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Unformatted text preview: Taarika George Partner: Casey Watrous Period F Due 10/18/04 Factors Affecting Enzyme Activity INTRODUCTION Enzymes are biological catalysts (usually proteins) that speed up rates of chemical reactions that occur in cells. In this experiment, many factors will be studied that affect the activity of enzymes. The specific enzyme that will be used will be catalase, which is in most cells and found in high concentrations in liver and blood cells. Liver homogenate will be used as a source of catalase. It promotes the decomposition of hydrogen peroxide in this reaction: 2H 2 O 2 2H 2 O + O 2 catalase Hydrogen peroxide comes as a by-product of chemical reactions in cells. It is toxic and would kill cells if not removed immediately or broken down. It is also used as an antiseptic, but it isnt a good antiseptic for open wounds. If catalase-soaked disks are used, then the more disks that are used, the more oxygen because more hydrogen peroxide will be used. If the enzymes are put in different temperatures, then the enzymes in the higher temperatures will produce more oxygen, because chemical reactions occur faster in higher temperatures. If the pH of the solutions increase, then the chemical reactions will occur faster because the enzymes work better in a basic environment than an acidic one. The independent variables in this experiment are temperature, concentration of catalase soaked disks and pH levels. The dependent variable is the amount of 0 2. MATERIALS (per team of 3) 3 pairs of safety goggles 3 lab aprons 50-mL beaker 2 250-mL beakers 10-mL graduated cylinder 50-mL graduated cylinder reaction chamber 6 18-mm X 150 mm test tubes forceps square or rectangular pan test-tube rack nonmercury thermometer filter-paper disks ice water bath at 37 degrees C buffer solutions: pH 5, pH 6, pH 7, pH 8 catalase solution fresh H 2 O 2 (3%) METHOD Part A 1. Prepare two tables similar to the one attached. One will record the teams data and one will record data averaged for the entire class. 2. Obtain a small amount of catalase solution in a 50-mL beaker. 3. Obtain a reaction chamber and a number of filter-paper disks. 4. Place four catalase-soaked filter-paper disks on one interior sidewall of the reaction chamber. (They will stick to the sidewall.) Prepare a disk for the use in the reaction chamber by holding it by its edge with a pair of forceps and dipping it into the catalase solution for a few seconds. Drain excess solution from the disk by holding it against the side of the beaker before you transfer it to the reaction chamber. 5. Stand the reaction chamber upright, and carefully add 10-mL of 3% hydrogen peroxide solution. Do not allow the peroxide to touch the filter-paper disks ....
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- Spring '98