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The effect of substrate concentration on the rate of decomposition of Hydrogen Peroxide when catalysed by the enzyme Catalase.

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Introduction

Chemistry Coursework The effect of substrate concentration on the rate of decomposition of Hydrogen Peroxide when catalysed by the enzyme Catalase. Plan In this experiment I have to investigate experimentally, the effect that substrate concentration has on the overall rate of decomposition of hydrogen peroxide when catalysed by the enzyme Catalase. First I need to understand the hypothesis before starting the experiment. We have looked at the function of enzymes, the way they carry out reactions and also the effects of conditions on their reactions. Also the lock and key hypothesis, and the more recent induced fit model, enzyme- substrate complexes, and activation energies with and without enzymes, specificity and also the cause of denaturation of the enzyme. In organisms, such as ourselves, Hydrogen Peroxide is a by product of our metabolism. The oxidations of certain cells in our body produce this toxic chemical. The chemical itself is pretty stable, and can last for prolonged periods of time in our body, and because of it's toxicity, it must therefore be removed quickly. Catalase is the enzyme that will reduce the activation energy (energy needed to start a reaction), and increase the rate of the decomposition of Hydrogen Peroxide, so there is less chance of it intoxicating our cells. In this experiment, the source of our Catalase enzyme will be potatoes. It works very quickly to reduce levels of Hydrogen Peroxide when present. ...read more.

Middle

But adding too much substrate doesn't mean that the rate of reaction will continue to increase, this is because the enzymes will only have a limited amount of active sites, so when the maximum amount of reactions are taking place, the enzymes are said to be saturated as no further active sites are available until some of the reactions have taken place. Therefore the graph for this experiment should show gradual increase in rate as the substrate increases, but reach a maximum point and level out, when all the enzymes active sites are in use, as the graph shows below. From this information I know that my graph should definitely show an increase in rate of reaction as I increase the substrate concentration. I know that if I increase the substrate concentration by double, the rate of reaction will increase by double, so the rate is proportional to the substrate concentration, until the saturation point. 3) Enzyme Concentration The enzyme concentration is obviously as vital as the substrate concentration. This is because the enzyme provides the active site to which the substrate joins to form an enzyme-substrate complex. The enzyme most importantly catalyses a reaction, meaning it reduces the energy required to start a reaction, the first graph below shows this reduction of activation energy. So therefore increasing the enzyme concentration will provide more active sites for the substrate, Hydrogen Peroxide to form a complex with, allowing more products to be formed. ...read more.

Conclusion

Therefore if there are double the amount of substrate/enzyme molecules in a solution, double the amount of reactions will take place at once and the rate will therefore double as well. Safety Risk Assessment: Apparatus * Potatoes (Are the source of the enzyme Catalase) * Cork Borer ( To cut same sized potato rings) * Hydrogen Peroxide (Substrate forms enzyme-substrate complex with Catalase) * Ruler (To measure out equal sized potato pieces) * Scalpel (To cut the measured sized potato pieces) * Stopwatch (To measure the rate of reaction in each experiment) * Test Tubes and Rack (To hold the enzyme-substrate solutions) * Delivery Tube with Bung (To let Oxygen to pass through test tube into burette) * 50 cm3 Burette (To measure amount of Oxygen released at regular time intervals) * Water Bath (To use at different temperatures with enzyme-substrate solution) * pH Levels 2 to 7 (To use with enzyme-substrate solution under various pH's) * Thermometer 50�C (To measure room temperature and solution temperature) * Pipette Filler 10cm3 (To measure amount of Hydrogen Peroxide used) * Retort stand, Boss and Clamp (To support and hold the burette and test tube) APPARATUS USED ACCURACY Burette (50cm3 ) 0.05cm3 Thermometer 50�C 0.1�C Pipette Filler (10cm3) 0.06cm3 Stopwatch 0.5 seconds Methods: Temperature * Substrate Concentration * ?? ?? ?? ?? Khuram Pervez Page 1 of 10 ...read more.

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