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In this experiment my aim is to find out at which temperature amylase digests starch the quickest.

Extracts from this essay...

Introduction

Amylase investigation Aim: In this experiment my aim is to find out at which temperature amylase digests starch the quickest. Prediction: Enzymes are proteins which are made by living cells. Digestive enzymes break down larger molecules into smaller molecules. Enzymes are biological catalysts. This means that they speed up the rate of a reaction without being used up themselves. Starch, protein and fats are quite large molecules and so they cannot pass through cell membranes into the blood. Sugars, amino acids and fatty acids/glycerol are much smaller in size and so are able to pass through the cell membranes. Digestive enzymes work to break down these larger molecules into smaller ones. Enzymes are sensitive to both change in pH and temperature. Thousands of different types of enzymes are found in each cell. Enzymes are quite specific in their action. Each enzyme has an active site. Active sites are different shapes in which only one substrate can fit into. This active site breaks down the substrate into the products. After the enzyme has broken down the substrate it can still work on another part of that substrate and it continues to break the substrate into the products: For example, the enzyme amylase breaks down starch molecules (substrate) into maltose and other products (products). Amylase can be found in the salivary glands. Amylase breaks down starch into maltose. If the resultant solution is blue/black when added to iodine solution then starch is still present.

Middle

20. Repeat for each temperature to make sure that the results are accurate. 21. Find an average time for all temperatures. Fair test: In this experiment there are a few factors that I will have to take into account to make it a fair test. First I will have to make sure I use the same amount of starch for each temperature. If one has slightly more starch in it the amylase will have more to digest and the time will be longer. If one has less in it then the amylase will have less starch to digest and the time will be quicker. Also the amount of amylase is a factor. Too much amylase means there will be more to break down the starch and the time will be quicker. Too little means that there will be less to break down the starch and the time will be longer. The amount of time the solutions are left before testing is important as well to keep it a fair test. During those five minutes the temperature has to remain constant to keep it a fair test. If the Bunsen burner is left in too long the temperature may raise too high, therefore there will be more collisions and the rate of reaction will be quicker. The temperature needs to be exact to keep it a fair test. Also I needed to decide when it had completely changed and the starch had all been broken down into sugar.

Conclusion

Also I could have used a colorimeter which is a device used to measure colour change. This would have helped to check when the starch had completely changed into maltose. One of the problems I had was that it was difficult to find an exact colour and you had to use that same exact for all of the temperatures. A colorimeter would have made sure that the starch had completely changed each time. Another thing that would have made the results more accurate would have been to use closer temperatures to the optimum. My optimum was 60?c but this was not that precise as the actual optimum could have been anywhere between 51?c and 69?c. If I had done intervals of every 2?c then I would have had a wider span of results and I may have had a different optimum. Also I could have used a water bath (thermostat) to keep the temperature constant. A Further experiment I could do about enzymes is to do the same experiment with salivary enzymes. I would expect to get an optimum of around 37?c as this is body temperature. Also I could do the effects of pH on amylase do see what conditions it works best in. I would expect amylase to work best in alkaline conditions as saliva is alkaline. Amylase is also found in the small intestines and to make the conditions alkaline, secretions are added. These secretions are found in the pancreas and liver and are called pancreatic secretions and bile salts. Other experiments I could do are to see at what temperatures protein and fats are digested best at.

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