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Investigation into the effect of temperature on the working of the enzyme amylase

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Introduction

Investigation into the effect of temperature on the working of the enzyme amylase Plan and Prediction The aim of this investigation is to find out how temperature affects the rate of reaction of the enzyme amylase, which is found in the salivary glands. Prediction My prediction is correct that at low temperatures the time taken for digestion will be slow as there is insufficient energy to make many molecules collide, at a higher temperature there will be more energy therefore more collisions and the reaction will be faster. The molecules have kinetic energy and as this increases so does their mobility, resulting in more collisions. I know that enzymes have optimum temperatures and the enzyme amylase should be 36.8`C- body temperature, so after about 40`C I think that more and more enzymes will be denatured due to the heat. When enzymes are denatured the active site's shape changes so that the substrates can no longer fit and so less and less reactions are able to occur. I have gathered much scientific knowledge that will help me decide how to plan my investigation. I know that amylase has an optimum working temperature, and this in theory would be body temperature as amylase is produced in the salivary glands and works in the mouth. It helps to digest starch and convert it into a simple sugar maltose. All enzymes are proteins and are therefore denatured by excessive heat. I know that a reaction can be affected by pH, concentration, amount of substrate/enzyme and temperature. Most enzymes work best at a pH of about 7, this is because they are all proteins and so are damaged by very acid or alkaline conditions. Rate of reaction and enzyme concentration are directly proportional; as enzyme concentration increases the rate of reaction gets faster. The effect of substrate concentration is different - when the amount of substrate is small the rate of reaction is low as there are few collisions; this steadily increases as the substrate increases but soon all the active sites on the enzymes are full so the rate of reaction stays the same. ...read more.

Middle

This showed that boiling salivary amylase denatures it, as the starch did not turn black using the boiled amylase. This experiment helped me with my prediction. Obtaining Evidence I have collected my results and managed to complete the experiment in the time allowed. During the experiment I made sure I was taking all the safety precautions I stated in "plan and prediction". Results: Temperature ('C) Time (secs) Colour Digested or not 10 30 Black X 10 60 Black X 10 90 Dark brown X 10 120 Dark brown X 10 150 Dark brown X 10 180 Brown X 10 210 Brown X 10 240 Orange ./ 18 30 Black X 18 60 Dark brown X 18 90 Dark brown X 18 120 Brown X 18 150 Brown X 18 180 Orange ./ 28 10 Black X 28 20 Black X 28 30 Black X 28 40 Dark brown X 28 50 Dark brown X 28 60 Dark brown X 28 70 Dark brown X 28 80 Dark brown X 28 90 Brown X 28 100 Brown X 28 110 Brown X 28 120 Brown X 28 130 Brown X 28 140 Brown/orange X 28 150 Orange ./ 40 10 Black X 40 20 Dark brown X 40 30 Dark brown X 40 40 Dark brown X 40 50 Brown X 40 60 Brown X 40 70 Brown X 40 80 Brown/orange X 40 90 Orange ./ 50 10 Black X 50 20 Dark brown X 50 30 Dark brown X 50 40 Dark brown X 50 50 Dark brown X 50 60 Brown X 50 70 Brown X 50 80 Brown X 50 90 Orange ./ 58 10 Black X 58 20 Dark brown X 58 30 Dark brown X 58 40 Brown X 58 50 Brown X 58 60 Orange ./ 70 10 Black X 70 20 Black X 70 30 Black X 70 40 Dark brown X 70 50 Dark brown X 70 60 Dark brown X 70 70 Dark brown X ...read more.

Conclusion

I think I could also improve the experiment by taking more result from within the range that I have chosen, as this would make the resulting best fit curve more accurate. I think my results could have been improved on by repeating the experiment once more and taking the average from that but from my graph I think that my results are accurate enough to back up my prediction. There are no results that do not fit my prediction suggesting that they are fairly accurate. Extension To extend and improve the work I have completed so far I could use actual human amylase because I think that the amylase we used for the experiment is not likely to have been actual human amylase but bacterial amylase. This would be good to find if the results are similar and show the same trend, if I was doing this experiment I would use the same method as I did for this one and include the improvements. It would be interesting to use amylase at varying time away from the last time the person's it was had eaten to find how this effected the results. For example, maybe just before a meal a person may have more amylase present in their saliva. Also I could find the exact optimum temperature by heating the starch and amylase to, for example 37 and doing the experiment, then 39, then 41, then 42 etc. Then when I found the temperature with the shortest reaction time I could do the experiment for the two temperatures above and below it, and find the optimum temperature from these three. I would then repeat this to make the results more accurate. Temperature (`C) Average time taken to digest the starch (secs) Calculation (1/time) Rate of reaction 10 240 1/240 0.00417 18 170 1/170 0.00588 28 135 1/135 0.00741 40 70 1/70 0.01429 50 80 1/80 0.01250 60 90 1/90 0.01112 68 145 1/145 0.00690 ?? ?? ?? ?? Catherine Lee L5B 1 ...read more.

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