Biology

Lab Report 1 Principles of Biology 1(BIOL 100)

Fall 2001 Gerard Chretien

Living cells perform a multitude of chemical reactions very rapidly because of the participation of enzymes. Enzymes are biological catalysts, compounds that speed up a chemical reaction without being used up or altered in the reaction. The material with which the catalysts reacts, called the substrate, is modified during the reaction to form a new product. But because the enzyme itself emerges from the reaction unchanged and ready to bind with another substrate molecule, a small amount of enzyme can alter a relatively enormous amount of substrate.

This report will illustrate the enzymatic action of the enzyme catecholase, which is common in plants. To study this particular enzyme in a laboratory, the natural substrate catechol is oxidized by the removal of two hydrogen atoms. The substrates of the enzyme are catechol and oxygen. These substates react with one another within the active site of the enzyme. The products formed by this reaction are benzoquinone has a brown color, you can see that the reaction has taken place. This is called the fruit browning reaction. Benzoquinone inhibits the growth of microorganisms and prevents damaged fruit from rotting. In undamaged cells catecholase is stored in vesicles and does not interact with catechol.

In the presence of the enzyme catecholase:

Catechol+1/2O2 benzoquinone+H2O

The structure of the enzyme is mainly dependent on the active site and variable groups. Extreme temperatures or extreme pHs can alter the structure of an enzyme. Enzymes function to lower the activation energy to break the bonds. They achieve this by putting stress and pressure on the bonds or creating a microenvironment for the substrate. A change in the temperature or a fluctuation in pH can alter...

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... questions and test answers. The method has five stages:

1. Making observation.

2. Asking questions.

3. Forming hypotheses, or tentative answers to the questions.

4. Making predictions based on the hypotheses.

5. Testing the predictions by making additional observations or conducting experiments.

The information gained may support or yield opposite results based on predictions being tested. My independent variable would be time and the dependent one would be the enzyme pectinase. I believe the key feature of my experimentation is the control of most factors so that the influence of a single factor can be seen clearly.

The setting would take place within a laboratory, equipped with various components such as tubes, microscope and other related equipment. I would try to investigate the physical properties of pectin such as molecular weight, molecular conformation and aggregation of pectin molecules in the solution. In regards to the pulpiness of the applesauce, I would use the pectin as a emulsifier and stabilizer. This procedure would reduce the pulp of the applesauce considerably without making the solution too watery.