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The effect of temperature on amylase enzyme

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Introduction

´╗┐Prediction ? I predict that as temperature increases(IV), the time taken for amylase to hydrolyse starch to maltose will decrease (DV). This will be until an optimum temperature of around 60OC is reached, beyond this temperature I expect the time taken for amylase to hydrolyse starch to maltose will increase as the amylase will have denatured. Experimental design The independent variable is temperature and will be controlled using thermostatic waterbaths set at 30oC, 40oC, 50oC and 60oC room temperature will also be used which is _21oC____ The dependent variable is the time taken (minutes) for the amylase to hydrolyse starch and will be measured by testing a sample for the presence of starch every minute using Iodine in a spotting tray and recording the time at which it has completely disappeared (iodine remains orange/ brown). Controlled variables 1. Volume of starch solution used for each temperature was constant at 5cm3 2. ...read more.

Middle

At 70 OC the reaction slowed slightly to 5.0 mins. Reliability The result for 60OC is very reliable as there is no range bar as all 3 results were 3 minutes. The result for 70 OC was very unreliable as the range bar is large with a range of results of 2 minutes. Accuracy and Improvements 1. There are major problems with accuracy when using this technique. The solutions are only tested every minute, hence the exact time at which starch disappears from a tube cannot be determined. This could be improved by taking a reading every 30 seconds. 1. As small particles of starch produce tiny traces of purple in the midst of yellow / brown iodine, the end-point is very subjective. Different people would regard a trace of starch remaining as being a positive or a negative result. This could be improved by colorimeter to measure the % absorbancy. 1. It is hard to judge where the optimum temperature is as the intervals between the temperatures is too large. ...read more.

Conclusion

and the time taken for the amylase to hydrolyse the starch is the quickest. At temperatures slightly higher than optimum (60oC to 70 oC from these results), the time taken for the amylase to hydrolyse the starch increases. This is because above the optimum temperature the increasing vibration of the enzymes causes the hydrogen bonds to begin to break. This changes the specific shape of the enzyme and the specific shape of the active site. Therefore the substrate is no longer complementary to the active site. Less/ no enzyme substrate complexes form and therefore less/ no products are formed. The enzymes are being to denature. Conclusion ? My prediction that as temperature increases(IV), the time taken for amylase to hydrolyse starch to maltose will decrease (DV). This will be until an optimum temperature of around 60OC is reached, beyond this temperature I expect the time taken for amylase to hydrolyse starch to maltose will increase appears to be correct. The wide spread of results around some of the means indicate that further experiments are needed before a more definite conclusion may be made. ...read more.

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