Inestigating the Affect of Yeast Concentration on the Breakdown

Investigating a factor that affects the rate of enzyme activity Enzymes speed up reactions. They have an area with a very particular shape called the ‘active site’. When the right molecule comes along (substrate molecule) it will fit perfectly into the active site and there will be a reaction. After the reaction the products then leave the active site. This process is often referred to as the lock and key theory as only one enzyme can carry out one type of reaction. The catalase enzyme speeds up the breakdown of hydrogen peroxide into oxygen and water.The hydrogen peroxide molecule acts as the substrate molecule and enters the active site where it is broke down into oxygen and water. The oxygen and water then leave the active site. Catalase enzyme Hydrogen peroxide (toxic) oxygen + water In the investigation I am doing, these are the factors I could change: * The concentration of the enzyme * Increase the temperature * Increase the PH I have chosen to investigate how the concentration of the enzyme affects the rate of reaction. I expect that the more concentrated the enzyme the faster the reaction time will be.Changing the concentration of the enzyme will affect the rate of the reaction. I predict that as we increase the concentration of the enzyme the faster the rate of reaction will be. I think this because as you add more catalase, the catalase will be able to break down more hydrogen peroxide molecules because there will be more active sites, however there will be a point where increasing the concentration of enzymes will be pointless as there will already be the same amount of active sites as hydrogen peroxide molecules.I predict that the rate of reaction with 20 catalase will be double that of 10 catalase because if you have double the catalase then they will digest the hydrogen peroxide twice as quick. Equipment * Small measuring cylinder 100ml * Pipette * 3 large beakers 200ml * Mini cylinder 10ml * Delivery tube and bung * Goggles * Bowl * Test tube * Test tube rack * Little beaker 50ml Preliminary method 1. Put on goggles 2. Fill 2 200ml beakers with 150 ml’s of water in each, one 200ml beaker with anything from 50-200ml of yeast and one 50ml beaker with 50ml of hydrogen peroxide. . Fill one large bowl full of water 4. Then, Place test tube rack on desk and place on test tube in it. 5. Next, fill a 100ml measuring cylinder with 100ml of water. 6. Put out a 10ml measuring cylinder and fill it with the appropriate amount of yeast and water according to your range using a pipette. 7. Place your hand over the top of the 100ml measuring cylinder, turn it over and place it in the bowl, trying not to lose too much water. 8. Place the delivery tube under the measuring cylinder. 9.Then add 2ml of hydrogen peroxide to the test tube using a pipette. 10. Measure the water in the measuring cylinder and record it and then quickly add the yeast and water to the test tube, place the bung in and start the stop watch. 11. At 1 minute record the water level again. 12. Wash the pipette using one of the beakers of water and then repeat the experiment with a different yeast and water ratio (remember to repeat them 3 times to make the results reliable). Oxygen produced Oxygen producedPreliminary results table Volume of yeast(cm3)| Volume of water(cm3)| Volume of hydrogen peroxide(cm3)| Time (s)| Test 1| Test 2| average| 8| 0| 2| 60| 12cm3| 9cm3| 10. 5cm3| 4| 4| 2| 60| 6cm3| 5cm3| 5. 5cm3| 1| 7| 2| 60| 1cm3| 0cm3| 0. 5cm3| From this practical I have decided on my range. My highest will be 8cm3 of yeast and no water and my lowest will be 1cm3 of yeast and 7cm3 of water. I have decided on these results because they have provided a sufficient difference between them and have a clear difference.