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CCEA How Temperature affects amylase

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Planning The Problem In this course work I intend to investigate the how temperature affects the activity of amylase on starch. Scientific Knowledge Enzymes are biological catalysts; i.e. they alter the rate of a biological reaction. For example the enzyme catalase breaks down hydrogen peroxide to form water and oxygen. There are many enzymes in our body, and each enzyme is tasked with breaking down one substance. The reason why an enzyme can only break down one substance is due to its active site. Every enzyme has an active site, and this active site is specially made to only fit the substance it's designed to break down, so for example its impossible for the enzyme amylase to break down glucose, the only substance that will fit it is starch. In the diagram below you can see that the enzymes active site and the substrate have a matching shape, which is unique and no other substrate can be broken down by this enzyme. This is sometimes referred to as lock and key; where the substrate is the key and the enzyme is the lock and only one key can fit the lock. The enzyme amylase is present in saliva and breaks down starch into maltose. Like other enzymes it is denatured at 60oC. Enzymes are denatured when heat effects their active site which cause them to become misshapen so that in the substrate can no longer fit into its active site rendering the enzyme useless. ...read more.


11. I then shall mix the starch from one test tube with the amylase of another (both taken from the water bath I just recorded the temperature from). At the same time I will start the stop clock. Every thirty seconds I shall take a small sample from the test tube and add two drops of this to a dimple. I shall repeat until when I add the sample the iodine stays orange. I will then record the time it took for this to happen off the stop clock. 12. I will reset the stop clock and repeat step 11. twice for the other two test tubes in the 25oC beaker still recording the time taken. 13. I will then repeat steps 9. - 11. with the for the water baths of temperatures 30 oC, 35 oC, 40 oC and 45 oC. Safety Precautions Make sure there are no obstructions on the floor, i.e. school bags Make sure my tie is out of the way Make sure the apparatus is far enough away from the end of the bench Handle all chemicals carefully Wear safety goggles Strategy for dealing with results 1. Firstly I shall calculate the average time it took the amylase to break down the starch for each temperature. I will use the following equation: I shall record these times in a table 2. I intend to calculate the rate of reaction for amylase to break down starch for each temperature. ...read more.


I also wouldn't change the stop clock as it did what we required of it. e) Evaluation of method. There are several things I would change in my method if I were doing the experiment again. A problem my group had was judging when the iodine was blue-black and when we should sop the clock. Possibly I would use a colour chart if I was to have to do this experiment again or if I could I would use a colorimeter which would make my results far more accurate. Also I think that the time in-between sample was too long, and that a time in-between samples of 10 seconds would make my results more accurate. Also I feel the number of samples we took was slightly too small and maybe if we took sample for every 5 oC from 20 oC to 60 oC. Also if we took several extra samples between 35 oC and 45 oC we may get a more accurate result for optimum temperature. f) To conclude this experiment, I set out to investigate how temperature affects the reaction between iodine and starch. After completing the experiment, I concluded that as temperature increases, the rate of reaction also increases, until 43 oC which is the optimum temperature, and when the rate of reaction is largest. The rate of reaction decreases quite rapidly as the temperature increases past 43 oC until the reaction stops at 60 oC as the amylase is denatured, and cannot break down any starch. ...read more.

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