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because the outer membrane is phospholipid bi layer, which is positive charged one.
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Why is the technique called negative staining?
Because the cell wall repels the binding of the negative stain therefore the cells do not stain. Because of this the background is stain with the dye used and the bacteria remain colorless. Basically your staining the background, that is, you are not directly staining the cells.
Why cant methylene blue be used in place of nigrosin in negative staining?
Because negative staining requires the use of an acidic stain, which will not penetrate the cells because of the negative charge on the surface of the bacteria. As a result, the unstained cells can be easily identified against the colored background.
Describe the microscopic appearance of encapsulated streptococcus if stained with safranin?
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
Cite the purpose of following reagents in a differential staining procedure?
To distinguish between acid fast positive and acid fast negative bacteria. Acid fast positive bacteria will stain red to pink color and acid fast negative bacteria will stain blue. Acid fast positive bacteria have mycolic acid in their cell wall, which will stain with carbol fuchsin and not decolorize with acid alcohol. Acid fast negative bacteria do not have mycolic acid in their cell wall, and become decolorize with the acid alcohol. Counterstain of methylene blue needs to be done in order to see the acid fast negative.
Purpose of decolorizing agent?
The decolorizer, usually acetone or alcohol, is used to wash the Crystal Violet stain from the Gram Negative cells. From this point Safranin stain is used to stain the Gram Negative cells. The final color for Gram Negative will be a Red/Pink color.
Why is the technique called negative staining?
Because the cell wall repels the binding of the negative stain therefore the cells do not stain. Because of this the background is stain with the dye used and the bacteria remain colorless. Basically your staining the background, that is, you are not directly staining the cells.
Why cant methylene blue be used in place of nigrosin in negative staining?
Because negative staining requires the use of an acidic stain, which will not penetrate the cells because of the negative charge on the surface of the bacteria. As a result, the unstained cells can be easily identified against the colored background.
What are the advantages of the simple stain technique over the negative stain technique?
Negative staining has a dark contrasted background and the bacteria is white. Simple staining has a white background and bacteria is the color depended on your stain color.Negative staining when prepared is NOT heat fixed but simple staining when prepared is heat fixed. Heat fixed means when preparing slide with bacteria on it, it is passed over some type of flame, like a Bunsen burner flame, three times or four times.
Why is size more accurate in an acidic or negative stain than in a simple or basic stain?
Since there is no heat fixing or strong cemicals are used the bacteria are less distorted
Describe the microscopic appearance of encapsulated streptococcus if stained with safranin?
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
What is a negative stain?
The negative staining techniques uses a dye solution in which the chromogen is acidic and carries a negative charge. (An acidic chromogen gives up a hydrogen ion, which leaves it with a negative charge.) The negative charge on the bacterial surface repels the negatively charged chromogen, so the the cell remains unstained against a colored background.
What is gram positive strain?
Gram-positive bacterium are those that are stained dark blue or violet by Gram Staining. This is in contrast to Gram-Negative Bacterium, which cannot retain the crystal violet stain, instead taking up the counter-stain and appearing red or pink. Gram-positive organisms are able to retain the crystal violet stain because of the high amount of peptidoglycan in the cell wall. Gram-positive cell walls typically lack the outer membrane found in Gram-negative bacteria.
Cite the purpose of following reagents in a differential staining procedure?
To distinguish between acid fast positive and acid fast negative bacteria. Acid fast positive bacteria will stain red to pink color and acid fast negative bacteria will stain blue. Acid fast positive bacteria have mycolic acid in their cell wall, which will stain with carbol fuchsin and not decolorize with acid alcohol. Acid fast negative bacteria do not have mycolic acid in their cell wall, and become decolorize with the acid alcohol. Counterstain of methylene blue needs to be done in order to see the acid fast negative.
What is the gram stain of H5N1?
The Gram stain is used for bacteria and not for viruses.
Purpose of decolorizing agent?
The decolorizer, usually acetone or alcohol, is used to wash the Crystal Violet stain from the Gram Negative cells. From this point Safranin stain is used to stain the Gram Negative cells. The final color for Gram Negative will be a Red/Pink color.
What counter stain is used in gram staining?
safranin
Carbolfuchsin can be used as a simple stain and as a negative stain as a simple stain the pH is?
8
