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An Investigation to Show the Effect of Changes in the Concentration of Hydrogen Peroxide Has On Enzyme Action

Extracts from this essay...

Introduction

An Investigation to Show the Effect of Changes in the Concentration of Hydrogen Peroxide Has On Enzyme Action My Aim My aim is to see if the concentration of hydrogen peroxide has any effect on the rate that the enzymes react. I will also measure the amount of oxygen bubbles given off and see if the concentration of the substrate (hydrogen peroxide) has any effect. Catalase (yeast) catalyses the breakdown of hydrogen peroxide into oxygen and water. My Prediction My prediction is that when the concentration of hydrogen peroxide increases, so will the amount of oxygen bubbles given off. This will occur because as the concentration increases there is then more of the hydrogen peroxide for the yeast to react with. Equipment List * Hydrogen Peroxide- 5, 10, 15 & 20% this will enable us to see if the difference in the strength of hydrogen peroxide has any effect on the rate of the reaction. * Pipette- This will allow us to measure out accurately the correct amounts of hydrogen peroxide and water. * Water- The water is to dissolve the yeast so we can get the same surface area of yeast to react with the hydrogen and also to read the amount of oxygen bubbles given off by the measuring tube full of water.

Middle

Key Science Enzymes speed up reactions, they are made of proteins. Enzymes require a lock and key system, this means that each enzyme will react only once with the hydrogen peroxide. When enzymes heat up they travel faster, this will increase the chance of them colliding with each other. However if they heat up too much this will change the shape of the active site, meaning that there will now not be the correct shaped catalase to react with the new shape of the hydrogen peroxide. Each enzyme has its own key and lock system and therefore will only react once. There are variables with this experiment, one of them being the percentage of hydrogen peroxide. This will allow us to see if the different percentages have different effects on the reaction. Another variable is the amount of yeast used, this is important in order to keep a fair test throughout the experiment. If you change the amount of yeast being used this will either reduce or increase the chance of the yeast (catalase) finding the correct substrate (hydrogen peroxide). Also the amount of water that the yeast is dissolved in will affect the experiment as there will be excess water in the experiment so there will be less chance of the yeast reacting.

Conclusion

As the percentage of peroxide increased, so did the size of the error bars, this backs up the idea of the results being harder to read as the reaction was faster and harder to read on the measuring tube. Therefore the error bars are the biggest during the 20% hydrogen peroxide experiment and smallest during the 5% hydrogen peroxide experiment. The graph has reading ranging from the smallest of 5% -6 to the smallest of 20% - 31 this shows just how different the two strengths of hydrogen peroxide affect the yeast. The largest reading for 5% and 20% were just as far apart as the largest reading for 5% was only 10, but the largest reading for 20% was 44. However some of the higher error bars from 15% overlap with the lower error bars from the 20% results, this shows that 15 and 20% had almost the same effect but 20% reacting a little bit more. I conclude that the higher the concentration of hydrogen peroxide the more reactive it is with the yeast. This is because there is more of the substrate for the catalase to react with, the reaction is more furious but it only lasts for the same time before the reaction stopped. My conclusion also backs up my prediction of that the higher concentration of hydrogen peroxide the more oxygen bubbles are given off. This is backed up by my graph of results. By Kyle Nealon 10N

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