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What effect does the pH have on the enzyme diastase? What effect does the temperature have on the activity of the enzyme diastase?

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Problem: * What effect does the pH have on the enzyme diastase? * What effect does the temperature have on the activity of the enzyme diastase? Hypothesis: * The optimum pH for the diastase enzyme to work will be at 37oC. The temperature of 10oC and 20oC are going to show that they are too low for the enzyme to function while the temperature of 70oC will show that it is a too high for the enzyme to function in. * The optimum pH for the diastase enzyme will be 7. The pH of 1 and 3 will be too acidic while the pH of 10 will be alkaline for the enzyme. Purpose: * To determine the effect of pH and temperature on the enzyme activity Materials: * 1% starch solution * Lugol's iodine * Buffer solution * 0.2% diastase * 4 test tubes * 2 hot plates * Ice * 5 dropper pipettes * Spot plate * Thermometer Procedure: A 1. The 4 test tubes have been labeled with pH numbers 1, 3, 5, 10 2. To each test tube 2 ml of the diastase solution has been added, followed by 2 ml of the respective buffer 3. 4 drops of the starch solution was placed into a depression on the spot plate, followed by one drop of iodine. The change of color was recorded. ...read more.


In this case, the starch was not catalyzed at all. Conclusion: * The optimum pH for the diastase enzyme is 7. The pHs of 1 and 3 are too acidic, while the pH of 10 is too alkaline. Ranking (best to worst): pH7, pH3, pH1 and pH10 * The optimum temperature for the diastase enzyme is 37oC. The temperatures of 10oC and 20oC are too low, while the temperature of 70oC is too high. Ranking (best to worst): 37oC, 20oC, 10oC and 70oC. Discussion: 1. Enzymes are protein catalysts. They consist of a long chain of amino acids that are held together by peptide bonds. Enzymes take part in breaking down the food materials into simpler compounds and speeding up chemical processed, which would otherwise run very slowly. It does so by reducing the energy of activation, speeding it forward and reversing reactions equally. Also, after catalyzing a reaction, enzymes are regenerated intact and ready to catalyze the same reaction again. When catalyzing a reaction, chemical change takes place when the bonds between reactant molecules break and a new arrangement of atoms creates bonds between the atoms of product molecules. For this to occur, reactant molecules must collide with enough force for the breakage to occur. Main function here is to catalyze a substrate in a chemical reaction. The substrate binds to a particular site on the enzyme to which is attracted, called active site. ...read more.


Due to the fact that an enzyme is a protein, its three-dimensional shape changes if the hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interactions that hold the polypeptide together in the tertiary structure, are broken by a medium with a higher temperature than the optimum. Once the enzyme changes, the active site loses its shape as well, and this way the substrate cannot bind with the enzyme anymore. Now that the enzyme cannot bind to the substrate, the chemical reaction is not preceded faster. As well, without enzymes, large molecules are not broken down (catalyzed) anymore. This is why it is important that the temperature of the body does not exceed 40oC. 7. Mammals and birds are warm-blooded organism. The advantages of homeostasis are that the organism can adjust to changes, for example in temperature and water availability, without the component cells being affected since they are having all their needs met by the internal environment. That is why some animals are able to exist at very cold surroundings like that South Pole and very hot environments like the deserts; it is due to the capability of controlling temperature. The internal environment makes it possible for the cells to work on certain tasks. For example, some cells work to maintain the optimum level of oxygen and carbon dioxide in the lungs. On the other hand, the cold-blooded animals take on the temperature of the surroundings. The only advantage here is that the chemical reactions are fast at a warm temperature, but once at a low surrounding, the rate of the chemical reaction slows down. ...read more.

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