Specimen Staining Flashcards
<p>
| Why do we stain and fix specimen?</p>
<p>
| Most microorganisms are transparent and move quickly.</p>
<p>Why do we use basic dyes in simple staining? </p>
<p>The bacterial cell wall, nucleic acids, and oter cell structures are negatively charged, so a positively charged basic dye will be attracted to the bacteria. </p>
<p>What are 4 common basic dyes? </p>
<p>1. Crystal Violet
2. Methylene Blue
3. Safrinin (Red)
4. Malachite Green</p>
<p>How is a simple stain performed? </p>
<p>1. Drop of microorganism-containing liquid dropped onto slide.
2. Organisms are fixed (via heat)
3. Dye is applied, then washed off with water.</p>
<p>What are the characteristics of a simple stain? </p>
<p>1. Increases contrast between cells and background.
| 2. All cells stained the same color (no differentiation between cell types)</p>
<p>What is the purpose of a differential stain? </p>
<p>Used to distinguish one bacterial group from another.</p>
<p>What are the two most common differential stains ?</p>
<p>1. Gram Stain
| 2. Acid-fast stain</p>
<p>What are 3 special stains used to observe cell structure? </p>
<p>1. Capsule stain
2. Endospore stain
3. Flagella stain
</p>
<p>What is the most widely used procedure for staining bacteria? </p>
<p>The Gram stain</p>
<p>What are the 4 reagents used in performing a Gram stain? What are their purposes? </p>
<p>1. Crystal violet (Primary Stain)- Stains all cells
2. Gram's Iodine (Mordant)- glues CV to call wall
3. Alcohol (Decolorizer)- removes stain from G- bacteria
4. Safrinin (Secondary Stain/ Counter stain)- recolorizes G- bacteria. </p>
<p>What result would you expect from properly performing a Gram stain? </p>
<p>G+ bacteria would be stained purple, and G- bacteria would be stained pink. </p>
<p>Which genus is the Acid-Fast stain useful in staining, and why? </p>
<p>Mycobacteria have a high lipid concentration that resists Gram staining. Applying the acid-fast stain with heat allows Mycobacteria to be stained for viewing. </p>
