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Unformatted text preview: Biology 280L Professor Erika Gehr October 17, 2007 Antibiotics Purpose An antibiotic is a chemical that kills and inhibits the growth of microbes. They can be produced synthetically and also by other microorganisms. They affect cell wall synthesis, break up nucleic acids and cell membranes, and stop protein synthesis and reproduction in bacterial species. Antibiotics became widely used and popular over fifty years ago, but have steadily declined in their effectiveness (Bren). Bacterial resistance occurs either with overuse or with mutation. Some bacteria have developed resistance to antibiotics naturally, long before the development of commercial antibiotics. They may develop resistance to certain drugs spontaneously through mutation. Mutations are changes that occur in the genetic material of bacteria. These changes allow the bacteria to fight or block off the antibiotic (Bren). It is important to understand how and why antibiotics loose there effective because they are the only defense against pathogenic organisms and need to be studied to find ways of developing new antibiotics that work. The purpose of the antibiotic resistance experiment is to test the resistance and/or susceptibility of organisms to certain antibiotics. Three different bacterial organisms, Escherichia coli , Pseudomonas aeraginosa , and Staphylococcus epidemidis , were tested with six different antibiotics to observe the potency of each antibiotic. It is important to test the three bacteria with the six antibiotics because the bacteria are commonly found inside the human body and on the skin surface and the antibiotics are common prescriptions given to the sick. Understanding the strength of antibiotics is important in altering or developing new types which can be more effective. Methods & Materials...
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