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General Microbiology BIOL 455 - OpenStax CNX

cnx.org
Clayton Wintermantel Clayton Wintermantel
2 months ago
Unique Characteristics of Prokaryotic Cells
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Learning Objectives
1.)Common cell morphologies and Arrangements
2.)Nucleoids
3.)Plasmids
Ribosomes
Inclusions
Endospores
Plasma Membrane
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Some
Inclusions that aren't for nutrient storage.
A.) Gas Vacuoles
B.) Magnetosomes
C.) Carboysome
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eth
3H2O
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Staining Microscopic Specimens | Microbiology

courses.lumenlearning.com
Clayton Wintermantel Clayton Wintermantel
2 months ago
Objectives:
Explain the procedures and name clinical applications for Gram, endospore, acid-fast, negative capsule, and flagella staining.
Gram-staining
Objectives:
Explain the procedures and name clinical applications for Gram, endospore, acid-fast, negative capsule, and flagella staining
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Acid-fast staining
Acid-fast stain
Distinguishes bacteria based on cell wall properties.
Acid-fast bacteria
Gram-positive
Resistant to the Gram stain
Have mycolic acid in their
cell walls
Have polymers (arabinogalactan/lipoarabinomannan)

Mycolic Acid
Waxy substance
Part of the Acid Fast bacterial cell wall


Overview of acid-fast staining process:
1. primary stain - fuchsin + heat
3. decolorizer - acid alcohol
4. counterstain - methylene blue


of fuchsin in staining
Primary stain
Needs heat
All cells will take up the reddish-pink primary stain.


What is found in Carbol Fuchsin?
Phenol. Solubilizes the cell wall and allow the stain to enter the cell


Why must heat be used with the application of the primary stain during acid-fast staining?
To allow the stain to penetrate the waxy cell wall

of Acid Alcohol in Acid-fast staining procedure.
Decolorizer
Decolorizes all cells except acid-fast cells.
acid alcohol is unable to penetrate mycolic acid


Function of the Methylene Blue in
Counterstain
stains the decolorized cells blue.


of staining:
Acid-fast cells: Pink/red
organisms: blue






When and why would the acid-fast stain be used in a hospital or clinical lab?
To determine if the patient has or TB


What is the main chemical found in the cell walls of mycobacteria and Nocardia?
Mycolic Acid on its cell wall


List the 3 chemicals used in the Acid Fast stain.
fuchsin
acid alcohol
methylene blue


How is the decolorizer in the Acid Fast stain different than in the Gram stain?
In stain: acid alcohol
In Gram stain: 95% ethanol


Name the acid-fast organism used
Mycobacterium
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; the cells should still be classified as gram-positive if they are all the same species rather than a mixed culture.
Remember this, even if some of the cells appear to be Safranin (gram -)
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acid-fast stain
Gram positive was to differentiate between gram positive and gram negative (cell wall differences.)
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