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Investigating The Rate Of Enzyme Activity With Varying Enzyme Concentration.

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Introduction

Investigating The Rate Of Enzyme Activity With Varying Enzyme Concentration. Introduction. In this experiment I hope to find out the effects of enzyme concentration on the rate of enzyme activity. I will do this by watching the varying levels of reactivity whilst experimenting with liver (which contains catalase) and hydrogen peroxide that will react to give off oxygen. Enzymes are biological catalysts that work according to the lock and key hypothesis. Enzymes contain an active site where the reaction of the two substrates takes place; the shape of this active site determines how effective the enzyme is. The higher the temperature the more collisions between the enzyme and substrates so the more reactions can take place. If the enzyme becomes too hot it will become denatured and the active site will be mutated and ineffective. Also, pH has an effect on the effectiveness of an enzyme. An enzyme needs to be in the right environment (pH) or it again becomes denatured and useless. Before I carried out the final experiment I did preliminary work in which I tried various ways of measuring the oxygen given off from the reaction. The first problem I came across was the matter of taking liver samples.

Middle

Fig 3. For my first experiment I poured 10mls of the stock solution into the test tube and then lined this up with a ruler. I then added 5mls of the hydrogen peroxide and waited 30 seconds and then measured how far up the tube the froth had reached. This was recorded and the tubes were washed. Fig 4. What factors do you need to control or vary in this experiment? I need to control the amount of hydrogen peroxide in each experiment. This must always be the same, I have chosen to use 5mls every time. The amount of stock solution I use will always be 10mls, this is also a constant. I will vary the concentration of said stock solution, by diluting the original concentration as detailed above. This is an independent variable. I will also measure the amount of oxygen released by the reaction. This is a dependent variable as it is dependant on the concentration of catalase. I also need to maintain a constant temperature for all my experiments so this doesn't affect it. I will use the same size tubes and flasks each time so this has no effect on the reaction.

Conclusion

How could the experiment be made more accurate? By using the equipment I did I made sure that all of the oxygen produced was definitely collected. Unfortunately, by using the equipment like I did, it meant that there was a chance that not all of the hydrogen peroxide would react. This was because when the flask was tipped not all of the hydrogen peroxide definitely came out of the test tube on the inside, I believe this was the cause of any inaccuracies in my results. To remedy this I would think it would be better to take a smaller test tube and attach it to the bottom of the flask, or use a small shelf attached to the side of the flask. This way it would make sure all the hydrogen peroxide mixed with all the stock solution. Fig 8. David Harrison 11A Fig 1. The two enzyme hypotheses. Fig 2. Preparing stock solutions. Fig 3. My final experiment. Fig 4. My preliminary experiment. Fig 5. My results. Fig 6. A catalyst and non-catalyst reaction, the alternate route. Fig 7. A catalyst and non-catalyst reaction, the lowered activation energy. Fig 8. How to make my experiment more accurate. ?? ?? ?? ??

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