Staining

Question 1

Characteristics of Positive (direct) stain:

Answer 1

positively-charged (basic) dye binds to negatively charged cell surface

Question 2

Positive dyes include:

Answer 2

methylene blue, crystal violet, safranin

Question 3

Positive Staining Procedure:

Answer 3

1. loophole of distilled water onto slide, then emulsify a loophole of bacteria onto the slide. SPREAD
2. AIR FUCKIN DRY IT
3. HEAT FIX slide. 5x times. Adhere to the slide
4. Apply few drops of stain to the smear, ONE MIN. COVER THE WHOLE ENTIRE SMEAR
5. gently RINSE with distilled water
6. blot the slide and BOOM. MICROSCOPE

Question 4

Characteristics of Negative Stain:

Answer 4

Negatively charged (acidic) dye is repelled by negatively charged cell surface
no heat fixation required.

Question 5

Negative dyes include:

Answer 5

nigrosin, india ink and congo red

Question 6

Negative Staining Procedure:

Answer 6

1. place a small drop of stain near the end of the slide
2. add a loopful of water to the stain
3. Add bacteria into the mixture
4. EMULSIFY by using the loop to stir the mixture
5. use the end edge of another slide to mix it throughout the slide.
6. AIR FUCKIN DRY IT. then observe

Question 7

What is the purpose of the heat fixation?

Answer 7

cause the bacteria to adhere to the slide and not be rinsed off as easily during the staining process

Question 8

Different shapes and arrangements of Coccus;

Answer 8

cocci- singluar circular
diplococcus- pair
staphlycoccus- clusters
streptococcus - chain like

Question 9

Different shapes and arrangements of Bacillus (rod shaped):

Answer 9

single bacillus
diplobacilli-pairs
streptobacilli- chain-like
coccobacillus-spherical