If the mordant was not added when performing the stain, what would then be the Gram reaction of all the cells? Red b/c the crystal violet molecules wouldn’t form a complex (that remains in thick peptidoglycan layer of Gram-positive bacteria) and would be washed away.
What happens if mordant step is skipped?
Mordant step skipped: Gram-positive bacteria will appear Gram-negative. 4. Slide not decolorized: Gram-negative bacteria will appear Gram-positive.
What happens if you forget the mordant in a Gram stain?
If missed, then the bacteria would remain purple and give a false positive result.
What happens when you fail to add iodine to a Gram stain?
Failure to add iodine. The Crystal Violet would be leeched out of everything, because the Iodine is what cross-links with the Crystal Violet. And that cross-link is what help the stain to stay within the cell during decolorization.
What is the purpose of the mordant in Gram staining?
A mordant is a substance that increases the affinity of the cell wall for a stain by binding to the primary stain, thus forming an insoluble complex, which gets trapped in the cell wall. In the Gram stain reaction, the CV and iodine form an insoluble complex (CV-I), which serves to turn the smear a dark purple color.
What would happen if you forgot to add safranin to a gram stain?
A safranin counterstain is used to stain these Gram-negative cells pink. However, if the safranin counterstain were forgotten, the Gram-negative bacteria would remain unstained, as the original crystal violet stain would have been removed during the ethanol wash, and no additional stain would have been applied.
What would happen if you forget to Decolorize a gram stain?
Terms in this set (83) What happens when you decolorize for too long or not long enough? If you leave the decolorizer on too long: gram positive bacteria will come out pink. If you don’t leave it on long enough: gram negative bacteria will come out purple.
What color would gram positive cells be if the mordant is omitted?
Gram-positive cells would be purple.
What would happen if you reversed the order of the mordant and the primary stain with a gram positive bacillus?
What would happen if you reversed the order of the mordant and the primary stain? No staining would occur. The mordant, iodine, would not have anything to bind to. A gram positive reaction gives a pink/red color.
What might happen if you omitted the safranin step while performing?
What might happen if you omitted the safranin step while performing the Gram stain on a mixed culture of gram-positive and gram-negative cells? Gram negative organisms might not be visible.
What are some consequences of leaving a stain on a bacterial smear to long?
The consequences of over-staining the bacterial smear typically result in the loss of the distinct morphological features of the bacterial cells and thus cannot be interpreted easily. Excess staining may degrade the bacterial cell wall and over-strain the entire bacterial slide, reducing accuracy.
What is the purpose of the mordant in Gram staining quizlet?
The mordant used is Iodine. It is added to chemically change the shape of the dye molecule and therefore trap it in the cell wall. Describe differences in staining as they pertain to the differences in the stucture of the cell wall.
What is a mordant in microbiology?
In microbiology, a mordant is a compound used to hold down molecules of a stain onto a microorganism. Classically defined, mordants are usually ions such as metal ions or halide ions, but can be any molecule that serves the purpose of holding down a dye.
What is the function of a mordant and which reagent serves this purpose?
Which reagent serves this purpose in the gram stain procedure? What is the function of a mordant? A mordant intensifies a stain or can be used to coat structures such as flagella for viewing. what type of cell, gram-positive or gram-negative, would you find lipopolysaccharide in its cell wall?
What happens if you leave safranin on too long?
What happens if you leave safranin on too long? Do NOT decolorize for a full minute! If the decolorizer is left on too long, even gram positive cells will lose the crystal violet and will stain red.
Why is safranin necessary?
The safranin is also used as a counter-stain in Gram’s staining. In Gram’s staining, the safranin directly stains the bacteria that has been decolorized. With safranin staining, gram-negative bacteria can be easily distinguished from gram-positive bacteria.
How would each cell appear if you forgot to add safranin?
If the safranin step were skipped, none of the cells would take up a pink color. This would not explain why the Gram-positive cells were pink instead of purple.
What would happen if you forget to add alcohol to a Gram stain?
So if you leave out the alcohol/acetone. The gram negative bacteria will retain their outer cell membrane, and stay purple when your staining is done. Thus both gram positive and negative bacteria will stain purple without the alcohol/acetone step.
What is the importance of Gram staining in microbiology?
A Gram stain is most often used to find out if you have a bacterial infection. If you do, the test will show if your infection is Gram-positive or Gram-negative. A Gram stain may also be used to diagnose fungal infections.
What is the importance of staining in microbiology?
The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.
Why is it important to know whether a bacterium is Gram-positive or Gram-negative?
The main benefit of a gram stain is that it helps your doctor learn if you have a bacterial infection, and it determines what type of bacteria are causing it. This can help your doctor determine an effective treatment plan.
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