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I endeavour to primarily investigate the factors that affect the efficiency of lipase and also study in detail how the concentration of lipase affects the speed at which it can breakdown lipids in the body.

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Introduction

09/01/03 GCSE Coursework: Biology James Hare Investigating the factors that affect the efficiency of the enzyme, Lipase Planning Experimental Procedure: Aim: I endeavour to primarily investigate the factors that affect the efficiency of lipase and also study in detail how the concentration of lipase affects the speed at which it can breakdown lipids in the body. Preparatory Research: Enzymes are large globular protein molecules found in plants, animals, humans, and all living things. They are necessary for the building and rebuilding of tissues and cells. Enzymes are catalysts that influence all life systems in our bodies, and are produced by living cells but are capable of acting independently. They are complex proteins that can induce chemical changes in other substances without being changed themselves. Nota Bene: Enzymes can catalyse the forward and reverse reactions equally. An enzyme is a biological catalyst produced in cells, and capable of speeding up the chemical reactions necessary for life. They are highly specific, with each chemical reaction requiring its own particular enzyme. The enzyme's specificity arises from its active site, an area with a shape corresponding to part of the molecule with which it reacts (the substrate). The enzyme and the substrate slot together forming an enzyme-substrate complex that allows the reaction to take place, after which the enzyme falls away unaltered. Logically, this is called the 'lock and key mechanism'. The activity and efficiency of enzymes are influenced by various factors, including temperature and pH (Potential of Hydrogen) ...read more.

Middle

We also discovered that bile salts increase the rate of reaction. In the body, bile salts assist in the breakdown and absorption of fats into the body. Predictions: I predict that the higher the concentration of Lipase, the faster the reaction will occur. I believe this is because there will be more particles of reactant in the solution which makes collision more likely. This is linked to the Collision Theory, which explains how chemical reactions take place and why rates of reaction alter. Method: Equipment needed: Test tube racks Test tubes Thermometers Beakers Source of hot water Electronically controlled water bath or simply a normal water bath 10cm� Syringes 1cm� Syringes Marker pens Stopwatch accurate to a hundredth of a second Pipettes Sodium carbonate solution* Phenolphthalein** Full fat milk (3.6% fat)*** Bile salts Lipase solution Goggles *Sodium carbonate is used to neutralize acids. **Phenolphthalein is an acid-based indicator that is clear below pH8 and red above pH9.6. ***Milk is usually around pH6.8, slightly lower that neutral (pH7). Step-by-Step Procedure: 1. Start by taking any safety precautions that are needed, bearing in mind that you are working in a laboratory with many alkaline and acidic solutions. Id Est: Put on goggles, tie back long hair and store all bags under tables. 2. Assemble a test tube rack with six test tubes in it. Use the marker pens to number the test tubes from 0 through to 5. This will indicate the percentage of Lipase that will be added later. ...read more.

Conclusion

This means that as the lipase concentration is increased, the rate of reaction falls. To improve this experiment, I think it would be useful to have access to data-loggers and other electronically controlled equipment rather than doing things manually. This is because whenever there is human involvement; there are chances for human err. Using an electronically controlled water bath would reduce the margin of error and would maintain a constant temperature to perform the experiment in. Another limitation with this particular experiment is that the volume of liquid in each pipette-drop can vary slightly, so the results may not be truly accurate. I think that the primary limitation with this experiment was the judgement by eye of when the solution had turned colour, as this is not going to be completely accurate and the same for each experiment. I considered conducting the experiment in another way, but as no gas was given off that I could collect, I could not measure this. To extend the enquiry, I would devise more experiments to discover the exact pH that lipase works best at and following on from that, the precise optimum temperature that it works at. In a further experiment I could increase the ratio of lipase to water until I can tell that all the substrate is occupying an enzyme molecule, and the addition of more lipase would have no effect. I could also investigate the affect that lipase has on different types of milk. For example, skimmed milk, semi-skimmed milk and condensed milk, which all have different fat contents. From this you can build up a perfect picture of how lipase behaves in a variety of different situations. ...read more.

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