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

An investigation into the effect of lipase concentration on the rate of lipid digestion in milk, in the presence and absence of bile salts.

Extracts from this document...

Introduction

An investigation into the effect of lipase concentration on the rate of lipid digestion in milk, in the presence and absence of bile salts. Background knowledge Lipase is an enzyme which catalyses the hydrolysis of triglycerides (lipids) into fatty acids and glycerol. In humans, lipid digestion begins in the stomach with lipase in the gastric juice, but mostly occurs in the duodenum and ileum upon the addition of pancreatic juice (containing more lipase) and bile (containing bile salts). Lipid digestion is illustrated in this investigation by the fact that when the lipids in milk are digested, fatty acids begin to accumulate, and the pH of the solution is lowered due to this build-up (this may be observed by the use of an indicator or pH meter). To expand on the point earlier that bile is released into the duodenum, it should be explained that the bile salts which it contains do not hydrolyse lipids as lipase does, but emulsify fat droplets into tiny globules, providing a greater surface area for lipase action; they aid lipase, as opposed to replicating its function. Bile salts are derivatives of cholesterol, and consist mostly of sodium glycochlolate, and sodium taurocholate. ...read more.

Middle

Bile salts are released into the duodenum, where they emulsify fats to aid lipase action. Test tubes 6 These will act as the reaction vessel. Test tube rack 3 To hold test tubes when not in the water bath. Thermostatically controlled water bath at 30�C 1 To ensure a constant temperature. Temperature is known to affect rate of reaction and is therefore a potential variable in this investigation which must be controlled. Distilled water 36cm3 This will be added to the set of tubes not containing bile salts, to ensure a constant volume in all test tubes. pH meter 1 A pH meter will give an accurate digital reading of the pH of a solution at any given point. As fatty acids accumulate through lipid digestion, they lower the pH of the solution. By stating an end pH for the reaction, we can accurately see when this has been reached, removing the subjectivity associated with determining an end point by means of using an indicator (e.g., phenolphthalein). Graduated pipettes 5 5 cm3 To accurately measure out volumes of the reactants; bile salts, milk, lipase and water, and to avoid cross contamination. As the volumes of bile salts, milk and lipase and considered variables in this reaction, it is important to keep their volumes as accurate as possible to produce the most reliable results. ...read more.

Conclusion

The experiment will now be undertaken in the absence of bile salts, to observe the different in rate of reaction which they allow. 1. Set up 6 test tubes, each containing 2cm3 of distilled water, and 5 cm3 of milk. 2. Repeat the procedure exactly as with that in the presence of bile salts, including allowing the test tubes and the pH meter to equilibrate, adding the lipase solutions one by one and recording the time taken for the solutions to reach pH 4, and repeating the procedure 3 times over. 3. Record the results in a table as previously, making sure to state that the experiment was carried out in the absence of bile salts. Risk assessment The risks in this procedure are minimal. * At 30�C, the water bath does not pose any threat for scalding or burns. * Bile salts may only be harmful in ingested in large quantities, and may irritate the eyes. * The lipase solution may irritate the skin, but given the low concentrations being used, it is unlikely to case any damage. Wash the skin is contact should occur, and wear plastic gloves. Sources 1 Cambridge Advanced Sciences: Biology 1, pages 42 - 44. 2 http://www.rsc.org/education/teachers/learnnet/cfb/images/07C.jpg 3 Cambridge Advanced Sciences: Mammalian physiology and behaviour, pages 7 - 8. 4http://www.ilri.org/InfoServ/Webpub/Fulldocs/ILCA_Manual4/Milkchemistry.htm ...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. An Investigation Into The Digestion Of Milk By Trypsin.

    40?C and 60?C Stopwatch Method Once I had received all the apparatus mentioned above, I poured 5cm� of milk into 2 test tubes. I then drew a black 'X' on a piece of paper, which would show me when the solution became translucent as there being a dark background to

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

    I would keep timing until 360 seconds as that was sufficient time for the lipase to break down the fats in the milk. Method The water bath was set up as the diagram below. It was set up as 40�C using warm water from the tap.

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

    ==> How it affects the reaction: Bile concentration can greatly affect the reaction. It is not only altered when more or less bile is added but when more or less milk fat is added. The affect of increased concentration should results in a quicker rate of reaction.

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

    calibrate the pH probe, put it into buffer solution of pH7 5. Add 2ml of lipase to each of the 3 test tubes 6. Add 2ml of bile salt to each of the 3 test tubes 7. Place one of the 3 test tubes into the water bath set at 40�C 8.

  1. Investigation of the effect of adding different concentrations of NaCl to an enzyme-substrate (amylase-starch) ...

    Fungal amylase and glucoamylase can be used together to convert starch to simple sugars. The practical applications of this type of enzyme mixture include the production of corn syrup and the conversion of cereal mashes to sugars in brewing. Hypothesis The above shows the role of the enzyme amylase and the substrate starch in the following experiment.

  2. WHAT EFFECT DOES SUBSTRATE HAVE ON THE RATE OF RESPIRATION IN SACCHAROMYCES CEREVISIAE?

    Substrate concentration is not the variable I am testing. If different concentrations were used, it would affect the volume of CO2 produced by the substrate Length of time By using a stop clock to time the regular intervals, at which I have to take readings of the volume of CO2 produced, for each substrate.

  1. Catalyse Investigation

    I would repeat the experiment more times as this would give me a more accurate average and I would also uses more different values in order to get a more detailed outlook on how enzyme concentration affects the rate of catalyse activity.

  2. Amylase Investigation

    Glucose is then absorbed into the blood. Enzymes in the human alimentary canal and what they digest are shown in Table 1: Table 1 The name enzyme was suggested in 1867 by the German physiologist Wilhelm K�hne (1837-1900); it is derived from the Greek phrase en zym�, meaning "in leaven". Identified enzymes now number more than 700.

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