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**Introduction** The chemical hydrogen peroxide (H2O2) spontaneously decomposes into water and oxygen gas:
 * An Exploration of Enzyme Activity**

**2 H2O2** **-->** **2H2O + O2** The reaction happens very slowly, but over a number of years a bottle of peroxide will convert almost entirely into water.

The enzyme **__CATALASE__** dramatically speeds the breakdown of hydrogen peroxide. Catalase exists in the cells of many organisms, including humans, to reduce levels of H2O2 that accumulate as a metabolic byproduct. The rate of the catalyzed breakdown of hydrogen peroxide can be measured by the rate of O2 production.

In this investigation, the speed with which O2 bubbles cause a paper disk to rise indicates the relative SPEED of the reaction. Your source of the enzyme will be yeast (//Saccharomyces cerevisiae//) cells.

**I. The tool for Measuring Reaction Rate** Before starting, you will learn how to measure the rate of the enzyme-catalyzed reaction. * Obtain a disk of filter paper. * Drop disk into beaker with yeast/enzyme solution and let soak for a few minutes, * Meanwhile, fill a small beaker or plastic cup with 2/3 hydrogen peroxide * Use tweezers to move the paper disk from the yeast and into the hydrogen peroxide. The disk will sink to the bottom- **begin timing at the moment the disk touches the bottom!** * The disk will float to the surface as it fills with oxygen bubbles **//produced by the breakdown of H2O2.//** * Stop timing when disk reaches top. Record in chart below * Perform 2 more trials, and record.


 * || 1st Trial  ||  2nd Trial  ||  3rd Trial  ||
 * Time (in seconds ||  ||   ||   ||

Hypothesis: If the paper disk is more soaked with catalase, then it will float to the top of the beaker faster.

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