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During this investigation my aim is to find out which temperature lipase digests fats into smaller soluble particles best. I will begin by looking at my background information so I can make a justified prediction.

Extracts from this essay...

Introduction

Vikki Kirkpatrick 10BH Biology Coursework - Mr Saunders Investigating Lipase Aim During this investigation my aim is to find out which temperature lipase digests fats into smaller soluble particles best. I will begin by looking at my background information so I can make a justified prediction. ******************************** Background Information I already know that lipase is an enzyme. Enzymes are made inside cells and once formed can leave the cell, in which it was made to exert its action outside. These enzymes are called extra cellular enzymes. Extra cellular enzymes include enzymes known as digestive enzymes; these enzymes work in the body break down food substances in the gut. Lipase is one of these digestive enzymes. Lipase is an enzyme that works in the small intestine it digests fats into smaller soluble particles called glycerol and fatty acids. I also know that Lipase works best in neutral conditions. We are going to use bile in our investigation. Bile is not an enzyme; it emulsifies the fats in the small intestine so the lipase has a greater surface area to work over. We know from a previous experiment from year 10 that the higher the concentration of bile salts we use the more efficiently the lipase will work to break down the fats in the milk.

Middle

2. Using the syringe put 3cm of milk (full ream, 3.6% fat) into each test tube. This is what we call the substrate. 3. Rinse the syringe and then add 5cm of dilute sodium carbonate solution to each test tube. This will make the mixture alkaline. 4. After rinsing the syringe again add 1cm of 3% bile salts to all of the tubes. 5. Next, u must add about 6 drops of phenolphthalein to each test tube (try to give each test tube about the same amount) and shake each one until it has turned completely pink. 6. Fill your 4 beakers with the varying temperatures of water (20?c, 30?, 40?, 50?c and 60?) 7. Put one test tube into each beaker. 8. Then add the lipase (it is very important you start the timer now!) 9. Lastly you must note the time it takes for each test tube to turn from white to pink. 10. NOTE: the syringe must be rinsed after EVERY usage. **************************************** Results This table shows the time taken for each test tube to turn from white to pink at the various temperatures. It also shows the average for each temperature. It shows the averages so I can construct a graph of the averages at a later stage.

Conclusion

If we had used proper water baths in the experiment we could have done more temperatures than we did as this would have given us more points to plot on your graph so it would have been more accurate and also we would have got a more accurate time at which the lipase works best, if I had been able to do this I would have used temperatures such as, 10?c (which was too lower a temperature to be able to keep it constant without a proper water bath), 25?c, 35?c, 45?c and 55?c. Another way we could have bettered our experiment would have been to start our timing from the exact moment that the lipases is added, as this is in fact the moment at which the reaction begins to take place, and therefore the moment at which the timing should begin. Also, to further my investigation I could also consider doing extra experiments in a similar field, using different variables. For example I could vary the PH of the lipase, this would allow me to find the optimum PH for lipase and would tell me whether lipase works best in acidic or alkaline conditions. I could also consider varying the type of milk that I use in my experiment. I would do this because different milks have different amounts of protein and fat in them, this may then affect our results. 1

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