• 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. Marked by a teacher

    An investigation into the inhibiting effect of tomato juice on the germination of cress ...

    3 star(s)

    The graph also shows that the results between 15% and 20% are not significantly different. This shows that the negative effect of tomato juice on germination only significantly increases up to a certain point (e.g. the inhibitors have already taken up most of the active sites so if you add more they will have less of a impact).

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

    In each test tube, 3cm3 of milk into each test tube. Another 3cm3 of sodium carbonate was added. This made the solution alkaline so we could see the rate of the reaction. Eight drops of phenolphthalein was added to the milk.

  1. An Investigation Into The Digestion Of Milk By Trypsin.

    I then decided to use the pH variable. I added the five-pH solutions into the five test tubes, and then added 5cm� of casein milk into each of the five test tubes. I then added 5cm� of trypsin into each tube.

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

    substrate to ensure that the concentration of the substrate solution remains constant in all experiments i.e. at 1M. 7. Using a 25cm3 measuring cylinder, measure accurately 15cm3 of buffer solution and pour this into the 20cm3 beaker which contains the substrate.

  2. Investigation into the effect of temperature on the digestion of fat by Lipase.

    Repeat steps 1-3 for water baths- 30 , 40 , 50 ,60 . Diagram: Prediction: I believe that the enzymes will work best at a temperature of around 40 this is because when enzymes are exposed to high temperatures it causes the molecules within the enzyme to vibrate to

  1. The Action of Lipase and Bile Salts On Milk

    PREDICTION Room Temperature In a previous experiment it was demonstrated that the enzyme will operate at room temperature. The enzyme took 8 minutes to completely digest the fat. It is therefore predicted that the enzyme will operate at room temperature.

  2. 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.

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