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Action of the enzyme catalase.

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Introduction

Action of the enzyme catalase Aims: This is an experiment to examine the enzyme catalase, which living organisms contain this enzyme, how it acts on the substrate hydrogen peroxide, and how its activity changes in different pH conditions. Hypothesis: Enzymes such as catalase are protein molecules which are found in living cells. They are used to speed up specific reactions in the cells. Each enzyme just performs one particular reaction. Catalase is an enzyme found in food such as potato and liver. It is used for removing hydrogen peroxide from the cells. Hydrogen peroxide is the poisonous by-product of metabolism. Catalase speeds up the decomposition of hydrogen peroxide into water and oxygen as shown in the equations below. 2 H2O2 � 2 H2O + O2 It is able to speed up the decomposition of hydrogen peroxide because the shape of its active site matches the shape of the hydrogen peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called an anabolic reaction. ...read more.

Middle

the wooden splint caught fire 6. yellowish solution formed, no foam 7. lots of bubbles were formed, yellowish solution 8. yellowish solution formed with foam on the top Conclusion and evaluation: 1. Sand is the negative control because it does not contain the enzyme catalase. If any other materials act as the sand did (not producing bubbles, foam on the top of the solution), those materials do not contain catalase. 2. MnO2 does not contain the enzyme catalase because it is an inorganic compound. 3. Liver contains the enzyme catalase. Foam appeared as hydrogen peroxide was broken down to water and oxygen. 4. The temperature of H2O2 increased after the addition of liver because the breaking down of H2O2 is an exergonic reaction, that means that heat is produced during the reaction. 5. The H2O2 was broken down to H2O and O2, the glowing wooden splint caught fire due to the presence of the oxygen. ...read more.

Conclusion

When this saturation point is reached, then addision of extra substrate will make no difference. The rate steadily increases when more substrate is added because more of the active sites of the enzyme are being used which results in more reactions so the required amount of oxygen is made more quickly. Once the amount of substrate molecules added exceeds the number of active sites available then the rate of reaction will no longer go up, it will level off. 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. The enzyme activity exposed to different pH was compared only within the acidic and within the basic pH, however all the pH should have been compared. Fig. 2. Shows the effect of pH on enzyme activity. The optimum rate is between pH 3 and 12. Sources: http://medic.med.uth.tmc.edu/path/catalase.htm http://crystal.uah.edu/~carter/enzyme/catalase.htm http://neiljohan.com/projects/biology/enzymes.htm 1 1 ...read more.

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