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What effect do different concentrations of bile have on the lipase activity?

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Problem: What effect do different concentrations of bile have on the lipase activity? Experimental Design: Lipase is a digestive enzyme commonly used in our digestive system. There are several types of lipase including pancreatic lipase (mostly) and salivary lipase. Bile is a solution containing negatively charged bile salt, which separates the insoluble lipid into smaller pieces and kept them small (emulsification). To test different concentrations on the lipase activity, obviously more than one different concentration of bile solution is used and lipase concentration and volume are controlled. To isolate the effects of different [bile] on lipase activity as a single variable, any other variables effecting lipase activity would be controlled. The source of fat is cream and volume/concentration of sodium bicarbonate must be the same in each individual trial. It is entirely possible that different volumes of phenolphthalein would effect the pink intensity of individual test tubes, thus in caution, the drops of phenolphthalein is also controlled. Variables: Manipulated- the concentration of bile in each test tube Controlled- the temperature in which the lab is performed - The concentration/volume of lipase in each test tube - The number of drops of phenolphthalein in each test tube - The volume of total solution - Volumes of cream and sodium carbonate - Concentration of sodium bicarbonate Responding- the time in which the indicator changes ...read more.


18) Repeat steps 5- 9. 19) Repeat step 3 for the test tube labelled 5. 20) Add 4mL of bile into test tube 5. 21) Repeat steps 5- 9. 22) Repeat all steps (1- 21) in order to have 3 replicates of this lab. Table #1: Time Intervals Recorded for the Change of Color of the Indicator of Different Test Tubes. The time interval for three replicates is recorded. Volume of Bile added to Test tube (mL) Time for pink to dissipate (Replicate one)(min:secs) Time for pink to dissipate (Replicate two) (min:secs) Time for pink to dissipate (Replicate three) (min:secs) 1 14:52 19:16 6:57 2 3:25 12:43 7:55 3 3:00 8:43 6:27 4 3:09 2:31 5:50 5 2:19 4:23 5:13 Analysis/Discussion: First thing to be noticed is that the time interval for replicate #1, test tube #1 seems to be out of place when compared to the rest of replicate #one. In replicate #one and replicate #three, test tube #5s are clearly the least time within their respective replicates. According to the procedure, test tube # 5 has the highest bile concentration and according to the hypothesis, it should have the least time. The observations from test tube # 5, both replicate #1 and #3 confirm that. ...read more.


In order to record the time elapsed during each individual experiment, one person must make an interpretation/judgement on when to stop the time based upon his/her ideas. Because of this interpretation, there could be differences of opinions on the time interval between the partners, resulting in an inaccurate recording of time elapsed. 2. A minor source of error could be changes in the substances/materials exposed to air in respect to elapsing time. For instance, some cream is known to change in physical properties (states) when the ambient temperature increases. Assume that the cream used in the experiment was taken out of the refrigerator at a certain temperature, and trial one was carried out immediately, followed by trial 2 and so on. By the time trial #5 is complete, the cream has endured time (which allowed for slight differences of cream) that is not included in trial #1, producing a different cream used in trial #1. The result is some minor difference between trials. 3. The procedure is judged adequate because it is simply to follow and straight forward. 4. Possible improvements for this lab could be that one test use fresh and another test uses an old cream. The purpose of this set of experiment is to test whether slight differences in creams cause any significant differences in the time elapsed. ...read more.

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