fixing the stain so that the first dye which is the crystal violet will not be washed away during rinse process.
Iodine is used as a mordant in the gram staining procedure to make large crystals when it is used with crystal violet dye. In gram positive cell walls those crystals get stuck and wont get washed off with the alcohol. In gram negative cell walls the crystals are washed out.
Gram's iodine stain is applied after the culture is stained with the primary stain. It acts as a mordant, fixing the primary stain to the cell wall while lending no additional colour to the cell (i.e. the mordant itself is not a stain). The mordant is only able to fix the stain to Gram-positive bacteria because of the characteristic thick, peptidoglycan coat that they possess. Because the mordant is not able to fix the stain to Gram-negative bacteria (who's coat have a different composition), the crystal violet stain will wash away from Gram-negative bacteria when the decolourizing agent is added.
No. It is a staining on the cell itself.
as a couterstain
step 1 crystal violet step 2 grams iodine step 3 ethanol step 4 safranin
Iodine is added as a mordant to enhance crystal violet staining by forming a crystal violet-iodine complex.
In Gram staining procedure during bacterial staining , iodine forms a complex with crystal violet stain which stains Gram positive bacteria blue to violet .
Iodine is used as a mordant in the gram staining procedure to make large crystals when it is used with crystal violet dye. In gram positive cell walls those crystals get stuck and wont get washed off with the alcohol. In gram negative cell walls the crystals are washed out.
iodine act as a mordant..on the gram positive bacteria which got really thick and abundence of peptidoglycan layer, the crystal violet will fix to the peptidoglycan layer..meanwhile in gram negative bacteria which is lack of peptidoglycan layer, the alcohol or acetone will wash it away
Lugol's Iodine = 20g Potassium Iodide + 10g Iodine dissolved in 1L H2O Gram's Iodine = 6.7g potassium iodide + 3.3g Iodine dissolved in 1L H2O Recipe's taken from Flinn Scientific Catalog I have on campus. Looks to me as Gram's is just a dilute version of Lugol's. Same ratio of KI:I just less of it. Couldn't tell you much about differences in application however.
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.
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.
Thomas Francis McNamara has written: 'Iodine and the quantitative gram reaction' -- subject(s): Iodine, Stains and staining (Microscopy)
It is used in gram staining to differentiate gram negative and gram positive bacteria. After being dyed, the cells are washed with ethanol. Gram positive bacteria will retain the methylene blue due to the amount of peptidoglycan in their cell walls, where gram negative cells will not. Iodine is used as a counter stain, which is up-taken by gram negative cells. After the gram staining procedure is finished, gram positive cells will appear dark purple or blue due to the retained methylene blue. Gram negative cells will appear pink or red due to the iodine counter stain.
Gram's iodine stain is applied after the culture is stained with the primary stain. It acts as a mordant, fixing the primary stain to the cell wall while lending no additional colour to the cell (i.e. the mordant itself is not a stain). The mordant is only able to fix the stain to Gram-positive bacteria because of the characteristic thick, peptidoglycan coat that they possess. Because the mordant is not able to fix the stain to Gram-negative bacteria (who's coat have a different composition), the crystal violet stain will wash away from Gram-negative bacteria when the decolourizing agent is added.
Perhaps Gram Staining? Steps are as follows: 1. Crystal Violet, 2. Iodine, 3. Decolorizer, 4. Safrinin
No. It is a staining on the cell itself.