through heat and pH. The catalase will be used to break down the hydrogen peroxide into water and oxygen. The equation for this equals: Catalase 2H2O2 2H2O+O2 This is another diagram to show how an enzyme (invertase) can break down sucrose into to smaller sugars- glucose and fructose. At the end of the reaction, the enzyme is unchanged and can catalyse the breakdown of another molecule of sucrose: After looking at the scientific understanding of what is required I have thought about what sort of method I would use to get a good set of results. I have also reviewed what I will need to check during my preliminary investigations to make sure that I get the most reliable set of results I can. I have also thought about what change in variable I will make that will be easiest to achieve and to get the best set of results. Hydrogen Peroxide Hydrogen peroxide (H2O2) is a very pale blue liquid, slightly more viscous than water that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. Nearly all living things possess enzymes known as peroxides, which harmlessly and catalytically decompose low concentrations of hydrogen peroxide to water and oxygen. Variables There are lots of different factors that can affect the rate of the enzyme reaction. ...read more.


We will use the jars to hold the reactants in before we pour them into the boiling tube. The holding wrack is important to hold the measuring cylinders upright. 5) Then you will need to get the boiling tube which has to be attached to a delivery tube- It needs to be attached to the delivery tube as that is where the displaced water will go through and then up the burette. The jar should be a smallish size as we are measuring air leaving the reaction tube from the reaction. 6) After you must attach the delivery tube to the boiling tube and then carefully lift the burette up and stick the other end of the delivery tube up the burette- The delivery tube is one of the most important things in this chemical reaction. We use the delivery tube to transfer air lost by the reactants through the delivery tube and up the burette which is filled with water. This is how the water is displaced. 7) Then you will need to collect a stopwatch- The stopwatch is used to measure how much water is displaced in 20 seconds, it is a much more reliable way than just counting 20 seconds. 8) Then you will need to collect the reactants which are: a jar full of hydrogen peroxide, yeast solution and distilled water- These are the reactants that we have choose to do to investigate. The hydrogen peroxide will act as the catalyse. Before I use my reactants I must test the temperature of them to make sure that it is a fair test and that I control the variable temperature. When I do this I am making sure that I am keeping a fair test because I am controlling the variable. 9) Now firstly you must label all the three jars and the three cylinders with what reactant the will have in them. ...read more.


Especially as our experiment ran other a few days the pH may have been different meaning that there might have been a slight change in the temperature of the solution. Our method did work well though because we made sure that we collected all the equipment at the beginning it meant that we could work through it quickly especially when it was performed with a partner. If you look through my data you cannot defiantly say that these results are 100% reliable. I say this because we have a large variety of results. In all different amounts of concentration I have found at least 1 outlier in all three tests. In the 3ml yeast concentration the results were so spread out that it was hard to see which one was around about the correct result. Another minor problem with the data is the fact that I only have 5 different concentrations, if I was to get a stronger and more reliable set of results I would have had to of tested more concentrations to see if the line on the graph went in the same direction. Another thing that could have made my data more reliable if I would have further tested each concentration 5 or 7 times each then you could really get a nice set of results that should start to show real evidence that backs up the scientific understanding. I would have performed these steps initially but it would have taken up more time. Time is a problem for all scientists as they are usually pushed to get the best result as quick as possible and it is also financially better to get your evidence out there before anyone else can. Conclusion After looking at my data I would say that there is a strong correlation between increase in yeast concentration and faster rate of reaction however for this to be positive I would need to collect more results with the improvements I decided to make for my method. ?? ?? ?? ?? ...read more.

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