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This is an investigation to determine the effect of concentration on the activity of an enzyme Trypsin on the insoluble protein found in milk known as Casein.

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Title: AS Biology Coursework Aim This is an investigation to determine the effect of concentration on the activity of an enzyme Trypsin on the insoluble protein found in milk known as Casein. Introduction Casein is an insoluble protein, found in milk as a suspension of particles, which are held together by calcium ions. It forms a white or cloudy precipitant. In the structure of casein, there are no disulphide bridges. Therefore, it has a relatively small secondary and tertiary structure. As a result, it does not denature quite easily. Furthermore, the hydrophobic groups found on the outside of protein make it insoluble in water. When a suspension of casein is hydrolysed, it becomes cloudy at first and eventually clearer when the product is dissolved. This Hydrolysis Reaction is catalysed by Proteolytic enzyme such as Trypsin. Trypsin is a digestive protease. It is produced by the pancreas and works in the small intestine, where it breaks down proteins to polypeptides and into amino acids. * Dependent Variables > Enzyme and Substrate Temperature > Buffer Solution > pH * Independent Variable > Enzyme Concentration * Confounding Variables > Enzyme and Substrate Temperature The rate of an enzyme controlled reaction is measured upon the substrate used or the products formed over a period time. Increasing the temperature causes more heat energy, which makes the substrate molecules and enzymes move a lot faster. ...read more.


* Trypsin Concentrations Trypsin / cm� Distilled Water / cm� Concentration / % 5 0 1 4 1 0.8 3 2 0.6 2 3 0.4 1 4 0.2 * Interpretation of Results I have completed the practical part of this assignment and have entered the collected data into my table of results. By examining the set of results I have acknowledged a certain pattern to appear between the time taken for the saturation of casein, with the concentrations of enzyme trypsin solution. The greater the concentration of enzyme trypsin solution, the less time it will take for the casein solution to clear. > Evidence from the Collected Data Trypsin Concentration/% Average Time Taken/sec 1 0.61 0.2 424.80 > Set of Results Casein/% Trypsin Vol./cm� Distilled Water Vol./cm� Enzyme Conc./% 1st Reading Time/sec 2nd Reading Time/sec 3rd Reading Time/sec Average Time/sec 2 5 0 1 0.56 0.66 0.62 0.61 2 4 1 0.8 139.20 149.40 151.80 146.80 2 3 2 0.6 213.00 251.40 256.20 240.20 2 2 3 0.4 320.40 272.40 327.60 306.80 2 1 4 0.2 390.60 436.80 447.00 424.80 My set of results show a very similar correlation between the enzyme trypsin concentration against the time taken for the casein solution to clear. The enzyme trypsin will break down the casein molecules and allow it to become soluble and transparent. ...read more.


* Systematic Errors Systematic errors are inevitable and produce inaccuracies that are similar and consistently in the same direction. Systematic errors are often problems which continue throughout the entire experiment. Systematic errors are difficult to detect and cannot be analyzed statistically, because all of the data is off in the same direction. It is either to high or too low. Spotting and correcting for systematic error takes a lot of care. * Other Experimental Errors and Uncertainties I believe that the pH of the buffered solutions such as casein/trypsin changed and was unable keep the pH constant. Therefore the enzyme could not resact with the casein molecules. It is also very difficult to judge when all of the casein has become soluble. There will always be a difference in the timings recorded. Therefore, a colorimeter can be used to accurately judge when all the casein has been dissolved. It is an apparatus that characterizes colour samples to provide an objective measure of colour characteristics. The colorimeter allows the absorbance of a solution at a particular frequency of visual light to be determined. The way to achieve the most accurate results is to use the most recently made buffered solutions, measuring them using the correct and clean apparatus, allowing the reaction to take place in a clean test tube washed by distilled water and record the time it takes for the casein solution to clear by holding it up to a bright light and verify transparency. ?? ?? ?? ?? ...read more.

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