General Microbiology - are referred to as "cocci"...

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General Microbiology GENERAL Bacteria are unicellular microorganisms having a variety of characteristics allowing their classification. One major classification scheme is based upon their staining properties using the "Gram stain" procedure. In this procedure, heat-killed bacteria are exposed to the purple dye crystal violet and iodine. This combination forms a dye complex in the bacterial cell wall. Treatment of the stained bacteria with a decolorizer like ethanol will wash away the dye complex from some bacteria but not others. Bacteria that retain the crystal violet-iodine complex appear purple and are called "Gram-positive". Bacteria that lose the dye complex can be counterstained with the red dye saffranin so that they appear red. These bacteria are called "Gram-negative". The basis of the Gram reaction lies within the structure of the cell wall, described below . Bacteria also come in many different shapes. Spherical shapes
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Unformatted text preview: are referred to as "cocci" while elongated cylinders are called "bacilli" or "rods". Some bacteria are slightly elongated cocci and these are referred to as "coccobacilli". Even other bacteria have a corkscrew-like appearance; these spiral forms are often called "spirochetes". Individual cells may also be arranged in pairs or clusters or chains. Thus, may morphologies are possible and these can be useful for the identification of bacterial genera. ( Click here to see a bacterial classification flowchart ). The ability of a bacterium to cause disease is known as its virulence. Factors involved in determining virulence potential are discussed here . In terms of the medical aspects of bacterial structure , we are most interested in those features that interact with the host. These features are found predominantly on the outer surface of the bacterial cell. This page will describe some of these features....
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This note was uploaded on 11/05/2011 for the course BIOLOGY MCB2010 taught by Professor Jessicadigirolamo during the Fall '10 term at Broward College.

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General Microbiology - are referred to as "cocci"...

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