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How temperature affects the rate of an enzyme controlled reaction.

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How temperature affects the rate of an enzyme controlled reaction Aim: To investigate how temperature affects the rate of an enzyme controlled reaction. Variables: There are 4 variables, which can be changed in this reaction: -Concentration -Quantity -P. H. -Temperature I am going to investigate how temperature affects the rate of an enzyme controlled reaction so I am going to change the temperature. The other 2 variables must be kept the same. I will keep the others the same by using the same amount of substances at the same concentration and the same pH. This will help to make the investigation a fair test. Preliminary Work: In my preliminary work I found out that 15cm3 of 2% Starch and 5 cm3 of 0.1% Amylase worked at the best speed. Any more amylase or less starch worked to quickly and anymore Starch and less Amylase took too long. Safety: As this experiment involves enzymes that can be harmful and high temperatures some safety equipment must be used: -Safety Specs. ...read more.


This is because it is the starch in the solution that turns the iodine darker. All the starch needs to go for the iodine to stop changing colour. The enzyme amylase breaks down the starch and turns it into another substance. But for the amylase to react and breakdown the starch it must collide with it and join on to it. They fit together like a lock and key, which means that only the right enzyme can fit and break the substance down. As amylase is the right enzyme to breakdown starch they fit together perfectly. When they lock together amylase breaks the bonds and splits the starch into smaller pieces creating a new substance called maltose. The maltose doesn't change the iodine's colour. When the iodine remains the same colour it means that there is no more starch left in the solution and so the reaction is completely over. The higher the temperature, the faster the enzymes move about. ...read more.


As the temperature increased the reaction took less time. My graph has the predicted shape and shows a positive correlation. However the second part of my prediction was incorrect. After 40?C the reaction did not slow down. This is because it is bacterial amylase we used in the experiment. Bacterial amylase works at a different temperature to the amylase inside the human intestine, which is what I predicted for. This is why the reactions are still increasing in speed, up to 70?C. Too find the temperature at which bacterial amylase actually works fastest I repeated the experiment at 80?C and 90?C. These were my results: Temperature Time taken for starch to be broken-down (seconds) ?C Attempt 1 Attempt 2 Attempt 3 Average 80 90 This shows that bacterial amylase actually works quickest at 70 ?C, as after that temperature the reaction slowed down. By 90?C the enzyme was so denatured that it couldn't break down the starch at all. Evaluation: My results were fairly accurate and the procedure was reasonably reliable. ...read more.

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