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Testing the effect of substrate concentration on enzymes

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THE EFFECT OF SUBSTRATE CONCENTRATION ON THE ACTIVITY OF THE ENZYME CATALASE INTRODUCTION Enzymes such as Catalase are protein molecules, which are found in living cells. They are used to speed up specific reactions in the cells. They are all very specific as each enzyme just performs one particular reaction or a small group of very similar reactions. They are very specific due to the fact that they have distinct structures, with which they attach themselves to their substrates therefore they cannot attach to other substrates that do not have such shapes (according to the International baccalaureate Biology text book, written by C. J. Clegg, from page 52 to 58). Many factors affect the rate of activity of enzymes. Such factors include 1.Temperature 2.Enzyme concentration 3.pH of substrate 4. Substrate concentration Catalase is an enzyme found in food such as potato, liver and yeast. It is used for removing Hydrogen Peroxide from the cells. Hydrogen Peroxide is the poisonous by-product of metabolism. Catalase is one of the most potent catalysts known. The reactions it catalyzes are crucial to life. Catalase catalyzes conversion of Hydrogen Peroxide, a powerful and potentially harmful oxidizing agent, to water and molecular oxygen. Catalase also uses Hydrogen Peroxide to oxidize toxins including Phenols, Formic Acid, Formaldehyde and Alcohols. Catalase speeds up the decomposition of Hydrogen Peroxide into water and oxygen as shown in the equations below. Formula: Catalase+ Hydrogen Peroxide---------------------->Water + Oxygen Catalase + 2H202------------------->2H2O+O2 It is able to speed up the decomposition of Hydrogen Peroxide because the shape of its active site matches the shape of the Hydrogen Peroxide molecule. ...read more.


294.4 35.7 27.5 19.82 RATE (cm3s-1) 0.000 0.034 0.280 0.363 0.504 Standard deviation 0.000 5.290 3.530 4.600 2.380 Example For trial one, the rate for the experiment with the 6% concentration of the H202 can be calculated as R = 10cm3 19.82 =0.504cm3s-1 QUALITATIVE DATA During the cause of the experiment, some data was collected which were not quantifiable, hence, were not written down in the quantitative data section. Below is a table containing those observations. Amount of bubbles produces during the experiment. As the experiment progresses, the amount of bubbles produced decreases from the higher concentrations to the lower concentrations. That is, in the order 6% > 4% > 2% > 1% > 0%. With the 1% concentration, It is observed that actual bubbles are not produces but rather, milder fizzing is observed in the boiling tube. With the 0% concentration, no bubbles at all were produces as the experiment progresses. Heat production The intensity if the heat produced during the experiment reduces as one moves from the higher concentrations to the lower concentrations. That is, form 6% > 4% > 2% > 1% > 0%. Just as with the bubble production, the intensity if the heat produced in the 1% concentration was vey low, and it didn?t stay for a long time, as it cooled down after a very short while. With the 0% concentration, no heat at all was produced as the experiment progressed. Where the reaction took place IT is observed that throughout the experiment, the reaction between the hydrogen peroxide and the liver catalase took place on the surface of the hydrogen peroxide solution since the bubbles was seen, and the heat was felt on the upper part of the boiling tube. ...read more.


Also, because different syringes were used, it took more time for some of the syringes to start moving because some of them were relatively tighter as compared to the others. Below is a table to illustrate the errors, how they affected the experiment and steps to improve upon it next time. ERROR EFFECT ON THE EXPERIMENT HOW TO IMPROVE ON IT NEXT TIME 1. The concentrations used Due to the minimal amount of concentrations used, the hypothesis could not be met in full since the later part which requested the reaction rate to remain the same was not observed More and higher concentrations of the solutions should be used in the next experiment. 2. Delay between adding the enzyme and the substrate, placing the stopper on the test tube and starting the stop watch This reduced the accuracy in the amount of gas produced in the given time One or more people should be invited to help out with the experiment so that the stopwatch, adding the substances and placing the stopper on the test tube will all be done simultaneously. 3. Limited number of trials in the experiment This takes a little from the validity of the experiment since conducting more trials will increase how valid the data obtained will be Run more trials in successive experiments for more data and validity of the experiment 4. The reaction started on the walls of the test tube hence some of the oxygen produced was lost This reduces the accuracy in the actual time taken to produce the actual amount of oxygen required. In further experiments, funnels should be used to transfer the solution from the measuring cylinder so that it will fall directly to the base of the test tube, without wetting the sides. 5. The difference in how freely the syringe moves. ...read more.

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