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Unformatted text preview: MICB 201 Chapter #2 Answers Problem #1 Experiment #1 (comparing the effect of lysozyme on Gram +ve and Gram -ve bacteria): Lysozyme kills cells by disrupting preexisting peptidoglycan. In order to have an effect, it must gain access to peptidoglycan which lies outside the cytoplasmic membrane. The PG of Gram +ve bacteria is exposed to the environment while the PG of Gram -ve bacteria is protected by the OM. Thus the Gram +ve bacteria more susceptible to lysozyme than Gram -ve bacteria. Experiment #2 (comparing the effect of lysozyme on a Gram -ve bacterium +/- EDTA): The Gram -ve bacterium can be made susceptible to lysozyme by combining it with EDTA. Why? As the problem states, EDTA binds Ca +2 and Mg +2 ions. Such ions are present in the outer membrane of Gram -ve bacteria where they prevent electrostatic repulsion between LPS molecules which would destabilize the membrane. It is expected that removal of these ions by EDTA would disrupt the outer membrane allowing lysozyme to penetrate to the PG in...
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This note was uploaded on 01/25/2010 for the course MICB MICB201 taught by Professor Kion during the Spring '10 term at The University of British Columbia.
- Spring '10