Chapter 4 lecture notes Flashcards Preview

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Flashcards in Chapter 4 lecture notes Deck (24):
1

Stains are dyes made of?

Organic salts

2

Dyes carry ___ or ___ _____ on the molecule. The molecule binds to?

(+) or (-) charge
Certain cell structures

3

Dyes divided into _____ or _____ based on charge

basic or acidic

4

These dyes carry positive charge and bond to cell structures that carry negative charge

Basic dyes

5

* Commonly stain the cell
* Simple stains are these dyes which are simple to use
– Simply soak a smear and rinse off

Basic dyes

6

These dyes carry negative charge and are repelled by
cell structures that carry negative charge

Acidic

7

* Commonly stain the background
* Negative stains are these dyes

Acidic dyes

8

Common basic dyes include

– Methylene blue
– Crystal violet
– Safranin
– Malachite green

9

Uses one basic stain to stain the cell

Simple stain

10

* Allows for increased contrast between cell and background
* All cells stained the same color
-no differentiation between cell types

Simple stain

11

* Used to distinguish one bacterial group from another
* Uses a series of reagents

Differential stains

12

Two most common differential stains

* Gram stain
* Acid-fast stain

13

Most widely used procedure for staining bacteria

Gram stain

14

– Developed over century ago
– Dr. Hans Christian Gram

Gram stain

15

Bacteria separated into two major groups

Gram stain. The two groups are Gram positive (Stained purple) and Gram negative (stained pink)

16

The Gram stain involves four reagents

1) Primary stain- crystal violet, stains all cells
2) Mordant- Grams iodine
3) Decolorizer- usually alcohol, removes primary dye from gram negative cell
4) Counter or secondary stain- Safranin, recolors cells that lose stain through decolorization

17

Used to stain organisms that resist conventional staining

Acid fast stain

18

Used to stain members of genus Mycobacterium (High lipid (wax) concentration in cell wall prevents uptake of dye)

Acid-fast stain

19

* Uses heat to facilitate staining
* Once stained difficult to decolorize

Acid-fast stain

20

Can be used for presumptive identification in diagnosis of clinical specimens

Acid fast stain

21

Acid fast staining requires multiple steps

1) Primary dye- Carbol fuchsin, colors acid-fast bacteria red
2) Decolorizer- Generally acid alcohol, removes stains from non acid-fast bacteria
3) Counter stain- Methylene blue, colors non acid-fast bacteria blue

22

* Example of negative stain
* Only stains the background
* Allows capsule to stand out around organism

Capsule stain

23

* Staining enhances endospore
* Uses heat to facilitate staining

Endospore stain

24

* Staining increases diameter of flagella
* Makes them more visible

Flagella stain