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It allows the primary stain crystal violet to remain in the cell instead of being washed out. Due to the larger size of the crystal violet molecule, when the ethanol is applied (the decolorizer) the stain will not be washed out of the Gram (+) positive cells.

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What are the reagents and steps min a Gram stain?

The steps in Gram staining are:1. crystal violet added to the smear2. iodine, the mordant (this fixes the violet)3. a decolorizer made of acetone and alcohol4. safranin, the counterstainIf the cell is Gram +, the decolorizer can not remove the violet. If it is Gram -, the decolorizer can remove the violet and the cell can be then colored with the dye, safranin.Bacteria are grouped in 4 groups by Gram stain:Gram-positive, the cell wall retains crystal Violet.Gram-negative, the cell wall does not retain crystal Violet.Graham not reactive, no staining whatsoever.Graham variable, uneven staining.


Can grams iodine be used before primary stain?

Probably not. The CVI complex formed between the iodine and crystal violet will be trapped in the lipid layer and not the peptidoglycan layer, so you would probably end up over decolorizing. This would cause a lot of false gram negatives. Probably not. The CVI complex formed between the iodine and crystal violet will be trapped in the lipid layer and not the peptidoglycan layer, so you would probably end up over decolorizing. This would cause a lot of false gram negatives.


Do acid-fast bacteria stain gram-negative when subjected to the gram stain?

No, acid-fast bacteria do not stain gram-negative when subjected to the gram stain.


List the steps of the gram-staining procedure in order and fill in the color of gram-positive cells and gram-negtive cells after each step?

____________Color of Gram-positive_______Color of Gram-negativePrimary stainCrystal violet_____Purple____________________ PurpleMordant:Iodine____________Purple________________________PurpleDecolorizing agent:Alcohol-acetone__ Purple____________________ ColorlessCounterstain:Safranin___________Purple_________________________Red


What will be the color of the gram positive if iodine step left out?

Since you've missed the iodine step and you're going to put a decolorizer(alcohol) into it for the next step , naturally it will lost it's color. Because iodine acts as a mordant, which means it helps the gram positive to retain it's color.

Related Questions

What function of iodine in gram stain?

fixing the stain so that the first dye which is the crystal violet will not be washed away during rinse process.


What color is gram negative stain and gram positive stain if you forget to apply iodine?

If iodine is not applied, both the gram-positive and gram-negative stains will appear to be gram-negative. The iodine acts as a mordant that helps to fix the crystal violet stain in the gram-positive bacteria, making them appear purple. Without iodine, the crystal violet stain can be easily washed out of both gram-positive and gram-negative bacteria, resulting in a pink or red color.


Is iodine a basic stain?

No, iodine is not a basic stain. Iodine is commonly used in Gram staining to identify bacteria as either Gram-positive or Gram-negative based on their cell wall composition. It acts as a mordant in the staining process and helps to fix the crystal violet stain in Gram staining.


Why do you use iodine to stain a cell?

Iodine is used to stain cells because it binds to glycogen and starch, making them more visible under a microscope. This helps to visualize the cellular structures and identify specific components within the cell.


What is the difference between lugols iodine and grams iodine?

Lugol's iodine is a mixture of elemental iodine and potassium iodide, commonly used as a disinfectant and as a supplement to support thyroid function. Gram's iodine, on the other hand, is a stain used in microbiology to differentiate between gram-positive and gram-negative bacteria based on their cell wall composition. The main difference lies in their applications and compositions.


What is the action of iodine in grams stain?

Iodine is used to bind the Crystal Violet to the Gram Positive microbes.


What function of lugol's iodine in gram staining?

fixing the stain so that the first dye which is the crystal violet will not be washed away during rinse process.


Why gram's iodine called a mordant?

Gram's iodine is called a mordant because it fixes the primary stain to the cell wall and adds any color.


What is the secondary stain in gram stain procedure?

It is crystal violet & stains all cells purple.


What is the importance of iodine after primary stain?

Iodine is used after the primary stain in the Gram stain procedure to form a complex with the crystal violet dye, which helps to stabilize the dye within the bacterial cell wall. This step enhances the retention of the primary stain in Gram-positive bacteria.


What is the function of sodium bicarbonate with Merthiolate in Gram stain?

Sodium bicarbonate is used to adjust the pH of the staining solution in the Gram stain procedure. Merthiolate is used as a mordant to enhance the crystal violet staining in the Gram stain. Together, they help differentiate between Gram-positive and Gram-negative bacteria based on their cell wall characteristics.


What are the reagents and steps min a Gram stain?

The steps in Gram staining are:1. crystal violet added to the smear2. iodine, the mordant (this fixes the violet)3. a decolorizer made of acetone and alcohol4. safranin, the counterstainIf the cell is Gram +, the decolorizer can not remove the violet. If it is Gram -, the decolorizer can remove the violet and the cell can be then colored with the dye, safranin.Bacteria are grouped in 4 groups by Gram stain:Gram-positive, the cell wall retains crystal Violet.Gram-negative, the cell wall does not retain crystal Violet.Graham not reactive, no staining whatsoever.Graham variable, uneven staining.