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Investigation into one of the Factors that Affects the Rate of Enzyme Action.

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Investigation into one of the Factors that Affects the Rate of Enzyme Action Plan What is an enzyme? Enzymes are proteins that act as catalysts. A Catalyst is a chemical substance which speeds up the rate of reactions, but doesn't get used in the reaction itself. This is why catalysts are useful; they can be used many times over. The diagram below explains how enzymes break down food molecules: This diagram is known as the 'Lock and Key' diagram. This is because the food molecules fit perfectly into the enzyme, just like a key fits into a lock. Aim To see what affect increasing the enzyme Catalase has on oxygen production when the Catalase reacts with Hydrogen Peroxide (H2O2) Prediction I predict that as the concentration of the enzyme increases (i.e. more of the enzyme) then the amount of oxygen produced will increase too. I say this because the more enzyme molecules produced by a cell, the faster the reaction will proceed, because there are more reactive molecules for the hydrogen peroxide to react with. If there are more reactive molecules, then naturally there will be more of a reaction and therefore, the product (in this case oxygen) will be released quicker, and in higher quantity. Also, if we were to increase the substrate, in this case the hydrogen peroxide, then the amount of oxygen produced will also increase, provided that there are enough enzyme molecules to cope with the additional substrate. So basically, more collisions increase the rate of reaction, which in turn increases the amount of oxygen produced from the reaction. But this will only work up to a point. This is when a limiting factor occurs. This means that the volume of the hydrogen peroxide is not enough to react with a big increase in Catalase enzymes. Apparatus I will need the following apparatus to conduct my experiment: * 1 Trough (full with water) ...read more.


So whilst conducting this experiment, gloves should be worn, and type of dust mask should be worn, so you do not drink it ( or get it anywhere near your mouth) and also so you do not inhale the vapours. Laboratory coats should also be worn during the investigation to prevent chemicals from spoiling clothes. Care should also be taken whilst handling the chemicals as hydrogen peroxide is corrosive and the manometer fluid is permanently staining. Whilst using the razor blades, care should be taken to hold them by the handle and not the blade to prevent an accident occurring. Planned Observations I am planning to see how much of the oxygen gas is produced. The measuring cylinder which will be submerged under water will be full of water. I will take the reading of the cylinder. At the end of the experiment, I will take another reading. When I take this reading, I expect the amount of water in the cylinder to have dropped. This is because of the oxygen. The oxygen will bubble through the water, and 'push the water' out of the cylinder. From this, I can take a reading of the volume of oxygen produced. I am expecting the amount of oxygen produced to increase as the amount of the enzyme increases. Similarly, if the amount of the enzyme decreases, then the amount of oxygen produced should decrease too. I expect the graph of my results to look something similar to this: Modifications to plan Once I started conducting my experiment, I realized that I couldn't cut the potato slices at the exact measurements each time. So I decided to cut one, and use it as a template. I also noticed that the water in the cylinder that was submerged was never quite full. This meant that even though my thumb was covering the opening, the water was stick trickling out of the cylinder as I turned it upside down. ...read more.


Increasing the enzyme concentration further without increasing the substrate concentration has no effect on the rate of reaction which eventually will remain constant. Evaluation I think that under the circumstances, the experiment came up with fair results. With the apparatus I was working with, I think I obtained fairly accurate results, although the experiment could be made more accurate. From the line of best fit from the second graph labeled 'Graph With Line of Best Fit to Show Amount of Oxygen Produced' it is clear that some of the points do not exactly fit on the line. They are anomalies. Although they have only slight inaccuracies (except the last two, which could possibly be big inaccuracies), they are an indicator of possible errors in the investigation. These may have occurred in the measurement of the quantities of the enzyme and substrate. Another possibility was that fluctuations in temperature caused the rate of reaction to increase. Although minimal contact was made with the apparatus during the investigation, slight undetected variations in the room temperature may have led to inaccuracies. Possible Improvements/Alterations To create a more accurate experiment in the future, several precautions or alterations can be made: Instead of using potato slices that have slight variations in size, and volume of catalase, as a source for the enzyme, a 1 molar solution of the enzyme could have been diluted to create different concentrations. This way the concentrations can be measured far more accurately reducing the chances of errors in the investigation. In a future investigation, a far greater number of enzyme concentrations between those already recorded should be tested reducing the extent of any anomalies on a graph where the line of best fit must be drawn. In this investigation each reading was repeated so that an average rate of reaction for each enzyme concentration could be calculated. This could be improved by repeating the reading more frequently thus reducing the extent of any anomalies further, once averaged. Amardeep Sahota 11.18 GCSE Biology Coursework ...read more.

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