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Flashcards in Bacterial Visualization, Growth and Control Deck (112)
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1

resolution is more important than _____

magnification

2

stain increases ____________

contrast

3

contrast increases _______

resolution

4

visualizing bacteria depends on (3)

magnification, contrast, resolution

5

sample fixation (def)

secures sample to slide before staining
kills sample
eliminates movement

6

sample fixation types

heat fixation
chemical fixation

7

heat fixation

dry sample on slide, pass sample/ slide through flame
denatured proteins in sample adhere sample to slide

8

chemical fixation

less damaging that heat
use for delicate samples (flagella, formalin)

9

basic stain

most common
positive ion colored
binds negatively charged cell surface

10

acidic (negative) stain

negative ion colored
stain repelled from negatively charged cell surface
ink darkens background around cell to show cell shape, arrangement

11

basic stain examples

safranin, carbolfuschin, crystal violet, methylene blue, malachite green

12

acidic (negative) stain example

nigrisin
india ink

13

mordant

not a stain
iodine (negative ion, heat

14

mordant function

increases affinity for stain, enhancing cell staining
increases visibility of external cell walls, flagella

15

staining techniques (3)

vital
simple
differential

16

vital stain

stains living sample
adds color to wet mount and hanging drop preparations
no heat fixation

17

simple stain

1 stain
stains all cells same color
methylene blue, crystal violet

18

differential stain

distinguishes 2 different species in sample
2 stains

19

differential stain types (5)

Gram stain
acid fast stain
endospore stain
capsule stain
flagella stain

20

4 steps to a differential stain

1. primary stain- stains all species same color
2. mordant
3. destaining
4. counterstain

21

Gram stain

distinguishes Gram positive bacteria (blue) from Gram negative (pink)

22

Gram stain steps

Start with heat fixed sample.
primary stain- crystal violet 1 min, rinse H20, mordant- iodine 1 min, rinse H20, Destain with acetone 5-10 seconds, rinse with water. Counterstain with safranin 3 min, rinse with water. Blot.

23

acid fast stain

stains Mycobacterium red
all others blue after counterstain

24

acid fast stain steps

primary stain carbolfucshin, heat slide to steaming (mordant) destain with alcohol- only Mycobacterium retain red. Counterstain with methylene blue.

25

endospore stain

stains endospores in their resistant stage, able to survive harsh conditions
ex Bacillus, Clostridium
endospores appear blue/green inside of pink cells

26

endospore stain steps

primary stain malachite green, heat (mordant) destain with water, counterstain with safranin

27

capsule stain

shows shape, arrangement of cells, thickness of capsule
ink is repelled from capsule surface so the cells appear white against black background
Klebsiella, Cryptococcus

28

capsule stain steps

primary stain India ink, counterstain methylene blue

29

flagella stain

requires gentle chemical fixation without heat
shows number and arrangement of flagella

30

pure culture

contains single species, not a mixture
derived from a single cell
colonies must not touch other colonies on plate to be certain culture is pure