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Investigation: Enzymes

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Investigation: Enzymes BACKGROUND INFORMATION Aim To discover how temperature will effect the reaction rate between the enzyme Catalase and Hydrogen Peroxide. PROPERTIES OF ENZYMES * They are specific in their work; one enzyme speeding up one reaction only. * They are all proteins * Heat alters enzymes so they work at different rates. At certain high temperatures enzymes denature * They can be reused * They all require water before being able to function * Living cells are the only producers of enzymes. * They work within a narrow range of temperature. ENZYME CONTROLLED REACTIONS Enzymes are usually given a similar name to that of the substrate but ending in 'ase'. The reaction has two arrows because the reaction is reversible. If there is more maltose than glucose, the reaction will go from left to right and the other way round. How do enzymes work? Molecules are constantly active. When a substrate molecule bumps into a molecule of the correct enzyme, it fits into a depression (the active site) on the surface of the enzyme molecule like a key into a lock. The reaction occurs and then the molecules leave the site freeing it to react again with another substrate. If an enzyme is altered by heat, the shape of the active site is changed so that the substrate no longer fits. ...read more.


RESULTS These results below are the ones collected from the final experiment: Temp �C Time taken to collect 10cm� (s) Average Time (s) 10 236 255 251 247.3 20 165 181 154 167.3 30 90 97 86 91 40 52 60 57 56.3 50 122 143 286 183.6 60 / / / / 70 / / / / The result in read is anomalous and will be explained in my evaluation. This table shows the reaction rates of the experiment: Temp (�C) Volume of O2 given off Time taken Reaction Rate (1/t) 10 10 cm3 ? 247.3 seconds = 0.040 Secs-1 20 10 cm3 ? 167.3 seconds = 0.059 Secs-1 30 10 cm3 ? 91 seconds = 0.109 Secs-1 40 10 cm3 ? 56.3 seconds = 0.177 Secs-1 50 10 cm3 ? 183.6 seconds = 0.054 Secs-1 From this table above, the highest rate of activity is at the temperature of 40�C and these results show very clearly what I predicted earlier in my hypothesis. My hypothesis stated that the best temperature to keep the enzyme Catalase working at is 40�C and anything higher than this optimum temperature will decrease because the enzyme has denatured. My two graphs portray this theory clearly. The first one is showing the increase in the release of gas is affected by the increase in temperature and the second graph is showing the energy levels of the enzyme throughout the ...read more.


Investigation variations This experiment went very well overall, although the factors I have discussed above did not seem to accredit the method very well. The major weakness with the method we used was only the loss of gas during the process of connecting the bung to the conical flask this meant anomalous results could be recorded. The best way to solve this problem is not to adapt the current method, but to change it completely. I think that an alternative method of conducting this experiment would be to measure something other than the gas release. In laboratory, controlled conditions it is much easier to measure gas release but in a classroom, that certain method is unreliable. One idea is to measure the weight difference. This alternative method could be as follows: 1. Place a conical flask containing a fixed amount of Potato in onto the scales. 2. Take the weight of the flask and contents & add it to the weight of the fixed amount of H2O2. 3. Keeping the conical flask on the scales add the H2O2 to the flask. Every 10 seconds you can take the reading of the weight as it decreases on the scales. From this I can work out the weight difference.This difference will represent the content given off as gas and from this I can get a reaction rate, which is the goal I am aiming for. Biology Coursework 2002 Louise MacDonald 11MH ...read more.

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