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Yeast cells contain enzymes. I am going to investigate the enzyme catalase.

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YEAST COURSEWORK PLANNING INTRODUCTION Yeast cells contain enzymes. I am going to investigate the enzyme catalase. This is how it works: Hydrogen Peroxide Water + Oxygen H2O2 H2O + O I have trapped the yeast cells in jelly, so that when oxygen gas is formed, they rise to the surface. I will investigate the effect of different temperatures on the enzyme catalase. To do this I will heat the enzyme to different temperatures and see how long it will take the yeast cells to rise to the surface. SAFETY AND FAIRNESS To make sure this will be a safe and fair test I will wear safety goggles and not consume anything in the vicinity of the experiment. To make sure the results are fair I will use the same size yeast balls, use the same thermometer and same equipment. PREDICTION I think that the yeast balls will rise to the top the quickest at about 37�C. When the hydrogen peroxide is at a greater temperature than this the yeast will take the longest time to rise. At a temperature lower than this then the yeast balls will take longer to rise, but not as long as when the hydrogen peroxide is at a greater temperature than 37�C. ...read more.


I know that the more common enzymes work best at around 40�C. Their optimum temperature is actually 37�C. If this temperature begins to rise or drop the reactions slow down, this will continue to happen until the enzyme is denatured. It becomes denatured at around 60�C. This happens because the enzyme becomes misshapen. This means that the enzyme will no longer work because it will no longer fit, the active site will be ruined. The enzymes react like a lock and key, only one lock fits the key. When the two join then you get the chemical reaction. When too much heat gets applied then the lock gets changed and so the key doesn't fit the lock so there is no reaction. EXPERIMENT RESULTS TEMPERATURE, �C TEST, SECONDS TAKEN TO RISE AVERAGE, SECONDS TEST 1 TEST 2 TEST 3 10�C 23 25 22 23.3 20�C 20 20 21 20.3 30�C 17 19 17 17.7 40�C 16 16 17 16.3 50�C 40 44 45 43.0 ANALYSIS WHAT I HAVE FOUND OUT From my results I can see that when the temperature is somewhere between 30�C to 50�C, the yeast cells rise the quickest, and therefore are producing the most amount of oxygen in the shortest space of time. ...read more.


You put the yeast balls in at the same time and just record which yeast balls of which temperature reaches the surface first. Also, rather than using temperatures 10�C apart, I'd use ones a lot closer, and I'd also get a lot more results, so rather then doing temperatures from 10�C to 50�C I'd use temperatures from -10�C to 70�C. The other thing that would need improving in the experiment is the fact that heating the hydrogen peroxide and measuring it will just a bunsen burner and a thermometer is very inaccurate. You'd have to use another method of heating the hydrogen peroxide, and keeping it at a constant temperature, otherwise the hydrogen peroxide will cool down during the experiment. MORE EVIDENCE To really support my theory, I would definitely need more evidence, but the only evidence, which would be worth anything to prove my theory, would have to be in more tests. EXTENDING THE EXPERIMENT If I extended the enquiry further I believe I would probably find that enzymes are very particular about the temperature they work in. I also believe that if the temperature went low are high enough the enzymes would stop working altogether and possible even die. MARK GLENISTER 64870 8095 01/05/07 - 1 - ...read more.

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