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The main aim of this experiment is to investigate how varying the concentration of an enzyme will affect the activity of the enzyme trypsin in milk.

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THE FACTORS AFFECTING THE RATE OF REACTION BETWEEN THE ENZYME SOLUTION AND THE SUBSTRATE. AIM The main aim of this experiment is to investigate how varying the concentration of an enzyme will affect the activity of the enzyme trypsin in milk. Equation Enzyme + Substrate Product (s) + Enzyme. Background Knowledge. Enzymes are biological catalysts; therefore they speed up the rate of reaction in cells. Enzymes have a tremendous effect on biochemical reactions, and these reactions would take place at a very slow rate if it weren't for these enzymes. Basically an enzyme is a catalyst that speeds up reactions faster tan they would normally be at. Enzymes are proteins and are made up of a long chain of Amino Acids. These amino acids are strung together like beads on a necklace, and they are then folded to make very complicated shapes and sizes. Each chemical reaction has its own specific enzyme that controls it. Therefore, only a single enzyme is used to speed up that reaction. A basic summary of enzymes' characteristics. i) Catalysts- Substances that speed up chemical reactions. These reactions do not change the catalyst. So, even small amounts of an enzyme can do a big job. ii) Protein- Whose chemical; shape is special to the substance it works on. iii) Specific- Protein alone fits into the chemical shape of the enzyme; protease', not starch or anything else. So, protein alone is digested by it. iv) Temp. Sensitive- Boiling destroys enzymes by altering their shape, cooling only slows down their reaction. v) pH Sensitive- Each enzyme has its own preferred (optimum) pH. The enzyme that we are going to be using is called 'Trypsin' and it is a protease enzyme. It digests a protein called 'casein' Casein is what makes the milk become opaque. In our experiment we will add trypsin, and this enzyme will break down/ digest the casein into Amino acids, consequently the milk will become clear. ...read more.


This simply means that at high concentrations there will be a greater possibility of 'trypsin' molecules colliding with the milk, and therefore reacting. These reaction rates are explained using the collision theory, which states that a rate of reaction depends on how hard and how often the reacting particles collide with one another. Particles have to collide hard enough to react. As you can see from the diagrams above that at a high concentration the particles are more likely to collide with one another than, a solution of normal or low concentration. These diagrams hopefully demonstrate the collision theory. I basically believe that when the concentration of enzyme solution is increased, the rate of reaction will also increase. In this experiment, as the trypsin is added to the milk there are numerous collisions with the casein, caused by kinetic energy. When the trypsin later collides, it causes an active site. The product, which in this case is the substrate molecule (milk) is forced onto the enzyme molecule. As this happens, trypsin (enzyme solution) eventually produces amino acids, which are soluble in water, and that is what makes the milk become clear. Nevertheless, the rate of reaction should decrease as the experiment develops, i.e., when the concentration of trypsin decreases. This can be explained by the fact that when there is a small concentration of trypsin, there are fewer particles with the required activation energy (EA). This basically means that there are fewer particles to collide with one another, slowing down the reaction as a whole. Therefore I can clearly predict that the percentage of trypsin will be indirectly proportional to the time taken for the casein to be digested. I also predict that the increase in concentration of the enzyme solution will be directly proportional to the increase in reaction rate. Dilutions of the enzyme solution. Percentage of enzyme solution (cm3) Percentage of distilled water (cm3) ...read more.


2. I believe that the method used to find out when the end point determination method had its limitations because; you have to keep an eye on each and every test tube that has enzyme solution and milk in it. There are three reactions to do for each concentration and five concentrations. So, it becomes humanly impossible to be punctual when you can see the black ruler, because there are so many experiments taking place at the same time. If I were to extend the experiment further in the future, I would possibly repeat the experiment, using a similar method, but with a greater number of concentrations. This is because in my experiment I only used 5 different concentrations of enzyme solution. Next time I could possibly use concentrations of 2.0%, 1.5% or 0.2%, 0.4%, 0.6% etc. I could possibly even vary the concentration of the substrate (casein). By doing this, I would be able to discover a connection between the enzyme solution and the substrate. When the experiment is carried out again in the future, to improve the reliability of the results, I believe that it is necessary that various factors be considered. Although no obvious anomalous results were produced, there may have been some external factors, which affected the reliability of the data. The 1st being the temperature of the surroundings. The temperature of the experiment has to be left constant because if that changes then it will affect the rate of reaction greatly, which will have detrimental effect on the experiment and especially on the reliability of the data. In the future it is necessary that the temperature is kept constant, so, next time if I do this same experiment I would keep the test tube in a water bath. In this way the temperature would stay constant. In conclusion, both my initial predictions were correct and the actual theories behind the predictions were correct. The higher the percentage of enzyme solution, the time taken for the substrate to be digested would decrease. ...read more.

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