Question

Arrange the steps involved in Gram-stain procedure:
(A) Staining with Crystal Violet
(B) Staining with Gram’s Iodine
(C) Decolorization
(D) Staining with Safranine
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D)
• B. (A), (B), (D), (C)
• C. (B), (A), (D), (C)
• D. (C), (B), (D), (A)

Hint:

Understand the sequence of steps and their purpose in the Gram-staining process to differentiate between Gram-positive and Gram-negative bacteria.

Answer 1

The Correct Option is A

The Gram-stain procedure involves:
1. Staining with Crystal Violet: This is the primary stain that binds to the peptidoglycan in bacterial cell walls.
2. Staining with Gram’s Iodine: The iodine acts as a mordant, forming a complex with Crystal Violet, increasing the dye’s binding strength.
3. Decolorization: Alcohol or acetone is used to remove the stain from Gram-negative bacteria due to their thinner peptidoglycan layer.
4. Staining with Safranine: The counterstain provides color to Gram-negative bacteria, making them appear pink under a microscope, while Gram-positive bacteria remain purple.