Gram Stain Analysis Questions Students are expected to answer the following questions in the analysis section once they have completed the gram stain videos: 1. Predict the effect on Gram-positive and Gram-negative cells of the following mistakes made when performing a gram stain. Consider each mistake independently: a. Failure to add the iodine. b. Failure to apply the decolorizer. c. Failure to apply the safranin. d. Reversal of crystal violet and safranin stains. 2. Both crystal violet and safranin are basic stains and may be used to do simple stains on Gram-positive and Gram-negative cells. In light of this, explain how they end up staining Gram-positive and Gram-negative cells differently in the Gram Stain. 3. What is the mordant for the gram stain? What does the mordant do in a gram stain?
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Failure to add the iodine: - Gram-positive cells: The crystal violet will not form a complex with iodine, so the cells will be decolorized and appear pink after safranin staining. - Gram-negative cells: The same effect as for Gram-positive cells, they will appear Show more…
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Answer the following questions regarding the Gram stain. 1. Which group of bacteria has a thicker peptidoglycan cell wall, Gram-positive or Gram-negative? 2. What is the primary stain? 5. What is the secondary stain? 7. What color are Gram-positive cells following the mordant step? Gram-negative cells? 8. What color are Gram-positive cells following the decolorizing step? Gram-negative cells? 9. What color are Gram-positive cells following the secondary stain step? Gram-negative cells? 10. During the Gram stain procedure, what are some procedural errors that could cause: Gram-positive organisms to falsely appear the be Gram-negative? Gram-negative organisms to falsely appear the be Gram-positive?
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The Gram stain differentiates between bacteria based on the composition of their cell walls. What color do Gram-positive and Gram-negative bacteria take, respectively? Which of these factors will affect your Gram stain results? (Given that everything else is done correctly.) Which of the following reagents are parts of the acid-fast stain procedure? What color do acid-fast positive and acid-fast negative bacteria take, respectively? _____________ is a survival structure formed within the bacterial cell wall that allows the cell to survive until environmental conditions improve. What is the primary stain in the endospore stain? [A]. What cellular structure does it stain? [B]. Which dye is the counterstain? [C]. What is the decolorizer used in the endospore stain? [D]. The endospore stain is an example of [A] (simple or differential) stain. What color do endospores take after the endospore stain procedure? [A]. What color do vegetative cells take after the endospore stain procedure? [B]. One example of a differential stain is [A], and a simple stain is [B].
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