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Investigate the effect of enzyme concentration on the rate of reaction.

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Biology Coursework- ENZYMES AIM: To investigate the effect of enzyme concentration on the rate of reaction. PREDICTION: An enzyme is a biological catalyst. They speed up the rate of a reaction however they do not affected themselves whilst doing this, which is why they are catalysts. Enzymes are made to be specific, this means that they can have only one substrate that they will work on. Each enzyme has an active site that is where their own specific substrate's molecule will fit into. However, having equal amounts of enzyme and substrate concentration still I think would not react as fast as it would if there was a higher concentration of enzymes, as each and every substrate molecule must react with an active site. Being equal amounts of each, until the substrate does not react with enzyme the reaction would not be complete and there would be a lower chance of a successful collision with an active site that is available. EQUIPMENT: APPARATUS AMOUNT REASON Boiling Tube 2 To hold the amylase and starch Boiling Tube Rack 1 To hold the boiling tubes and there contents. Iodine Indicator 1 Drop per Reaction Used as an indicator to determine whether the starch has been completely broken down. Amylase Concentrations ranging from 10% to 100% The enzyme used in this experiment to break down the starch Starch To stay constant using only 5ml The substrate used in the experiment to be broken down by the enzyme amylase Measuring Cylinder 1 Used to measure the amount of starch required. ...read more.


Both competitive and Non-competitive inhibitors will slow down the rate of reaction. Not aware of any SURFACE AREA A smaller surface area enables more successful collisions, as amylase and starch molecules as closer together, meaning there a higher chance of both molecules colliding with each other and therefore will give a faster rate of reaction. To make sure all experiments take place using boiling tubes and beakers with the same surface area. PRELIMINARY WORK: Before doing the actual experiment a preliminary test was done, so that a prediction could be made and notes can be made on what problems may occur. METHOD FOR PRELIMINARY TEST: 1. Set up all the equipment/apparatus as required in the experiment. 2. Using the pipette place one drop of iodine indicator into each well of the spotting tile. 3. Measure out 5cm3 of Starch using a pipette or measuring cylinder. 4. Measure out 1cm3 of Amylase using a pipette/measuring cylinder and put it into the test tube. 5. Add the 5cm3 of Starch to the test tube containing Amylase and start the stopwatch straight after. 6. Using the pipette, take out a little solution from the test tube and place in into one of the wells on the spotting tile containing iodine indicator every 30 seconds staring from point blank. 7. When there is no change in colour what so ever stop the stopwatch. ...read more.


3. Using the kettle you could not exactly be precise on the temperature of the water and have to repeatedly change it when it cools down. Temperature will affect the reliability of your results, bearing in mind that high temperatures would also denature the enzyme. Therefore, a water bath should be used as it can be kept at a set temperature throughout the experiment again giving you accurate results. 4. After the experiment test tubes could be contaminated, even if rinsed out therefore effect they next experiments results. To prevent this fresh, clean glass ware should be provided or time given to wash/ rinse the test tubes toughly. Enzyme concentration (%) Time taken for 1st attempt (s) Time taken for 2nd attempt (s) (*) Average (s) 100 90 137 114 0.008810572 80 114 269 192 0.005221932 60 179 216 198 0.005063291 Looking back at point 4, I have found an anonymous result shown on the results table in red, which I think is because of contamination from the previous experiment. Contamination can easily speed up the process, slow it down, have an odd result or have nothing at all happen, but in this case it has been slowed down and not following the trend. As an improvement changes I could make to my experimental method to carry out the same experiment are shown below: * Water bath instead of a kettle * Fresh, clean test tubes or extra time to have them cleaned * Syringes used instead off pipettes or measuring cylinder as they are more accurate. ...read more.

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