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Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with. If the violet can be washed out and the counter stain (pink) is added, the bacteria are Gram-.
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Which is the Counterstain used in PAS staining?
The counterstain for PAS is hematoxylin which stains nucleic acids blue.
Could other dyes be used as a counterstain?
no
What microscopic structure other than bacteria can be gram stained?
This process is used as a screening test for bacteria only.
What is stained with primary dye?
Bacterial smears that are undergoing some type of differential staining method are stained with a primary dye. Primary dye typically refers to a Crystal-voilet stain that is used in the gram staining procedure to color all cells purple. After a mordant (iodine-makes the dye complex less soluble), decolorizer, and a counterstain are added to the primary dye, a person can view the slide under a microscope in order to distinguish gram-positive bacteria from gram-negative bacteria. The cell wall of gram-negative bacteria will not retain the primary dye and be washed away with the decolorizer. Gram-neg. bacteria will then take on the counterstain providing contrast between the two types of bacteria when viewed under a microscope.
What happen if you forget to add crystal violet to a stain?
You don't get a counterstain.
Which is the Counterstain used in PAS staining?
The counterstain for PAS is hematoxylin which stains nucleic acids blue.
What is the meaning of stain for?
meaning of counterstain
Could other dyes be used as a counterstain?
no
What dye is used in counterstain?
i wouldn't have asked you if i know it
Why is it essential that the primary stain and the counterstain be of contrasting colors?
It is essential that primary stain and the counterstain be of contrasting colors so that the target of the primary stain can easily be differentiated on a contrasting background.
What microscopic structure other than bacteria can be gram stained?
This process is used as a screening test for bacteria only.
What structure in the cheek cells was stained the darkest?
When stained with iodine and observed under a compound microscope the nucleus will stain the darkest. The cheek cell is frequently employed here as they are simple to collect and tend to take the stain easily.
What happen if you forget to add crystal violet to a stain?
You don't get a counterstain.
What is stained with primary dye?
Bacterial smears that are undergoing some type of differential staining method are stained with a primary dye. Primary dye typically refers to a Crystal-voilet stain that is used in the gram staining procedure to color all cells purple. After a mordant (iodine-makes the dye complex less soluble), decolorizer, and a counterstain are added to the primary dye, a person can view the slide under a microscope in order to distinguish gram-positive bacteria from gram-negative bacteria. The cell wall of gram-negative bacteria will not retain the primary dye and be washed away with the decolorizer. Gram-neg. bacteria will then take on the counterstain providing contrast between the two types of bacteria when viewed under a microscope.
Which structure in a stained cheek cell would most likely be visible when viewed through the high-power objective of a compound microscope?
nucleolus
Why is counterstaining necessary when using a differential staning technique such as the gram stain?
The counter-stain allows you to see all the structures that were not stained with the primary stain. Without the counter-stain, all you would see is the purple-stained structures (nucleus, some cytoplasmic proteins), but you would have a difficult time observing the cell membrane and many cytoplasmic structures.
Which step of a gram stain can be omitted without affecting determination of the reaction?
you can omit the last step - the safranin counterstain
