Part 3

Question 1

Stains are solutions consisting of a solvent (usually water or ethanol) and a colored molecule (often a benzene derivative), the _______.

A.) auxochrome

B.) chromogen

C.) chromophore

D.) basic stains

Answer 1

B.) chromogen

Question 2

The portion of the chromogen that gives it its color is the _______.

A.) auxochrome

B.) chromogen

C.) chromophore

D.) basic stain

Answer 2

C.) chromophore

Question 3

The _______ is the charged portion of a chromogen and allows it to act as a dye through ionic or covalent bonds between the chromogen and the cell.

A.) auxochrome

B.) chromogen

C.) chromophore

D.) basic stain

Answer 3

A.) auxochrome

Question 4

_______ (where the auxochrome becomes positively charged as a result of picking up a hydrogen ion or losing a hydroxide ion) are attracted to the negative charges on the surface of most bacterial cells.

A.) auxochrome

B.) chromogen

C.) chromophore

D.) basic stain

Answer 4

D.) basic stain

Question 5

Basic stains are applied to bacterial smears that have been _______.

This kills the bacteria, makes them adhere to the slide, and coagulates cytoplasmic proteins to make them more visible. It also distorts the cells to some extent.

Answer 5

Heat-fixing

Question 6

Upon successful completion of a Gram stain, Gram-positive cells appear _____ and Gram-negative cells appear ______.

Answer 6

Gram-positive cells appear purple

Gram-negative cells appear reddish-pink

Question 7

What is the process for performing a Gram stain?

Answer 7

1.) Begin with a heat-fixed emulsion

(use slide holder)

2. ) Crystal Violet Stain for 1 minute
3. ) Rinse with DI water
4. ) Gram’s iodine for 1 minute
5. ) Rinse with DI water
6. ) Decolorize with alcohol for no more than 10 seconds
7. ) Rinse with DI water
8. ) Safranin for 1 minute
9. ) Rinse with DI water
10. ) Bibulous paper

Question 8

What are the steps for performing an acid-fast stain?

(Ziehl-Neelson Method)

Answer 8

1. ) Start a hot water bath!!!!!!
2. ) Prepare a smear of organism. Air dry and then heat fix.
3. ) Cover the smear with a strip of bibulous paper.
4. ) Once water is boiling, use slide holder and add ZN Carbolfuschin stain for 5 minutes. (keep it moist)
5. ) Once 5 minutes are up, properly dispose of bibulous paper
6. ) Rinse with DI water
7. ) Decolorize with acid-alcohol until the runoff is clear
8. ) Rinse with DI water
9. ) Counterstain with Methylene blue for 1 minute.
10. ) Rinse with DI water
11. ) Gently blot dry with bibulous paper

Question 9

Upon completion, acid-fast cells are _______;

nonacid-fast cells are the color of the counterstain.

Answer 9

Upon completion, acid-fast cells are reddish-purple;

nonacid-fast cells are the color of the counterstain.