catalase enzyme

Security. Despite the risks in the following experiments are insignificant, you should consult the latest edition of "Safety in the Laboratory School" published by The Association for Science Education (ase.org.uk) before starting the experiment.

Outline. Catalase is an enzyme that occurs in cells of many living organisms. Some reactions release energy in the cell production of hydrogen peroxide as a final product. This compound, which is toxic to the cell, is divided by water and oxygen by the action of catalase. 2H2O2 + O2 = 2H2O

Samples of liver and yeast had fallen into hydrogen peroxide. Oxygen is evolved and the student is asked to extend the experiment to try to determine if an enzyme in the tissues is responsible. Experiments and questions about one hour.

Prior knowledge. The presence of inorganic catalysts, enzymes denatured in boiling; oxygen relights a brilliant brace.

Preparation and materials - by the group

20 volumes of oxygenated water to 50 cm3

cue

liver, about 1 cubic centimeter

20 cm3 of distilled water

1 g of dry yeast

clean sand to about 1 g

granular activated carbon, about 1 g

Team - Group

test tube rack and 4 test tubes

pliers or in attempts to boost the liver in the tube

4 labels or marker spirit

filter funnel

Bunsen burner

filter paper

test tube holder

mortar and pestle

Experiment

The results of the survey is a critical examination of the tissues of plants and animals to see if
containing catalase.

(a) Label three test tubes 1-3.

(b) Pour about 20 mm (depth) of hydrogen peroxide in each tube.

(c) Cut the liver into 3 pieces.

(d) 1 tube add a small piece of liver, the tube 2 and add a pinch of dried yeast.

(e) Insert a brilliant brace in tubes 1 and 2, which is near the liquid surface or on top of the foam.

1 Describe what happens and see the effect in the brilliant brace.

2 How to interpret these comments?

3 There is evidence from this experiment to date, indicating whether the hydrogen peroxide gas or solid?

4 There is no evidence at this stage, which is an enzyme involved in the production of gas in this reaction?

(f) In the 3rd place the tube a few granules of coal and watch the reaction.

5 coal could be an enzyme? Explain your answer.

Assuming 6 (i) the gas (f) is the same as before, and (ii) the coal is almost pure carbon, the result with coal to help you decide on the source of gas in this and previous experiments?

(g) Suppose that the hypothesis is advanced that there is an enzyme in the liver and yeast, which decomposes hydrogen peroxide and oxygen to water, design and carry out an experiment to test this hypothesis.

7 record (s) of the test, (ii) the reasons for doing so, (iii) the observed
results and (iv) conclusions.

(h) Wash the test tube. Designing and implementing an experiment to see if the suspected enzyme in plants and animals can be eliminated and still maintain their properties. The experiment must include a check.

8 Briefly describe the procedure, results and conclusions.

9 Assuming that the liver and yeast each contain an enzyme that splits hydrogen peroxide, there is no evidence to show that the same enzyme? What should I do to find this for some?

Discussion - answers

Effervesce 1 should be observed in all cases, but is stronger with the yeast with the liver. The guardian must Relight incandescent.

2 The oxygen is produced.

3 There is no evidence to indicate whether it is solid or liquid gas. If students think that a company is unlikely to emit a gas that can be remembered in marble and hydrochloric acid, which is the production of solid carbon dioxide. Seems less likely, however, that the yeast and the liver was given oxygen during the treatment with hydrogen peroxide, hydrogen peroxide, which should give oxygen when treated with different substances.

4 So far, no evidence of an enzyme that is involved.

5 A gas out, but not quickly enough to a signal light Relight. Carbone could not
by an enzyme, because (a) is an element and (b) was produced by very high temperatures to destroy enzymes.

6 coal, as an element, which could not be oxygen. The gas must be from
hydrogen peroxide.

7 (i) The experiment must involve tissue boiling and then put them into hydrogen peroxide.
(ii) If it is an enzyme,
(iii) there is no gas.

8 Students should grind the sample with a po 'of sand and distilled water, filter and test the filtrate with hydrogen peroxide. The oxygen is carried out with a force proportional to the witness the original, when the substances have been tested.

The student should boil half of each extract and demonstrate that loses its activity.

9 Apparently, not the fundamental reason why yeast and liver should not have different enzymes that catalyze the decomposition of hydrogen peroxide. To be sure on this point, the enzymes should be extracted and its chemical composition determined.