Bacterial Cell Essay

1936 Words 8 Pages
The cell wall of a bacterial cell has many functions. Not only does it protect the interior of the cell from changes in its environment but it also helps give the cell shape. In bacterial cells, the cell wall helps prevent cytolysis due to an imbalance of water pressure between the inside and the outside of a cell. The cell wall also contributes to the pathogenicity of a species. As explained by our textbook, “the chemical composition of the cell wall helps to differentiate major types of bacteria” (Tortora, Funke, and Case 84). The two main types of bacteria are gram positive and gram negative. Their cell walls are composed of peptidoglycan. The peptidoglycan is a chain of repeating disaccharide held together by polypeptides. The disaccharide …show more content…
Thus, if someone becomes ill, it is imperative that we know the specific microorganism responsible for said illness. Because of this, several biochemical tests have been generated to help us distinct between different species of closely related bacteria. These tests not only help to identify the pathogen but also allow us to administer the appropriate treatment as well as find the source of an illness. In this series of experiments, we examined several enzymatic activities to help differentiate between closely related bacteria. In order to do so, we used several …show more content…
The first test involved the MacConkey Agar. This agar is both selective and differential. This agar allows only for gram negative bacteria to survive. It contains the pH indicator neutral red and the substrate lactose. It differentiates for microbes that can ferment lactose and those that cannot. If a microbe can ferment lactose it will produce acidic waste which will change the pH of the agar causing a color change to pink. If a microbe cannot ferment lactose, the agar will appear colorless. The next test involved the Eosin methylene blue (EMB) agar. The EMB agar is also selective and differential. It selects for gram negative microbes and thus inhibits the growth of gram positive microorganisms. EMB differentiates between microbes that can ferment lactose and those that cannot. This tests the levels of fermentation according to the amount of acid produced. If no acid production is present, the agar will appear colorless. If there is minimal fermentation, the agar will appear pink with black/purple centers. If there exists an excessive amount of fermentation, a green metallic sheen with black centers will be observed. The triple Sugar Iron Agar (TSI) is used to differentiate between different types of gram negative microbes. This slant is located inside a test tube and is considered an aerobic environment. The butt of the test tube is known as an anaerobic environment. If a microbe can ferment

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