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Investigating the effect of a chosen factor on the activity of Lipase

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Investigating the effect of a chosen factor on the activity of Lipase Aim: To explore the action of Lipase and Bile salts on lipids at different temperatures, and assess their roles in digestion. Theory, Hypothesis and Prediction: In nutrition, intake of lipids is necessary to form a source of energy storage, i.e. Fats. But as the lipid molecule is highly hydrophobic, it needs to be broken down first to fatty acids and glycerol to be taken in efficiently. As the diagram? shows, there are three fatty acid tails present in the lipid molecule, so it can diffuse quite freely through the plasma membrane, yet it needs to be broken down nonetheless so that it can be taken up readily through the walls of the digestive tract, to be transported to the areas of the body where it is used to form lipids again, for either: * Deposition as fat (energy storage) * Formation of cholesterol * Formation of steroid hormones (e.g. testosterone) * Formation of phospholipids for plasma membrane construction, or * Immediate respiration as energy molecules. The break down of lipids into their constituent molecules is a four-stage process and begins in the stomach and continues into the small intestine: - 1. ...read more.


1. Make up four solutions, containing: - a. 2cm� of Bile salts and 2cm� of Lipase solution b. 2cm� of Bile salts and 2cm� of distilled water c. 2cm� of Lipase solution and 2cm� of distilled water d. 4cm� of distilled water (control) 2. Into each solution, add 2cm� of 0.2 moldm�� Sodium Carbonate solution, and 2cm� of Phenolphthalein indicator 3. Place these in the water bath set at 40?c for 5 minutes so that the contents are all at the same temperature. 4. Add to each a small and equal amount of butter. 5. Note the time taken for a solution to change colour, from purple/pink, to colourless. 6. Repeat 5 times for accuracy. 7. The solution that consistently lost its colour the fastest is the optimum conditions for metabolism of lipids, and this will be used in the main experiment. The solution that should change colour most rapidly is the mixture of Bile salts and Lipase solution, so this will be used in the main experiment. Results and Conclusions drawn from Preliminary Experiment: 1. Bile and Lipids do indeed need to be in the reaction mixture together for optimum rate of reaction - the alternative hypothesis proved correct. ...read more.


c. Add 2cm� of bile salts and 2 cm� of Sodium Carbonate solution. 2. Place these in a water bath set at 40?c, and leave for 5 minutes so that the contents will become thoroughly mixed and uniformly reach the temperature of the water bath. 3. Measure the pH of each tube at (this is the reading at zero minutes). 4. Note:- before carrying out the next step, it is advisable to stagger the addition of butter in each solution by 30 seconds so that when readings are being taken it is easier to retain an accuracy, as otherwise all the readings would need to be taken at the same time, which is simply impractical and will lead to many inaccuracies and difficulties. 5. Into each solution add a small and equal of butter, and using a pH meter record pH changes in each mixture every three minutes for 18 minutes 6. Record the results 7. Repeat six times for accuracy. 8. Statistical analysis: Average all of the readings and construct a graph to show the data. Carry out the t-test to ensure that the data is consistent and that there are no results that have a significant deviation from the data range. ...read more.

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