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Enzyme Concentration and Enzyme Activity Aim: The pancreatic duct in individuals who have cystic fibrosis frequently becomes blocked, reducing or preventing the release of pancreatic enzymes into the small intestine. The aim of this activity is to investigate the effect of a reduction in enzyme concentration on the rate of reaction, in this case the breakdown of sucrose by sucrase enzymes. Hypothesis: I predict that an increase of concentration levels of substrate will catalyse the rate of reaction up to a point whereby any further increase in concentration produces no significant change in the rate of reaction as result of the enzyme reaching their active peak. Null Hypothesis: There will be no relationship found between the concentration levels of enzyme and substrate and the rate of reaction. Rationale: Enzymes play key roles in an experiment where they are used to catalyse a reaction. Enzymes can speed up the breaking down of molecules, like protein, into smaller ones. Others can speed up the building of large molecules out of small ones. They do this by lowering the energy needed for the chemical reaction to occur, the energy needed for the chemical to occur is also known as the activation energy. Without the enzyme, the activation energy needed for the reaction to proceed is high and vice versa. ...read more.


The enzyme can also be affected by the pH, if it's too high or too low the active site will, again, change shape, resulting in a lower rate of reaction.T Method: - Equipment list: - * Standard acidified sucrase solution. * Gelatine jelly. * Standard laboratory glassware, beakers, test tubes etc. * A ruler * Stop clock * Thermometer * Pen and paper. Variables: - * Independent variable: - My independent variable is the different concentrations of substrate. * Dependant variable: - My dependant variable for this experiment is the measurement of the rate of reaction in different concentrations. * Control variables: - My control variables are the variables that I need to keep the same to make sure that this experiment is a fair test. These are: - 1. The temperature. It is important that I control this as this will denature the enzymes. 2. pH. It is important that I control this as this will denature the enzymes. 3. Time that the mixture is in the beaker before and during the experiment. Procedure 1. Half fill a glass beaker with water to act as a water bath. Adjust its temperature to between 35 C and 40 C. (Note: Using a Bunsen burner may force the temperature of the water to rise a few degrees above the stated temperature after the burner has been taken away.) ...read more.


Results Test tube Sucrose Concentration / g dm3 Time (secs) Observations A 5 363.6 Light green B 10 87 Light yellow C 15 76.2 Yellow D 20 67.2 Light Orange E 50 45 Orange F 100 44 Orange/Red Below are the relative rates of cloudiness formation. I have worked this out by dividing 100 by the time taken in seconds for each tube as follows: Relative rate of cloudiness formation = 1000 T Test tube Sucrose Concentration/ g dm3 Relative Rate of cloudiness. A 5 2.75 B 10 11.49 C 15 13.12 D 20 14.88 E 50 22.22 F 100 22.73 Graphs Conclusion In this experiment, my results show that as the concentration of sucrose increases then the rate of reaction decreases. This suggests that as an increase in substrate is added the enzymes can not catalyse these as they have reached their active peak. The graph shows this as a steady curve. This then backs up my hypothesis and disproves my null hypothesis. Evaluation To improve this experiment I would have to increase the number of tests to see if my results are repeatable and accurate. I would also want to make sure that the timing was quicker when adding the Benedict's solution so that each tube would get the solution in a much shorter time to avoid anomalous results. I would also take more care when conducting the experiment to ensure that there can be no random errors produced. ...read more.

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