2Tues_Smear and simple stains

2Tues_Smear and simple stains - Lab Exercise 6: The smear...

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Lab Exercise 6: The smear and simple staining OBJECTIVES 1. Prepare bacterial smears for the microscopic visualization of bacteria. 2. Perform a simple staining procedure. 3. Compare the shapes and arrangements of bacterial cells. INTRODUCTION Smears Much of your success in staining microbes will come from preparing a good smear. In doing so, you must keep in mind three key goals. First, you want to adhere the cells to the slide so that they are not washed off in subsequent procedures. Second, in doing so, you do not want to overheat the smear so that the cells shrink and you are left with distortion and artifacts. Third, you need to prepare a thin smear, because the thickness will determine whether or not you can visualize individual cells, their arrangement, or details regarding gram-reaction or internal structure. Simple staining The use of a single stain or dye to color a bacterium is called a simple stain. These types of dyes, called basic dyes , are positively charged, containing cationic chromophores. Because the bacterial cells are slightly negatively charged, there is an attraction between the positive dye and the negative cell. Some common basic dyes used
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This note was uploaded on 12/23/2009 for the course BIO 205 taught by Professor Murphy during the Fall '09 term at Miramar College.

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2Tues_Smear and simple stains - Lab Exercise 6: The smear...

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