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Pepsin pH Experiment

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Pepsin pH Experiment After finishing the practical section of this experiment, I recorded all the results in a table and constructed two graphs. One of the graphs represents the rate of the reaction on the vertical (y axis), and the pH on the horizontal (x axis). The other graph I drew, shows the time in seconds on the y axis, and the pH on the x axis. Table of results: Solution Tube Time 1 9:31 2 5:20 3 2:05 4 2:37 5 2:29 6 2:39 7 4:15 8 6:04 9 13:30 10 denatured When I had collected in all of the times, I converted them into seconds in order to finally find out the rate of the reaction. The process by which this is accessible is done using the following technique- rate = 1/time in seconds (x constant (10,000)). When I had finished the conversion I constructed another table. Table of results: Solution Tube Time in secs Rate of reaction 1 571 17.5 2 320 31.5 3 125 80.0 4 137 73.0 5 149 67.1 6 159 62.3 7 255 39.2 8 364 27.5 9 810 12.3 10 denatured dentaured Once I had calculated all of the rates for each solution tube, I was able to construct the two line graphs. ...read more.


From the line of best fit on both graphs, it is clear that some of the points do not exactly fit. They are anomalies. Although they have only slight inaccuracies, they are an indication of possible errors in the investigation, there could be many reasons for this, for example, maybe I measured out the acid to a slight differential volume than was expected, but these things are only minute. As long as you can see the general pattern that arises, then a general conclusion can be formed. The measurement of the time taken for all of the egg suspension to disappear is probably the most likely to cause an interference in my final results. Another example could be that there was a slight temperature fluctuation which could have caused the reaction rate to increase slightly. There are some suggestions and improvements which can be made, and these are for example, to procede with only one solution at a time, this would make the overall experiment much slower, but you would be able to obtain better and more reliable results, especially when you have the chance to concentrate on one tube in the water bath, making the time taken for the reaction to take place much more reliable. ...read more.


It was noticeable that in the final solution in the experiment, the enzyme had denatured, resulting in there being no change in the solution. Enzymes, like other proteins consist of polypeptide chains held together in a particular position by cross-links. When an enzyme is dentaured, the cross-links are broken and the polypeptide chains open up and become randomly arranged. As a result the protein loses its normal shape and becomes biologically inactive. Dentauration is brought about by heating, excessive amounts of certain chemicals, or in this case but extremes of pH. Overall it has been proven that there is a particular pH which is 1.3 in this case, it may be slightly either side of this, so that in itself is a minor error, which provides us with the optimum rate of reaction. The results are generally quite reliable, the procedure was of a good standard for experimentation, although the experiment could have been carried out a few more times to ensure fairness and an average reaction rate. Obviously there is also the bug in the set-up, which is the denaturation of solution ten. This is something which can be recorded and then adjusted to find out what the highest pH the reaction will occur at. ...read more.

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