Biology Enzyme Lab

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Enzyme Lab

Introduction/ Abstract

An enzyme is a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction. They are mainly made up of proteins and can tremendously speed up reactions. E. coli ( a bacterium) has about 1,000 different types of enzymes floating around in its cytoplasm at any given time. Enzymes can be used to join and even break up molecules as shown in the diagram below.

(1) A maltose molecule is about to go into an maltase enzyme which are
shaped to fit maltose molecules perfectly.
(2) The molecule enters the enzymes active site and prepares to be broken down.
(3) The maltose molecule's bonds are broken down to produce 2 glucose
molecules which then proceed to leave the enzyme.

We will be investigating an enzyme in this experiment. Catalase to be more specific which is found in the liver. We will compare its action under different conditions with an inorganic catalyst called manganese dioxide.

The purpose of performing this lab is to compare the action of catalase to a non-protein catalyst under different conditions.

In section A, I hypothesize that the sand will have no reaction but the MnO2 will produce a gas or start to foam up. In section B, I suspect that the liver may start to show signs of deformation or shrink in size. The potato will foam up like the liver in section A. In section C, I think there will be no reaction for either substances. Both liver will most likely start to foam up in section D. Finally, in section E, the boiled liver will produce no reaction but the other 2 will most likely have a reaction where bubbles are produced.


* 3% hydrogen peroxide
* Manganese dioxide
* Fresh or frozen liver
* Potato
* Ice
* Fine clean sand
* Stirring rod
* Bunsen burner or hotplate
* 250mL beaker
* test tubes
* scalpel

A. Catalytic reactions
2 ml of hydrogen peroxide was added to two test tubes. 0.1g of sand was placed in one test tube and o.1g of manganese dioxide was added to the second tube. The reaction was then observed and recorded.

B. The effect of an enzyme
2 ml of hydrogen peroxide was added to each of two clean test tubes. A small piece of liver was placed into one of the test tubes and in the other, a small piece of potato. The results were then recorded and compared with the results from the manganese dioxide. We then put the materials to the side.

C. Re-using an enzyme
The liquid portion of the previous tube in B were divided containing the liver into two test tubes. The liver from procedure B was cut into two equal portions and added to two test tubes. Then a fresh piece of liver was added to the first test tube and 1 ml of hydrogen peroxide was added to the second tube. The results were then recorded.

D. Effect of particle size
A small piece of liver was placed in one test tube and a small piece of potato was placed in a second tube. A pinch of sand was added to each test tube and crushed with separate stirring rods. 2 ml of hydrogen peroxide was added to each tube, then the rates of the reactions were observed and recorded. The results were then compared with the results of the uncrushed liver and potato in part b.

E. Effect of temperature
A small piece of liver was placed into a test tube and was heated for 5 minutes in a boiling water bath. 2 ml of hydrogen peroxide was added to the boiled liver and the results were recorded.

A small piece of liver was placed into each of two test tubes. One test tube was placed into a 37oC water bath for 5 minutes and the second tube was placed in an ice-water bath for the same length of time. 2 ml of hydrogen peroxide was added to...