06B Enzyme (Pressure)

06B Enzyme (Pressure) - Experiment Enzyme Action: Testing...

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Biology with Calculators 6B - 1 Experiment 6B Enzyme Action: Testing Catalase Activity Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the chemical activities of living organisms. They act as catalysts, substances that speed up chemical reactions without being destroyed or altered during the process. Enzymes are extremely efficient and may be used over and over again. One enzyme may catalyze thousands of reactions every second. Both the temperature and the pH at which enzymes function are extremely important. Most organisms have a preferred temperature range in which they survive, and their enzymes most likely function best within that temperature range. If the environment of the enzyme is too acidic or too basic, the enzyme may irreversibly denature , or unravel, until it no longer has the shape necessary for proper functioning. H 2 O 2 is toxic to most living organisms. Many organisms are capable of enzymatically destroying the H 2 O 2 before it can do much damage. H 2 O 2 can be converted to oxygen and water, as follows: 2 H 2 O 2 ← → 2 H 2 O + O 2 Although this reaction occurs spontaneously, enzymes increase the rate considerably. At least two different enzymes are known to catalyze this reaction: catalase, found in animals and protists, and peroxidase , found in plants. A great deal can be learned about enzymes by studying the rates of enzyme-catalyzed reactions. In this experiment, you will measure the rate of enzyme activity under various conditions, such as different enzyme concentrations, pH values, and temperatures. It is possible to measure the pressure of oxygen gas formed as H 2 O 2 is destroyed. If a plot is made, it may appear similar to the graph shown. At the start of the reaction, there is no product, and the pressure is the same as the atmospheric pressure. After a short time, oxygen accumulates at a rather constant rate. The slope of the curve at this initial time is constant and is called the initial rate . As the peroxide is destroyed, less of it is available to react and the O 2 is produced at lower rates. When no more peroxide is left, O 2 is no longer produced. 1. 1 2 3 4 Time Pressure rate
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6B - 2 Biology with Calculators Experiment 6B Figure 1 MATERIALS LabPro or CBL 2 interface enzyme suspension TI Graphing Calculator four 18 X 150 mm test tubes DataMate program ice Vernier Gas Pressure Sensor pH buffers rubber-stopper assembly test tube rack 10-mL graduated cylinder thermometer 250-mL beaker of water three dropper pipettes 3% H 2 O 2 Graphical Analysis (optional) 600-mL beaker PROCEDURE 1. Obtain and wear goggles.
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This note was uploaded on 01/17/2012 for the course BIOL 470 taught by Professor Allannelson during the Spring '00 term at Tarleton.

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06B Enzyme (Pressure) - Experiment Enzyme Action: Testing...

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