Simple Stains

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created 5 years ago by OceansVoice
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updated 5 years ago by OceansVoice
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1

2 parts of a stain

1. Solvent (water or ethanol)
2. Chromogen - colored molecule (benzene derivative)

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Chromogen

Colored molecule, usually a benzene derivative

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Chromophore

The portion of the chromogen that gives it its color

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Auxochrome

The charged portion of the chromogen and allows it to act as a dye through ionic or covalent bonds between the chromogen and the cell

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Why does the cell become colored in a basic stain?

Basic stains are attracted to the negative charges on the surface of most bacterial cells thus the cell becomes colored

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Basic stain

Where the auxochrome becomes positively charged as a result of picking up a hydrogen ion or losing a hydroxide ion. Thus, the positively charged chromogen forms an ionic bond with a negatively charged bacterial cell, thus colonizing the cell

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Common basic stains (3)

1. Methylene blue
2. crystal violet
3. safranin

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Heat fixing (4 things it does)

1. Kills bacteria
2. makes them adhere to the slide
3. coagulates cytoplasmic proteins to make them more visible
4. distorts the cells to some extent.

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Emulsion

Bacterial smear

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3 cautions when making a bacterial smear

1. Do not spatter the smear as you mix it
2. Don't blow on or waive the slide to speed up air drying
3. Don't overheat when heat fixing