Enzymes Experiment

Enzymes Experiment
Aim To find out the effect of raising the amount of enzyme on the breakdown of Hydrogen Peroxide. The Enzyme Enzymes control the speeds of cell reactions. They are referred to as catalysts. The enzyme I am using is Catalase, an enzyme found in potato. The substance that I will use which the enzyme will help to react is Hydrogen Peroxide (the substrate). Catalase is used to speed up the decomposition of Hydrogen Peroxide into water and oxygen. It can do this as the molecules of the Catalase and Hydrogen Peroxide fit together, and then the reaction can take place where oxygen and hydrogen is given off. Variables Substrate Concentration As I am changing the amount of Catalase available, I must keep the substrate the same to keep it a fair test. For instance, if the substrate was higher than usual, this might cause the oxygen to be released quicker as the enzymes? active sites have more places to work at. Temperature I will try to keep the temperature the same, at room temperature.
This is because as the temperature grows, the bonds which hold the enzymes? molecules together are broken. As this happens, the enzyme will fail to be able to connect to the substrate, so the enzyme will be de-natured and cease to work. Enzyme Concentration This will be the variable I am going to change. I will use different amounts of potato discs, ranging from 1 to 5 discs, which will therefore change the amount of catalase available. Prediction As the more potato discs I put in the tube, I am guessing more oxygen and water would be given off, and at a faster rate. I think this will happen, as more enzyme is being put in, there is more active sites to work on the substrate. As this is happening more oxygen and water will be given off, and will increase due to the amount of enzyme being offered to the H202 being higher, thus meaning that the H202 can decompose quicker. Though when the substrate starts run low, the reaction should slow down. Apparatus Manometer Hydrogen Peroxide Water Measuring Cylinder Potato Stop Watch Ruler Marker Pen Boiling Tubes Clamps Syringes Valve Method I will firstly, clean the work surfaces and check that all flasks / bottles / measuring cylinders etc. are clean and dry. I will set up clamps to hold the manometer and boiling tube. I will fill the manometer up with water, which I can use to observe how much oxygen has been given off (the fluid will move up). I will attach the manometer to the boiling tube where the H202, water and Potato will go into with a rubber bung. I will also make sure the air can flow through the other tube so the reaction doesn?t start earlier than I am ready to observe and take down the results. Next I will cut out the amount of discs I need; 15 in all, and put them aside on a clean tile. I will then measure out 25mls of Hydrogen Peroxide and 25mls of Water. I will then, when needed syringe 5mls of each liquid into the boiling tubes just before adding the potato. I will mark on the manometer where the water ends, and afterwards where it stops, which I will measure with the ruler to see the amount of oxygen produced. When the potato is put into the solution, the timer is started for 30 seconds, the air-flow tube is closed and the experiment will have begun. Once the 30 seconds is up, I will open the valve on the extra tube, which will then allow me to mark on the finishing line of the water in the manometer so I can take the distance the water was pushed up by the oxygen, thus telling me how much oxygen has being given off. Safety As safety is paramount in the lab, the following precautions were taken -
Care was taken when handling the Hydrogen Peroxide, as it is a
corrosive irritant. To avoid any contact with the skin, from the
bottle it was poured into a spouted beaker, where it could be
poured into the measuring cylinder safely.
Care was also taken with the razor blades used for cutting the
potato discs. These would have been handled by the large blunt
edge.
All used equipment / substances, was put in a ?dirty equipment?
tray which was specifically designated for a safe disposal of the
things used by the lab technicians.
Eye Protection was also used, as Hydrogen Peroxide is dangerous to
the eye.
Observations In the boiling tube, effervescence was observed. These bubbles were that of oxygen gas. Conclusion I found out that the reaction works faster when the more there is of the enzyme, where I went up to 5 potato discs. This must mean that at this enzyme concentration, there were most free active sites for the substrate molecules to react with. I found that the oxygen level given off consistently, though each time as you progressed, it rose by 0.5-1cm above the last value of potato discs. Thus meaning that the Enzymes much more effectively broke down the Hydrogen Peroxide when it was in large numbers. Evaluation I think the accuracy of the experiment was quite good, though there were some anomalous results. This can be seen on the graphs, where some of the points deviate from the line of best fit. These results could have happened due to temperature changes; if the temperature had risen then the pressure could have risen inside the tube, causing excessive gas to push the manometer water upwards more. Other reasons could be of personal error, whether in the measuring of the liquids, potatoes, time or the risen oxygen level. Improvements I did only go up to 5 potato discs; going up further could have uncovered the cut off point of enzyme action, when they stop working. Also, the fact of there being a wider spectrum would produce a wider field of results, so this would mean I could attain a better accuracy then with 5 discs. The discs could also of been weighed, and cut to a size where they were roughly equal, improving the accuracy of the results. I did the experiment 3 times and did encounter anomalies. Repeating the experiment 5 or 6 times and getting an average for all of those results would reduce anomalies further. Instead of using a manometer, which lacks the ability to measure the amount of gas inside it, only a change in whatever is being measured, a gas syringe could be used. This would mean the gas would flow directly into this cylinder and would be more accurate, as well as being able to find out the actual volume of gas given off. I could have also tested another variable, such as temperature. Raising the temperature would cause the enzymes to de-nature, and therefore I could have found the maximum operating temperature for catalase.

Enzymes Experiment 9.1 of 10 on the basis of 3026 Review.