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Science Coursework: How does temperature

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Introduction

Science Coursework: How does temperature effect the enzyme catalase? Through carrying out this experiment we hoped to find; how the temperature of a substrate, hydrogen peroxide, effects the reaction with an enzyme, catalase, which is found in the blood cells of the liver. We were to find this by measuring how much oxygen is produced, per minute. Catalase is an enzyme, which can be found in the blood cells of the liver, and is there to prevent the accumulation of hydrogen peroxide, which is a toxic substance found in the liver. An enzyme is a protein molecule that speeds up chemical reactions in all living things. Without enzymes, these reactions would occur too slowly or not at all, and no life would be possible. All living cells make enzymes, but enzymes are not alive. Enzyme molecules function by altering other molecules. Enzymes combine with the altered molecules to form a structure in which chemical reactions take place. The enzyme, which remains unchanged, then separates from the product of the reaction. We were able to carry out this experiment because hydrogen peroxide de-oxidises, when reacting with the enzyme catalase, produces oxygen and water, so the oxygen was measured to show the strength of the reaction with changes in temperature. ...read more.

Middle

Once the amount of substrate molecules added exceeds the number of active sites available then the rate of reaction will no longer increase. This is because the maximum number of reactions are being done at once, so any extra substrate molecules have to wait until some of the active sites become available. Results Oxygen collected (cm3) Temperature 1 2 3 4 Average 10�C 7 6 7 6 6.5 20�C 15 16 16 17 16 30�C 20 20 21 19 20 40�C 24 25 20 24 24 50�C 15 15 14 16 15 From these results I was able to form a line graph, complete with a line of best fit, and labelled peak points, and where the rates of reaction dropped. (See graph on next page) Conclusion When the catalase in the liver, the enzyme, reacted with the hydrogen peroxide, the substrate, the chemicals began to produce a foamy substance around the liver. This is because the chemical reaction was taking place, therefore the catalase had begun to break down the hydrogen peroxide. As the catalase and hydrogen peroxide come in contact with each other the catalase enzyme would attempt to combine with the active site of the substrate, the hydrogen peroxide. ...read more.

Conclusion

This will slightly affect all the results but as we carried out all the three steps in the same way for all the experiments it should not have made any difference to the overall result. Looking on my result graph, my results are reliable to my line of best fit. The results have produced us a straight line of best fit to begin with, which then steadily turns into a curve dropping around the temperature of 40�C. Although I have smoothed the curve out, the results do fit to the prediction graph, and the line does match up approximately to the plotted results on the graph. Luckily we didn't come across any odd average results, so we didn't have the problem of having to draw a graph with a sudden fall or peak in the results. The experiments could be improved in a number of ways. It could be repeated more times to help get rid of any mistakes, which may have accorded. A better overall result would be obtained by repeating the experiment more times. The problem of the delay between pouring in the Hydrogen Peroxide, bunging the test tube and starting the stopwatch could have been limited by getting another person to start the stopwatch when the hydrogen peroxide was poured into the tube. But all in all I think we carried out, and proceeded with the experiments well to the planning. ...read more.

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