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Questions and Answers
Which stain is used for bacteria with high lipid content in their cell wall and cannot be stained using the Gram stain?
What color will acid-fast organisms appear as when using the Ziehl-Neelsen stain method?
Which bacteria are exceptions to the general rule that 'all cocci are gram-positive'?
Which bacteria are exceptions to the general rule that 'all bacilli are gram-negative'?
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What is the function of acetone or 95% alcohol in the Gram stain process?
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Which stain is used specifically for staining spores?
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In the Kinyoun stain method for acid-fast staining, what color do acid-fast organisms appear as?
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Which type of media is best suited for the culture of microaerophilic bacteria?
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Which type of media is designed for primary isolation of a broad spectrum of organisms?
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Which hemolysis type on blood agar results in no lysis and no change in the medium?
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Which type of solid media is used for the isolation of bacteria and fungi?
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Which type of media contains chemically-defined substances with a known precise composition?
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Which staining technique is a quick and easy way to visualize cell shape, size, and arrangement of bacteria?
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In which staining technique are basic dyes like safranin, methylene blue, or crystal violet used?
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Which staining technique distinguishes gram-positive bacteria from gram-negative bacteria?
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What is the primary purpose of staining in microscopy?
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Which staining technique uses a physical probe to scan back and forth over the surface of a sample?
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What is the main feature of a differential stain like the Gram stain?
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Study Notes
Staining Techniques
- The Ziehl-Neelsen stain method is used for bacteria with high lipid content in their cell wall and cannot be stained using the Gram stain.
- Acid-fast organisms appear as red when using the Ziehl-Neelsen stain method.
- The Kinyoun stain method is another acid-fast staining technique, where acid-fast organisms appear as red.
Exceptions to Gram Staining Rules
- Neisseria and Moraxella are exceptions to the general rule that 'all cocci are gram-positive'.
- Bacillus and Clostridium are exceptions to the general rule that 'all bacilli are gram-negative'.
Gram Stain Process
- Acetone or 95% alcohol is used to decolorize the bacterial cells in the Gram stain process.
Spore Staining
- The Schaeffer-Fulton method is used specifically for staining spores.
Media for Microbial Culture
- Microaerophilic bacteria grow best in anaerobic media with low oxygen levels.
- Nutrient agar media is designed for primary isolation of a broad spectrum of organisms.
- Sabouraud dextrose agar is a type of solid media used for the isolation of bacteria and fungi.
- Chemically defined media contains substances with a known precise composition.
Hemolysis on Blood Agar
- Gamma hemolysis on blood agar results in no lysis and no change in the medium.
Staining Techniques
- Negative staining is a quick and easy way to visualize cell shape, size, and arrangement of bacteria.
- Basic dyes like safranin, methylene blue, or crystal violet are used in Simple staining techniques.
- Differential staining techniques, like the Gram stain, distinguish gram-positive bacteria from gram-negative bacteria.
- The primary purpose of staining in microscopy is to increase the contrast between the microorganism and its background.
Advanced Staining Techniques
- Atomic force microscopy (AFM) uses a physical probe to scan back and forth over the surface of a sample.
- The main feature of a differential stain like the Gram stain is its ability to differentiate between different types of microorganisms based on their cell wall composition.
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Description
Test your knowledge about the rules and results of gram staining for bacteria. Learn which bacteria stain as gram-positive or gram-negative based on their morphology. Identify the role of different reagents in the gram staining process.
