Biological Stains Discussion

Stain:

          Define

          Chemical Composition

          Types

          Use

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·       organic chemical compound that is fixed to a specimen to impart color for visibility and identification

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Chemical Composition:

* Benzene (organic solvent)

   Chromophore (color)       

   Auxochrome (ionizes)

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Types:

1.    Acidic

          Looses H+ to become negative = anionic

         Negative charge attracted to + cell parts [proteins]

          e.g. Nigrosin, India Ink, Acid Fuscin

2.    Basic

          Looses (-) such as Cl- to become positive = cationic

          Positive charge attracted to – cell parts [nucleus]

          e.g. Methylene Blue, Crystal Violet, Carbol Fuscin

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Use:

          Simple Stain

-         Single Stain

-         Observe morphology and arrangement

-         Basic stains primarily used since Bacteria are – charged

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          Differential Stain

-         2 (or more) stains

-         Contrast groups and classify structures

-         Basic stains of different color used

-         Several Types: Gram, Capsule, AF, Spore, Flagella