NAME ____ DATE; _________________________/ 2012 Lab Instructor's Name; __________________________ Module #5 Lab Worksheet 1. Enumerate the 4 key steps used in the Gram stain procedure and explain the role for each reagent. Recognize the color differences between Gram positive and Gram negative bacteria at different stages of the staining process. Role of stain Color of G(+) bacteria Color of G (-) bacteria a) b) c) d) 2. Contrast the morphology and gram reactivity of Staphylococcus epidermidis and E. coli. 3. Compare and contrast the structure of the cell wall of G (+) and G (-) bacteria.4. What is the reason that Gram (+) bacteria appear dark purple and G (-) bacteria appear pink color at the end of the Gram stain? 5. Which category of bacteria is more susceptible to destruction by the enzyme Lysozyme and the drug penicillin? Why? 6. Of what particular clinical value is a Gram stain to a physician? 7. Are Gram stains useful when performed on bacterial cultures older than 2 days?
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