F1. Bacterial smear prep & gram staining

Question 1

A dried preparation of bacterial cells on a glass slide

Answer 1

Bacterial Smear

Question 2

Properly processed smear:

Answer 2

1. evenly spread out
2. bacteria are not washed out during staining
3. bacterial form is not distorted [smears are sterile & bacteria are not killed)

Question 3

Good smears are critical for discerning:

Answer 3

• morphology (shape)
• arrangement (clustering)
• internal structures

Question 4

two loopfuls of liquid containing organisms from culture

Answer 4

Broth cultures

Question 5

two loopfuls of water + very small amount of organism [organism should be emulsified w/ the water]

Answer 5

Plates & Slants

Question 6

use of a single stain to color a bacterial cell

Answer 6

Simple staining

Question 7

• basic dyes because they have color-bearing ionic groups (chromophores) that are positively charged (cationic)
• commonly used dyes in simple staining:

Answer 7

1. methylene blue
2. basic fuchsin
3. crystal violet

Question 8

Coccus?

Answer 8

Spherical

Question 9

four arrangements of coccus shape?

Answer 9

1. diplococcus
2. streptococcus
3. staphylococcus
4. micrococcus

Question 10

pairs?

Answer 10

diplococcus

Question 11

chains coccus?

Answer 11

streptococcus

Question 12

random or grapelike clusters

Answer 12

staphylococcus

Question 13

square groups of four cells

Answer 13

micrococcus

Question 14

rod-shaped?

arrangement of this shape?

Answer 14

bacillus

streptobacillus

Question 15

chains bacillus

Answer 15

streptobacillus

Question 16

spiral shaped?

arrangement of this shape?

Answer 16

spirillum

sarcina

Question 17

cubical packets of eight cells

Answer 17

spirillum

Question 18

incomplete spiral shape?

Answer 18

vibrio

Question 19

irregular or variable shape?

Answer 19

pleomorphic

Question 20

it has two kinds of cells:
gram positive & gram negative

1. stained purple
2. stained red/pink

Answer 20

Gram staining

1. gram positive
2. gram negative

Question 21

cultures should be ____ hours old…

Answer 21

16-18

Question 22

critical step in gram staining procedure?

Answer 22

prepare thin smears

Question 23

most critical step in gram staining procedure?

Answer 23

decolorization

Question 24

what separates the organism that will be stained

Answer 24

decolorization

Question 25

reagents used in gram staining?

Answer 25

1. crystal violet 2. gram's iodine 3. acetone alcohol 4. safranin

Question 26

- primary stain - color gram negative organisms - stand for 30 seconds

Answer 26

crystal violet

Question 27

- mordant - help enhance primary stain - stand for 1 minute

Answer 27

gram's iodine

Question 28

- decolorizer - color gram positive organisms @ a 45 degree angle for not more than 15 seconds ## Footnote decolorizers are?

Answer 28

Acetone alcohol ## Footnote colorless

Question 29

- secondary stain - will stain other gram organisms - stand for 1 minute

Answer 29

safranin