Gram Staining

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Gram Staining: Gram positive and Gram negative bacteria
One of the most important cytological features of bacteria is their reaction to a simple procedure called, after its discoverer, the Gram stain. The cell wall of bacteria shows a characteristic reaction to the gram stain devised by C. Gram.
Gram Staining Procedure

Gram staining procedure
Source: deenahere
How Gram Stain works? Gram Staining Principle: Step by step procedure with explanation * Gram Staining Principle: Step by step procedure with explanation
Reagent Preparation / Step by step procedure& Principle.
The gram staining procedure involves staining cells with the dye crystal violet and all the bacteria will be stained blue. The bacteria are then treated with an iodine solution and decolourized with alcohol. Those bacteria which retain stain are known as Gram positive and those which do not retain the stain are termed as Gram negative. This is the fundamental difference between gram positive and gram negative bacteria.

Gram positive

Gram negative
Difference between Gram Positive and Gram Negative Bacterial Cell wall:

Bacterial Cell wall

Character | Gram positive | Gram negative | Number of layers | One | Two | Thickness | Thick(20-80nm) | Thin (8-10 nm) | Outer membrane | Absent | Present | Periplasmic space | Present in some | Present in all | Chemical composition | Petidoglycan, Teichoic acid and lipotechoic acid | Lipopolysaccharide, lipoporteins and peptodoglycan | Peptidoglycan | More | Less | Porins proteins | Absent | Present | Lipid | Less | More | Amino acids | Striking simplicity of amino acids. Glutamic acid and alanine occur in large amounts | All the amino acids are present | Muramic acid | More | Less | Permeablilty of molecules | More penetrable | Less penetrable | Resistance to molecules | Less | More |

List of Gram Negative…...

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