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The action of lipase.

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Introduction

The action of lipase AIM: Lipases hydrolize fats into glycerol and fatty acids1, therefor to investigate how different amount (1 cm3, 2 cm3, 4 cm3, 8 cm3, 12 cm3, 20 cm3) of 3% lipase solutions break down the fat in 5 cm3 of milk. RESEARCH QUESTION: how fast can different amount (1 cm3, 2 cm3, 4 cm3, 8 cm3, 12 cm3, 20 cm3) of 3% lipase solutions break down the fat molecules in 5 cm3 of milk? INDEPENDENT VARIABLE: amount of 3% lipase solution (1 cm3, 2 cm3, 4 cm3, 8 cm3, 12 cm3, 20 cm3) DEPENDENT VARIABLE: the speed (measured in minutes) of hydrolizing fat molecules CONTROLLED VARIANLE: concentration of lipase solution, amount of milk, amount and concentration of sodium carbonate solution HYPOTHESES: � lipase hydrolize fats into glycerol and fatty acid1 therefore as the amount of lipase is increased, the fat molecules will be hydrolized faster and faster � boiled lipase will not break down fat molecules, because the enzymes denaturate on high temperature Materials: Equipments: -milk -test tubes -0.05M sodium carbonate solution -test tube rack -phenolphthalein indicator -test tube holder -3% lipase solution -dropping pipette -graduated pipette -Bunsen burner -beaker -watch PROCEDURE: 1. Using a graduated pipette, 5 cm3 of milk is placed in seven test tubes. ...read more.

Middle

DATA PROCESSING AND PRESENTATION: Table 4. The action of lipase - average time taken for the solution to become white Test tube number / - Boiled / - Amount of lipase solution added / cm3 0.5 Average time / min half of the range 1 yes 1 - 2 no 1 40.9 9.0 3 no 2 26.6 8.0 4 no 4 17.0 8.0 5 no 8 8.6 2.0 6 no 12 5.0 0.0 7 no 20 2.6 0.5 �The average is reported with half of the range (instead of standard deviation), because of the small number of replicates. The samll number of replicates did not allow to leave out any of the obtained data. - see conclusion and evaluation to see the possible way of avoiding this problem. �Graph 1. represents the data of Table 4. plotted on a graph. On the x axis the independent variable (amount of lipase) and on the y axis the dependent variable (the time taken for the solution to become white) can be seen. The best-fit line is drawn linear, going through the range boxes. If the x and the y values were of the same distance from the origo, then the best-fit line would be 45o. �Tube 1 - boiled lipase is not plotted on the graph because it was the contol test, to make sure that the colour change does ...read more.

Conclusion

� Testing tube 1 and 2 the conclusion was that the enzyme lipase denaturates on high temperature. To go further, I would suggest an experiment to test at what temperature does enzyme lipase denaturate. For this, lipase on room temperature (about 21 Co) and heated lipase (25, 30, 35, 40 and 45 Co) should be used. The independent variable: temperature of lipase, the dependent variable: time taken for the solution to become white, and the controlled variable: amount of solutions added, including lipase. � I would suggest to use 1 drop of 1 M sodium hydroxide insted of sodium carbonate, because glycerol has three alcohol groups and each of these weakly dissociates to give acid character. The carbonate ions react in acid giving off CO2 and a froming a hydroxide after the hydrolysis of water molecules. These then neutralise the acid, so carbonate ions act like a buffer therefore the acid production cannot be registered as fast as it should be. Therefore 1 drop of 1 M sodium hydroxide should be use, to avoid the buffer effect. � The random error of using graduated pipette cannot be avoided. Measuring the time could have been done with the accuracy of seconds, the reason for not doing so is discussed above in the data collection section. 1 Helena Curtis, N. Sue Barnes Invitation to Biology Worth Publisher: New York, 1994, p 532 1 1 ...read more.

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