Bacterial Classification and Gram Staining Mechanism Quiz

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What is the primary stain used in Gram staining?

Crystal violet (CV)

How does alcohol act on Gram-negative bacteria during Gram staining?

Alcohol increases the porosity of the cell wall, allowing the stain to wash off easily.

What is the function of Gram's Iodine in Gram staining?

Gram's Iodine kills microbes and increases cells' affinity for the stain.

What is the purpose of the counterstain in Gram staining?

To color Gram-negative bacteria pink and Gram-positive bacteria purple-black. Signup and view all the answers

Why is proper slide preparation crucial for successful Gram staining?

Incorrect heat fixation can affect the number of bacteria present and their adhesion to the slide. Signup and view all the answers

How does alcohol act on Gram-positive bacteria during Gram staining?

Alcohol shrinks the pores of the cell wall, allowing the stain to be retained. Signup and view all the answers

What is the potential consequence of over decolorizing a gram-positive cell during the Gram staining process?

Extensive damage to the cell membrane and cell wall Signup and view all the answers

How does the age of a culture or colony being stained impact the Gram stain results?

As cultures age, especially gram positive cells, they tend to lose their ability to retain the primary stain and may appear gram variable. Signup and view all the answers

Why is it important to use fresh cultures not older than 24 hours for making Gram-stained preparations?

Older cultures may impact staining results by becoming gram variable. Signup and view all the answers

What is the purpose of maintaining a large collection of strains in a microbiological laboratory?

Stock culture collection is maintained for preservation of microbial cultures. Signup and view all the answers

How might safranin-stained cells appear if the Gram staining process is not carried out correctly?

Darker in color and could be mistaken for a light purple gram-positive stained cell. Signup and view all the answers

What is the significance of the timing of the decolorizing step in the Gram staining procedure?

Timing of the decolorizing step is crucial as over decolorizing or decolorizing for too short a time period can impact staining results. Signup and view all the answers

What is the most important differential stain used in bacteriology?

Gram stain Signup and view all the answers

Who is the Gram stain named after?

Dr. Hans Christian Gram Signup and view all the answers

What are the primary stain, mordant, decolorizer, and secondary stain used in the Gram staining procedure?

<ol> <li>Crystal Violet, 2. Gram's Iodine, 3. 95% Ethyl Alcohol, 4. Safranin</li> </ol> Signup and view all the answers

What should be done in Step 5 of the Gram staining procedure?

Do not over-decolorize; add reagent drop by drop until the alcohol runs most clear, showing only a blue tinge. Signup and view all the answers

What is the purpose of examining the slide under oil immersion in the Gram staining procedure?

To get a closer look at the bacterial cells for classification Signup and view all the answers

How is the Gram stain useful in bacteriology?

It is an essential tool for classification and differentiation of microorganisms. Signup and view all the answers