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Enzyme Coursework.

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ENZYME COURSEWORK PLAN Planning my Investigation I am trying to find out what affects the rate of reaction, when a 20 volume solution of Hydrogen Peroxide and a yeast suspension solution are mixed together in a conical flask. To measure the reaction I will count the bubbles of oxygen given off by the reaction, which will take place in a large beaker of water. The affect of the reaction is how much oxygen given off in a certain amount of time. An enzyme is a biological catalyst. They speed up the rate of a reaction but they are not affected themselves during the reaction. Enzymes are specific; this means that there is only one substrate that they will work on. Each enzyme has an active site. This is where their specific substrate's molecule will fit into and is broken down. Enzymes all work best at an optimum temperature. The optimum temperature is usually body temperature; this is approximately 37�C. If the temperature that the enzyme has to work at gets too high, it will start to become denatured and therefore it will no longer work on its substrate correctly as the active site has changed shape. Enzymes also usually work best at an optimum pH level. This is approximately pH 7, because enzymes are proteins, which are damaged by very acidic or very alkaline conditions, pH 7 is the perfect temperature. Yeast is a living micro organism. Yeast produces many enzymes. Enzymes are not living they are protein molecules. One enzymes produced by yeast is catalyse. Yeast is mainly used for two processes. ...read more.


I will measure out the 15 CCs of Hydrogen Peroxide by using one of the syringes. From the small conical flask I will measure out 1 CC of the yeast suspension solution. I will mix the yeast suspension solution before I measure it out using the other syringe. I will do this because as it is a suspension, it could be denser because of the living cells at the bottom than the top, so I will stir the solution well. All of my measurements will be made as precise as possible to keep the experiment accurate and fair. The next thing that I must do is to put the delivery tube and bung together and place the delivery tube, with the glass 'V' shaped tube on the end of it. These two pieces of apparatus will be placed at the bottom of 500ml of water in the beaker. I will connect the syringe of yeast suspension solution to the syringe connector on the bung. Once this is connected I will add the yeast solution into the large conical flask, which contains the Hydrogen Peroxide. As soon as I started the reaction I will start the stopwatch. I will count the number of oxygen bubbles that are given off in the first 30 seconds, as this the my time I have allowed myself to count the bubbles to make it a fair test. I will record my results in a table, so I can compare them to my other results. I will carry out every experiment I do three times, so I can get a range of results for each experiments. ...read more.


I did get one result which was abnormal, but I put this down to the lack of my accuracy. The results I got were what I wanted, so I am happy with them. The experiment could have been made more accurate by using other ways of doing things that were important to the experiment. More accurate measurements could have been perfected by not using measuring cylinders, which were only to either 0.5cm� or 1cm� degree of accuracy. This is not very accurate. I would use a gas syringe, which measures much more accurately, could have solved this problem. Another inaccuracy was when we cleaned out the measuring cylinders, they could of still contained some Hydrogen Peroxide, water or yeast. This would give that test either an advantage or a disadvantage. I know that the temperature can effect the rate of a reaction. The temperature was not the same on both days, as one of the days was hot, and the other overcast. So this may have changed the results slightly. The enzymes may have denatured in some experiments because of the yeast solution could have been uneven. So some heavier enzymes could of sunk to the bottom and lighter enzymes as the top. I stirred the yeast suspension solution to solve this problem, but maybe using fresh yeast could perfect the results furthermore. Making sure that the oxygen bubbles were inside the allowed time of thirty seconds was difficult, having an adjudicator to calculate too could help in this problem. The more different concentrations of Hydrogen Peroxide would prove the whole experiment was correct without a doubt. Another thing to be done would be to do more repeats for each concentration. This would make results more accurate when finding averages. ...read more.

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