In gram staining, the alcohol acts on (JFR Plant Science 2018)

✅Explanation: The alcohol step in Gram staining decolorizes Gram-negative bacteria by dissolving their outer membrane and damaging the thin peptidoglycan layer, allowing the crystal violet-iodine complex to leach out.

📌 Other Options Explanations:
-(A) Teichoic acids: Found in the cell wall of Gram-positive bacteria.
-(C) Periplasm: Space between the inner and outer membranes of Gram-negative bacteria.
-(D) Membrane lipids: Present in both Gram-positive and Gram-negative bacteria.

🔑Key Points:
-The scientist H.C. Gram differentiated the bacteria on the basis of staining.

✏Gram Staining of bacteria is performed as below:
-Firstly, the bacteria are stained with Crystal Violet then with KI solution.
-After the staining, bacteria are washed with Acetone or Ethyl alcohol.
-Due to washing, some bacteria lose their stain while others retain them.
-Bacteria that retain stain (violet or purple) are called Gram + and bacteria that decolourise or lose the stain are called Gram – bacteria.
-Gram-negative bacteria are counterstained with Saffranine.
-Gram-positive bacteria have a thick cell wall made up of peptidoglycan. The crystal violet enters the cell and forms a complex with iodine.
-This complex gives a purple stain to the cell wall.
-Too large to pass through this thick wall, this crystal violet-iodine complex is not removed by the alcohol rinse (washing), and the stain remains violet.
-Now, to counter the stain, red-colored safranin dye is applied, but it gets masked by the crystal violet-iodine complex.
-Gram-negative bacteria have a thin cell wall made of peptidoglycan, located between the cell membrane and the outer membrane.
-The crystal violet-iodine complex can easily pass through this thin cell wall and hence it gets removed with the alcohol washing.
-The counterstain safranin stains the cell pink or red.

🛑Additional Information:
-Cytoplasm: It is the jelly-like material present inside the cell, that is the main arena of all cellular activities.
-Cytoplasmic granules: These are small condensed cellular materials that appear as spots. These are also called inclusion bodies. They perform the function of nutrient storage in bacteria.