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Investigating the effect of the substrate concentration on the decomposition of Hydrogen Peroxide by the enzyme catalase.

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Introduction

Investigating the effect of the substrate concentration on the decomposition of Hydrogen Peroxide by the enzyme catalase. Planning Aim In this experiment, I am going to investigate how the concentration of hydrogen peroxide will affect the rate of the reaction. I am going to use different concentrations of hydrogen peroxide as my variable and keep the amount of the liver the same. Background knowledge The formula for catalase breaking down hydrogen peroxide is 2H2O2 ------------> 2H2O + O2 Hydrogen Peroxide is a chemical compound of Hydrogen and Oxygen and the formula for this is H2O2. When hydrogen peroxide is anhydrous it is a colourless liquid which is a strong oxidizing agent which is harmful as it can blister the skin. Catalase is an enzyme (a biological catalyst) for the conversion of hydrogen peroxide into water and Oxygen. Catalase is found in every living cell as it prevents build up of hydrogen peroxide and protects body tissue from damage by H202. Catalase is very important as hydrogen peroxide is consistently being made in metabolic reactions which are chemical reactions taking place inside each cell, catalase is found in large quantities in the liver as a lot of metabolic reactions occur here. ...read more.

Middle

Liver As it contains high amounts of catalase to break down the hydrogen peroxide. Hydrogen Peroxide The substrate in different concentrations as the variable of my experiment. Stop watch To time how long my experiment will go on which will be 60 seconds each time. Diagram Method 1) Set up apparatus( should look similar to above except without liver or hydrogen peroxide yet) 2) Weigh 1g of mashed up liver on a top pan balance and then put the liver into the conical flask. 3) Cautiously measure out 50ml of hydrogen peroxide at 0% concentration in a measuring cylinder. 4) Pour this into the conical flask and securely seal the bung immediately within 2 seconds so that gas cannot escape and start the stop watch straight away. 5) Now gently swirl the conical flask at 60 seconds take the reading of the amount of oxygen that has collected in the gas syringe 6) Clean out the conical flask thoroughly and repeat experiment with 5, 10, 15 and 20% concentrations of Hydrogen peroxide. 7) Repeat each concentration 3 times so that you acquire more accurate results. 8) Calculate the average of each concentration and make graphs. 9) Then from your results work out the rate of each reaction. ...read more.

Conclusion

If the temperature increases too much for example over 50 degrees Celsius the active sites on the enzymes will change and become denatured. This will make the break down of hydrogen peroxide stop and will give me bad results. I also presume that when the concentration gets to high there will be a point where the enzymes will be working as fast as they can all active sites will be occupied at all times and as of this they will not be able to work any faster this means enzymes will reach there Vmax( maximum rate of a enzyme). I think my results should make a sloping graph to a point where it will not rise anymore. This is because of factors like enzymes reaching there Vmax. I predict my results will show a positive correlation as higher the concentration the faster the rate of the reaction as more oxygen will be produced. Results Gas produced after 1 minute (cm�) Concentration (%) Test 1 Test 2 Test 3 0% 0 0 0 5% 4 3 5 10% 21 26 32 15% 68 85 91 20% 71 82 84 Concentration Average Gas produced after 1 minute(cm�) 0% 0.0 5% 4.0 10% 26.3 15% 81.3 20% 79.0 Concentration Average rate of reaction (cm�/s) 0% 0.0 5% 0.06 10% 0.44 15% 1.355 20% 1.316 Rate= Average Volume of Gas Time Taken Biology Coursework Page 1 ...read more.

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