Why is it important that crystal violet be a contrasting color to safranin? The contrast allows you to differentiate between gram-negative and gram-positive cells by observing the color of the organism.
What is the purpose of crystal violet in Gram staining quizlet?
Crystal violet stains all bacteria in the smear purple; bacteria with thick layers of peptidoglycan in their cell walls (Gram +) retain the purple dye.
What would you anticipate seeing if you accidentally switched crystal violet and safranin?
What would you anticipate seeing if you accidentally switched crystal violet and safranin while performing a Gram stain? All bacteria would appear purple.
Which of the following represents the function of crystal violet in the Gram stain procedure?
Gram Staining
| Table 1. Gram stain process | |
|---|---|
| Gram staining stems | Cell effects |
| Step 1: Crystal Violet primary stain added to the specimen smear | Stains cells purple or blue. |
| Step 2: Iodine mordant, makes the dye less soluble so it adheres to cell walls. | Cells remain purple or blue. |
What would happen if you skipped the safranin step of the 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 is the function of crystal violet solution in the Gram stain if it were omitted How would staining results be affected?
If it were omitted, how would staining results be affected? Iodine is used as a mordant which fixes the dye to whatever it is on/in so that the dye would not get washed away by the alcohol. If iodine was not used the dye would get rinsed off when the alcohol is applied.
What does crystal violet stick to on a bacteria?
The primary stain (crystal violet) binds to peptidoglycan, coloring cells purple. Both gram-positive and gram-negative cells have peptidoglycan in their cell walls, so initially, all bacteria stain violet.
What term best describes the ability to distinguish two separate points that are close together?
define microscope resolution? ability to separate or distinguish small objects that are close together. aka clarity.
Which microscope takes advantage of differences in the refractive indexes of cell structures group of answer choices?
1. Phase contrast microscopy – takes advantage of phase differences in the light beam that are caused by different refractive indexes of components within a tissue.
On which type of microscope is the light reaching the specimen invisible to the human eye?
Fluorescent micro-scopes use ultraviolet radiations whose wavelengths are shorter than those of visible light and are not directly perceptible to the human eye. Electron microscopes use elec-tron beams instead of light rays, and magnets instead of lenses to observe submicro-scopic particles.
Why is crystal violet useful?
Crystal violet is used as a textile and paper dye, and is a component of navy blue and black inks for printing, ball-point pens, and inkjet printers. It is sometimes used to colourize diverse products such as fertilizer, antifreeze, detergent, and leather.
How does crystal violet enhance the visualization of microbial features?
How does crystal violet enhance the visualization of bacterial structure(s)? Using crystal violet enhances the contrast between the microorganism itself and the slide, making the bacteria easier to find. And since bacteria are usually negative, a positive is used (e.g. crystal violet) to stain.
Why crystal violet would not be useful in the negative stain technique?
The large crystal violet-iodine complex is not able to penetrate this tightened peptidoglycan layer, and is thus trapped in the cell in Gram positive bacteria.
What happens if you forget crystal violet?
95% ethanol, because it removes the primary stain (crystal violet) from Gram-negative cells. If missed, then the bacteria would remain purple and give a false positive result.
What would happen if you left out the crystal violet step when performing the Gram stain?
What would happen if you left out the crystal violet when performing the Gram stain? You must heat fix your smear before you perform the acid fast staining technique.
Why might you see crystal violet crystals under the microscope when viewing your Gram stained slide?
Gram’s iodine serves as a mordant. Notice in the image below how it forms an insoluble complex with crystal violet. This helps the crystal violet remain in the gram-positive cells during decolorization.
Why is it important that the primary stain and counterstain be of contrasting colors?
Why is it essential that the primary stain and the counterstain be of contrasting color? So it can be distinguished from each other. Which is the most crucial step in the performance of the Gram staining procedures?
What is the importance of Gram staining?
What is it used for? 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 most important reagent in the Gram stain method?
The primary stain of the Gram’s method is crystal violet. Crystal violet is sometimes substituted with methylene blue, which is equally effective. The microorganisms that retain the crystal violet-iodine complex appear purple brown under microscopic examination.
What is the purpose of safranin in Gram staining?
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.
What color will it appear when simple stained with crystal violet?
With the test, Gram-positive organisms retain the crystal violet stain and appear blue; Gram-negative organisms lose the crystal violet stain and contain only the counter-stain safranin and thus appear red [7].
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