• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Action of Lipase and Bile Salts On Milk

Extracts from this document...


THE ACTION OF LIPASE AND BILE SALTS ON MILK AIM To investigate the effect of temperature upon the action of lipase. Lipase is an enzyme that digests or breaks down fat into fatty acids and glycerol. FACTORS INVOLVED All factors will be kept constant with the exception of temperature that will be varied. The factors to remain constant include: * Concentration of the lipase enzyme * Concentration of bile salts * Volume of milk in each test tube * Volume of phenol phthalein used * Volume of NaCO3 * Concentration of NaCO3 FAIR TEST A syringe will be used to put the bile salts into each test tube. The same syringe will be used for each test tube. This is to prevent cross-contamination as the syringe will only contain bile salts. Similarly a single syringe will be used to put the enzyme into each test tube. Again this is to prevent cross-contamination as this syringe will only contain the enzyme. Immediately after the enzyme is added the solution will be stirred thoroughly. This is to encourage all of the enzyme to come into contact with the fat and the bile salts. ...read more.


PLAN Two test tubes will be placed in water baths at the following temperatures: 10 degrees; 20 degrees; 30 degrees; 60 degrees and 80 degrees. Two test tubes will be left at room temperature. The average time taken for each of the two tubes at each temperature will then be taken. Each test tube will be left in the water bath for 3 minutes. METHOD In each of the 10 test tubes we added 3 cm3 of milk, 3 cm3 NaCO3, 5 drops of phenolphthalein and 1 cm3 bile salts. 1 cm3 of lipase enzyme was placed in each of the water baths and left to reach the temperature of the water. After the lipase had been in the water baths for 3 minutes it was added to each of the test tubes. The two test tubes being tested at room temperature also had 1 cm3 of lipase added. The time taken for the colour of the solution to change from pink to white was taken using a stop clock. RESULTS The results of the experiment are set out in the following table: Test Tube Temp (?C) ...read more.


The Phenol Phthalein was used because it is an indicator which is pink when alkaline and colourless when acidic. As a result of the presence of the NaCO3 the solution is alkaline at the start of the experiment. The indicator is therefore pink. As the enzyme acts the fat is broken down into fatty acids and glycerol. The solution therefore becomes more acidic and the indicator becomes colourless. The rate of enzyme action can therefore be monitored according to the speed of change in the colour of the indicator. ACCURACY The accuracy of the experiment may have been affected by the following factors: Slight variations in the concentrations and volumes of enzyme, substrate and other substances used in each of the test tubes. This would be caused by inaccurate measurements of the substances. Impurities in the solutions. Temperatures may have fluctuated in test tubes as water baths not kept at a constant temperature. To provide a more accuarate result the number of test tubes used in each temperature control could have been used. The average would then have been more reliable. More temperature controls could have been used (e.g. at 5 degree intervals). Natural lipase from the body could have been used in a separate experiment and the two experiments compared. 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. A2 coursework- The effects of bile salts on digestion of fat

    all work surfaces from bags and coats to prevent accidents occurring * If any glass is broken then clear it up with a dust pan and brush and dispose of it into the broken glass bin * Lipase can cause irritation to the skin * Bile salt if ingested can

  2. An investigation into the effect of lipase concentration on the rate of lipid digestion ...

    Tube 1 contains both lipase and bite salts, and we would expect this to produce the fastest rate of reaction. Tube 2 contains lipase only, which we would expect to react, but not at such a great rate as tube 1.

  1. An experiment to investigate the effect of temperature on the action of the enzyme ...

    This turns purple in an alkaline solution, but colourless in an acidic solution. This will help me time the rate of reaction because I will see how long it takes for the solution to turn colourless (a milky colour in this case)

  2. An experiment to investigate the effect of enzyme concentration on the rate of milk ...

    The sample of lipase must be kept in suitable conditions (example; the same temperature throughout) so as not to cause denaturation of enzymes. Also, the same graduated pipette must be used each time. - Fat content of milk: ==> What is it: Triglycerides can be solid or liquid at room temperature.

  1. 'Investigating how temperature affects the rate action of the amylase enzyme on starch.'

    Aim: 'Investigating how temperature affects the rate action of the amylase enzyme on starch.' Having done my Preliminary experiment, I will be now doing the Official experiment. I have identified the major areas to be improved in the preliminary experiment mainly as the results were declared faulty.

  2. Investigating The Activity Of The Enzyme Lipase On Milk

    The pH level would not be an interesting variable to alter because as lipase works in the duodenum, the optimum pH is 8/9 (alkaline) so the reactions will be a clear and predictable shape on a graph, so I do not feel it is worth investigating.

  1. The Comparison of Lipase Digestion with and without Bile Salts.

    lipases are more effective if emulsifying agents e.g. bile salts, are present because they break up the substrate into smaller droplets. Bile, a viscous, greenish yellow fluid is secreted by the hepatocytes in the liver and is stored and concentrated in the gall bladder.

  2. See if the concentration of the substrate (milk) will effect the rate at which ...

    I thought this because the less fat particles there are, the less work the enzymes have to do. However, this is not the case because the more fat particles there are, the more chance there is of an enzyme bumping into it.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work