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The aim of this experiment is to determine the effects of varying temperatures on the enzyme Catalase. I will find out if and how temperature affects an enzyme's rate of reaction.

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Biology Coursework: INVESTIGATING THE FACTORS THAT AFFECT ENZYME CONTROLLED REACTIONS Planning: The aim of this experiment is to determine the effects of varying temperatures on the enzyme Catalase. I will find out if and how temperature affects an enzyme's rate of reaction. The enzyme catalase will be from a potato. Catalase is present in all organisms and its job is to break down Hydrogen Peroxide. Hydrogen Peroxide is a form of bleach; we use it on our hair. This is a harmful product of metabolism. I will get this sample by boring a hole through a potato; I will have to make sure that each potato sample is the same mass or length. Hydrogen Peroxide + Catalase ------> Water + Oxygen There are many factors, which could affect the rate of an enzyme-controlled reaction. These include: Temperature (my variable), pH, Volume of Hydrogen Peroxide, Volume of Catalase solution, Concentration of Hydrogen Peroxide, Concentration of Catalase. When carrying out the experiment I must make sure that I keep all of these factors constant ('Control Variable'), apart from temperature, which is my 'Independent Variable'. pH is the level of acidity or alkalinity, pH affects enzymes because they are polar and the pH also has positive and negative charges, this works on the principal of "opposites attract", thus unfavourable pH can ...read more.


At low temperatures particles of reacting substances do not have much energy. However, when the substances are heated, the particles take in energy. This causes them to move faster and collide more often. The collisions have more energy, so more of them are successful. Therefore the rate of reaction increases. The more successful the collisions are the faster the reaction. Enzymes are specific in the reactions they catalyse, much more so than inorganic Catalysts. Normally, a given enzyme will Catalyse only one reaction, or type of reaction. The enzyme has an active site that helps it to recognise its substrate in a very specific way. Just like a key only fits into a specific lock, each enzyme has its own specific lock, each enzyme has its own specific substrate. This is called the lock and key theory. The enzymes never actually get consumed in the process; they just increase the rate of reactions. When enzymes denature the heat starts to destroy their shape and structure. The shape of the enzyme is so important to its working that any change in the shape of the molecules will make them less effective or stop them working completely. Therefore I predict that by heating the Hydrogen Peroxide, when it reacts with the enzyme the shape of the enzyme will be ruined due to the high temperature. ...read more.


After this I shall clear away the excess potato and start to set up my apparatus as shown above. Before starting the experiment I shall keep the test tube containing the pH and Hydrogen peroxide in the large beaker filled with the correct temperature, so that the hydrogen peroxide can adjust to the correct temperature. After I have done this I shall quickly place my potato sample in the test tube and place the bung on top so as not to loose the O2. This should now pass through the delivery tube and collect in the syringe. I shall time the reaction for 4 minutes and take a reading of how much O2 has been released. I will repeat this for all 4 temperatures, each time using a different sample of potato. It is important that I use the apparatus carefully, as safety will be an issue through out the whole experiment. I will wear goggles to protect our eyes. As we are using enzymes and Hydrogen Peroxide we need to be extra careful, ensuring they don't come in contact with our eyes and skin. I also must be careful when using hot water, being careful not to burn me. Therefore through out the whole experiment we shall be very careful in our actions around the lab. Austin Finnegan 3S ...read more.

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