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Investigation into the digestion of milk by Trypsin.

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Investigation into the Digestion of Milk by Trypsin Background Knowledge To investigate the effect of trypsin on milk a number of separate experiments will be performed whereby milk is digested by trypsin under controlled conditions. Specific variables will be changed by calculated amounts to gauge their individual effects on the rate and amount of reaction that occurs. Trypsin is a biological catalyst, (a substance that speed up a reaction without being used up or changing the reaction in any way), known as an enzyme that is found in the human body. Trypsin is a protease enzyme, which means that it digests the proteins in food that is consumed. However humans, (as animals themselves) are constructed largely of proteins. This means that unless stopped trypsin produced in the pancreas would digest the proteins that make up the body itself, and indeed all of the body's enzymes as well as the proteins digested in the digestive system. This is why trypsin is not produced in its active form. Trypsin is produced in the pancreas and is secreted in the form of trypsinogen. Trypsinogen is inactive until it comes into contact with another enzyme, enterokinase, (an enzyme that is secreted by the lining of duodenum). Enterokinase activates the Trypsinogen by converting it into trypsin so that it can digest food that passes through the digestive system. Trypsin breaks down proteins by separating the long chains of amino acids that form the proteins into smaller ones. This occurs when a Trypsin enzyme comes into contact with a protein. It is believed by scientists that the enzymes function by fitting onto substrates, (because of a specific shape an electric change they bear) and undergoing reactions to split or link the substrate. As contact is needed for enzymes to react with substrates the impact theory, (which states that reactions occur when substances bump into each other) suggests that the higher the temperatures at which substances are left to react with each other, the greater the chance of reaction, therefore the faster the rate of reaction. ...read more.


This will be long enough for enzymes to fully denature. Preliminary work shows that Trypsin enzymes will not denature at 60 degrees Celsius. This being the case a new water bath will be set up at 80 degree Celsius. This will ensure that results from the experiments show fully the effects of heat upon enzymes such as Trypsin. After 5 minutes the stop clock was reset. All of the trypsin was then poured into the milk solution, (it is important that this is done in one go as otherwise some of the trypsin will not be reacting for as long as that poured into the milk solution first). The timer was started and the test tube containing a mix of both solutions was then placed back into the water bath. The appearance of the solution was closely monitored. When the reaction was over the stop clock was stopped and the time taken was recorded. The end of the reaction was signalled by the milk and trypsin solution turning transparent. This however was not an accurate way of measuring if the reaction had totally finished, as the solutions in my preliminary experiments never went completely clear. This is why I decided to use a more comprehensive test. A protein test can easily be carried out by mixing up a solution of 5 cm^3 of sodium hydroxide and 5 cm^3 of 1% copper sulphate. This solution was the placed in the dips of a dimple tray. As the reaction start to end, (when the milk starts turning transparent), a pipette can be used to drip a single drop of the trypsin milk solution onto the indicator solution. If there is still protein in the solution the indicator will turn purple. Only when all the protein is digested, (the end of the reaction), will the solution not turn purple. At this point the time should be recorded, as the reaction has ended. ...read more.


Due to the protein test not working another system was employed whereby the transparency of the solution was gauged by observation. This meant that there was a larger error margin as to the definition of when the experiment had finished. Though this effected the accuracy of the results recorded I believe that the conclusions drawn were still accurate, as there was a large time difference between the results from the different temperatures that could not be mistaken even if the results were only accurate to the nearest 10 or 20 seconds. I believe that my results show no anomalies, as the results shown on my graphs show simple trends with no obvious exceptions. Due to this continuity of results, (drawn from my graphs), I believe that my findings are accurate enough to base my conclusions upon. I believe that the investigation could be further explored by experiments being performed at 10 degrees Celsius temperatures intervals ranging between 0-80 degrees Celsius. This would help to verify trend in the results and would show to a greater degree of accuracy the exact temperatures at which the reactions cease to occur. The results would show more accurately how steep the curve from the optimum temperature past the point of denaturisation to the point where the reaction doesn't occur is. This would show more accurately the temperature at which the reaction stops occurring. Equally the point at which the trypsin is dormant, and does not react at could be ascertained to a higher degree of accuracy. The investigation could also be furthered by performing the same experiment, under the same conditions on natural enzymes, thus showing how the optimum temperature and point of denaturisation differ between the 2. The effects of Ph upon trypsin enzymes and the effects of the concentration of both the milk solution and the trypsin solution could also be investigated. I believe that the investigation of these factors would help to illustrate how enzymes are specific about the environment in which they operate in, and how minor changes can effect the rate at which trypsin digests the proteins in milk solution. ...read more.

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