How pH Affects the Break Down of Starch by the Enzyme Amylase Essay

How pH Affects the Break Down of Starch by the Enzyme Amylase Hypothesis: The optimum pH for the reaction of starch with amylase is pH 7. PH values lower or higher than this value will result in a slower rate of reaction. Amylase works in the range pH 3 to pH 11. Biological Knowledge ==================== PH changes affect the structure of an enzyme molecule and therefore affect its ability to bind with its substrate molecules. Changes in pH affect the ionic bonds and hydrogen bonds that hold the enzyme together, which naturally affects the rate of reaction of the enzyme with the substrate. On top if this, the hydrogen ions neutralise the negative charges of the R groups in the active site so that the substrate and the active site do not attract and therefore do not react. The optimum pH for most enzymes is pH7. In the body, amylase works mainly in the small intestines, where the acidity from the stomach has been neutralised by the hydrogencarbonate ions in the pancreatic juices secreted by the pancreas. Therefore, it follows that if amylase were adapted well to the surroundings which it is found most commonly at, it would work best in neutral conditions, which is pH 7. To allow for fluctuations in pH, amylase would need to work from around pH 3 to pH 11. Apparatus Apparatus Reason/Reference to pilot study Colorimeter Values can be obtained measuring the breakdown of starch, instead of just the colour when the iodine solution is added. If not much starch is broken down, iodine will colour it blue/black so a low % Transmission will be obtained. If a large volume of starch broken down, iodi... ...ially used 3 cm ³ of distilled water with 3 drops of iodine. It then occurred to me that this was inaccurate, as amylase solution is cloudy. Therefore, I blanked it with 2 cm ³ water, 1 cm ³ amylase and 3 drops of iodine. I decided to experiment with pHs within the range pH 2 to pH7, as I discovered that pH 4 is the optimum pH, instead of my predicted pH7. Risk Assessment  · Wear goggles to protect eyes from iodine solution  · If spilt on clothes or skin, wash with water to prevent harm to the body  · Keep iodine bottle away from edge of table to prevent injury from broken glassware Ethical Implications The amylase solution is taken from an animal. The owner of the animal must permit this act. The animal's body must be paid respect when the enzymes are removed so must therefore be treated carefully.