Investigating the Rate of the enzyme Catalase in breaking down Hydrogen Peroxide.

Investigating the Rate of the enzyme Catalase in breaking down Hydrogen Peroxide

Planning

In this experiment I will be investing the effect on temperature on the enzyme Catalase when breaking down Hydrogen Peroxide. An enzyme is a biological catalyst, which speeds up a reaction, without itself being used up. It works a bit like a pair of scissors, by cutting up the molecule into smaller, simpler parts.

The enzyme of Catalase is found in every living cell and breaks down Hydrogen Peroxide into water and oxygen. This is very important because Hydrogen Peroxide is very dangerous (it is more commonly known as Bleach). It is an irritant and it is produced in every living cell, and can do serious damage if it is not broken down by Catalase. Because normal living processes produce Hydrogen Peroxide, Catalase needs to be present to break it down quickly, and so Catalase can also be found in every living cell.

Here is a reaction diagram to show the reaction of Hydrogen Peroxide and Catalase:

Hydrogen Peroxide + Catalase Water + Oxygen

This diagram shows that when Hydrogen Peroxide reacts with Catalase it produces Water and Oxygen, which are a lot less dangerous than Hydrogen Peroxide. The water and oxygen could also be used in respiration in animals, and it also means that without Catalase, every living thing would not be able to survive without being internally burned in every cell.

To make this investigation a fair test, (by which I mean an experiment where only one variable is changed, and the other(s) stay the same), I will only change the temperature of the Hydrogen Peroxide. I will keep the amount of Catalase constant, and will measure the amount of oxygen produced.

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From a Science Textbook, I found a procedure using a good source of Catalase (a piece of liver) and putting 20ml of Hydrogen Peroxide in a test tube. They left the potato in the Hydrogen Peroxide for 2 minutes and measured the amount of froth left at the end. After trying out this procedure, I noticed a few problems with it. The first was that the amount of foam was not sufficient enough to measure with a standard ruler, because the height of the froth was so low. Another thing was that 2 minutes would not be enough to get a good amount of oxygen from the reaction.

So I then modified the experiment to use a potato as the source of Catalase (because it’s easier to cut and measure). I also changed it to keep the potato in the 20ml of Hydrogen Peroxide for 3 minutes, to give more time to let the reaction take place. But the major change I made, was that instead of measuring how much foam is produced, I will measure how much oxygen is produced, by using an inverted measuring cylinder to measure, in cm3, so to see how much oxygen each reading gives off, and hence, how much of a reaction there is.

Below is a diagram is what I plan the experiment to look like:

My prediction is that the Catalase will work the best when the Hydrogen Peroxide is at a temperature of 36-37ºC. I think this because, as I have mentioned earlier, the enzyme of Catalase is present in every living cell, which includes those of animals, and if the enzyme is present in a human then it will be best suited to this temperature. If the enzyme is too cold or too hot, then the enzyme can become denatured and not work properly, which could ultimately lead in the living thing dying. The closer the Hydrogen Peroxide is to 36-37ºC, the better the enzyme will work and the more oxygen is produced. If it is too cold, then it will not work as well, and also if it is too hot.

Obtaining

Analysis

I can see from my graphs that the 1st, 3rd and average follow the pattern that the closer the Hydrogen Peroxide is to 37ºC, the more oxygen is released during the reaction, because the reaction takes place quicker, and more oxygen can be released during the 3 minutes that the reaction took place.

From the graphs I can see that the 2nd reading did not follow the pattern as closely, which I will mention in the evaluation. This is not because my prediction was incorrect, but was because of problems in that experiment.

The conclusion is that the nearer the enzymes’ environment is to 37ºC, then the better it will work. My average graph and the 1st and 3rd graph show this pattern, and it is quite distinguishable to see.

Evaluation

Overall, I thought that my experiment went quite well. I thought that it was done to the best that I could, but there could be things that could be changed. When measuring the amount of oxygen, the measuring cylinder was not very precise, since you have to look at it straight on for the reading to be accurate; or else you could have made the measurement out by up to half a cm3. This is the same with the thermometer, when measuring the temperature of the Hydrogen Peroxide, because at temperatures of 60ºC, you don’t want to be getting your head to close to read the temperature, because you might burn yourself whilst taking the temperature. As well as measuring this, I also had trouble measuring the Hydrogen Peroxide, because with a measuring cylinder that measures up to 20ml, the spacing was every half-ml, so it made it extremely hard to exactly measure out 20ml.

The graph of the 2nd readings shows that almost all the points were anomalous. This is because when I did this set of results, the tube that I had had a kink in it and this did not allow all the oxygen to pass through the tube (which is particularly noticeable at 30ºC). This means that only a tiny bit of oxygen could get through to the measuring cylinder, and this result is completely worthless.

Other things which could have skewed the results is the length of the potato was quite hard to accurately measure, so there could have been less or more amounts of Catalase, as there was less/more potato. And, even touching the potato can kill cells, which can drastically lessen the amount of Catalase. Also, the temperature for taking the Hydrogen Peroxide off the heat to the time it takes to start the experiment may decrease, which can result in a large change in the reaction.

If I was re-doing this experiment, I would probably use the same procedure as I did in this one, but I would like to be able to use more accurate measuring equipment, so to make the results more accurate, and hence, would mean more.

On the whole, I thought that this experiment went well. The only thing that went really wrong was the second results, which only wrong because of no fault of my self, and it was the equipment that was wrong. I’d like to do this investigation again, because I could see whether my procedure was correct or not, and to see if my prediction, without any anomalous results skewing my averages.