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Investigating the Effect of Substrate Concentration on the Rate of a Catalyse Reaction- plan

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Investigating the Effect of Substrate Concentration on the Rate of a Catalyse Reaction. Plan Introduction Enzymes are biological catalysts they speed up the rate of reactions. They are globular proteins, which have a complex 3-dimensional shape. The substrate fits into the active site of the enzyme. The enzyme action is more dynamic than believe previously; the induced fit theory means that the substrate enters the active sit of the enzyme then changes its shape slightly to hold the substrate. The substrate fits in to enzyme by electrostatic attraction. Sometimes products can be broken down, and other times two substrates bond together to fit in to the active sit. These are called catabolic and anabolic reactions respectively. Enzymes are never used up, but they can be used to catalyse further reactions. I have chosen to investigate the breakdown of hydrogen peroxide into water and oxygen, by the enzyme catalyse. Hydrogen peroxide catalyse water + oxygen 2H2O2 catalyse 2H2O + O2 I have chosen to investigate this equation because a gas is produced which is easier to measure when collecting needed data. Enzyme reactions rely on successful collisions between enzymes and substrates. Increased temperature results in increases kinetic energy. Every 10?C rise in temperature results in kinetic energy, therefore doubling the rate of reaction. ...read more.


But if temperatures decrease the rate of reaction will decrease as there is less kinetic energy therefore fewer collisions between substrate and active site will take place. To look at the effect of temperature on the gas produced I carried out the same experiment as before using a Ph 7 buffer. I used 10 potato slices for this experiment. Time (secs) Vol. gas (cm�) 10 0.02 20 0.12 30 0.2 40 0.26 50 0.32 60 0.41 20?C Time (secs) Vol. gas (cm�) 10 0.65 20 1.32 30 2.0 40 2.7 50 3.35 60 4.0 30?C Time (secs) Vol. gas (cm�) 10 0.9 20 1.8 30 2.7 40 3.55 50 4.4 60 5.2 40?C Time (secs) Vol. gas (cm�) 10 0 20 0.05 30 0.1 40 0.15 50 0.2 60 0.22 55?C The temperature that produces the most oxygen in the quickest time is 40?C. But this temperature is difficult to maintain. As the second quickest temperature for the production of gas is 30?C, and this is around room temperature s o will be easiest to maintain. As the temperature increases the particles have more kinetic energy and so more collisions will occur increasing the rate of reactions. This will occur only up to a certain point where the enzymes begin to be denatured. The collisions have sufficient energy (activation energy) ...read more.


In this way a gas syringe is much more accurate. Also to make the experiments more reliable I will repeat the experiment three times, so that the anomalies can be filtered out. I have decided from my preliminary work to collect the volume of gas collected every 10 seconds; these intervals will be accurate as I am using a stopwatch. I will be able to depend more on my results if I repeat the experiment and I collect the same results. Risk Assessment When making cylinders with the cork borer be sure not to put your hand on the other side of the potato as the borer may cut tour hand as it comes through the other side. When slicing the clingers using a knife on the tile the potatoes will be slippery so be careful at all times, holding the cylinder firmly so that it does no slip, otherwise you may cut yourself. And when not using the knife, put it out of the way at the back of the bench. Hydrogen peroxide is corrosive. It is dangerous if swallowed, it causes serious internal damage due to the release of oxygen. If swallowed the mouth should be washed out with water. Cuts on hands should be covered as it will make open wounds sting. Eye protection should always be worn so it will not come into contact with the surface of the eye. ...read more.

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