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Investigation on enzymes.

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Introduction

Investigation on enzymes I am going to be conducting an investigation on lipase and bile; and the affect they have in fat digestion. Enzymes are biological catalysts that speed up reactions in living things; and chemically change the substances it is breaking down. They are made of amino acids and made in living cells. The enzyme I will be investigating is Lipase. Lipase is an enzyme that helps in fat digestion by breaking down fat into fatty acids and glycerol. Fat is the substrate of Lipase. Lipase is created in three places, the pancreas, the stomach and the salivary glands. The other substance that helps in fat digestion is bile. Bile is not an enzyme, as it does not chemically change fat, it breaks it down by the process of emulsification. This decreases the surface are of the fat, making the job lipase has to do, much easier. Bile is created in the liver. Planning I will be investigating how bile affects the time it takes for lipase to break down fat. The fat will be represented by milk. The possible variables that would affect fat digestion are: - * The amount of lipase * The amount of bile * The amount of milk (fat) ...read more.

Middle

Decide what concentrations of bile and water are going to be used (see mine below) and make them using a 1 ml syringe. 2. Add 2.5 cm of milk (the fat) to each concentration using a 5 cm syringe. 3. Add each 0.5cm of each bile solution to each test tube. With a marker pen, clearly mark each test tube with the percentage of bile solution. 4. Add 3.5cm of Sodium Hydrogencarbonate (the alkali) to each test tube using a pump burette. 5. Add 3 drops of Phenolphthalein (the indicator) to each test tube and shake so the whole solution is pink. 6. Put each test tube in the water bath, set to your chosen temperature and leave for ten minutes so the whole solution is at the right temperature. 7. Add 0.5 cm of lipase to 2 test tubes and start the stopwatch. 8. After two minutes add 0.5 cm of lipase to another two test tubes and repeat until every test tube has lipase in it. 9. Take down the time that each test tube turned white and subtract the necessary time from the necessary test tubes. We did a preliminary experiment and found out that the experiment worked best at 35 C. ...read more.

Conclusion

To get round this problem a Colorimeter could be used. A colorimeter is a device, which calculates the colour intensity of a solution by sending a beam of light through it and seeing how much comes out the other side. However using a colorimeter, will make it difficult if not impossible to use a water bath, so by eliminating one problem; another one is created. Another reason why my results aren't perfect is because a tiny change in the amount of lipase added to the solution could have altered all of my results; as the syringes are not particularly accurate. A chemical balance could be used to weigh the mass of the lipase, but the amounts of Lipase involved are so small, a very accurate balance would have to be used. If I had to repeat the experiment again, I would do a narrower range of bile percentages, maybe go up in 0.05% instead of 0.5%. This would make it easier to identify anomalous results; and draw precise conclusions from the graph. Nevertheless my experiment did give me results that are sufficient to give a reliable conclusion. 'The more bile that is added to the reaction between lipase and fat, the faster the reaction takes place.' By looking at my graph I can see that there is a pattern but I cannot see quantitatively what that pattern does. Extension Investigation on enzymes Charlie Lovell ...read more.

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