Staining!!

Question 1

What are stains made up of? (think ions)

Answer 1

A positive and negative ion. ( one of these ions are the colored–> called chromophore)

Question 2

In these dyes, the chromophore is a cation.
-stains negatively charged molecules

Answer 2

Basic dye

Question 3

In these dyes, the chromophore is an anion.
- stains positively charged molecules

Answer 3

Acidic dye

Question 4

Using a single basic dye and possible a mordant.
what type of stain?

Answer 4

Simple stain

Question 5

What is a mordant?

Answer 5

A substance used to hold the stain or enhance the stain ability to coat the specimen.

Question 6

Stains background, not specimen

Answer 6

Negative stain

Question 7

Type of stain used to distinguish between bacteria

Answer 7

Differential stains

Question 8

What are the differential stains?

Answer 8

1. Endospore staining (spore/ no spore)
2. Gram staining (gram- or gram+)
3. Acid-fast staining (mycolic acid +/mycolic acid-)
4. Capsule/Negative Staining

Question 9

Which bacteria stain gram +? What cell structure/features are being targeted?

Answer 9

Bacteria with thick peptidoglycan walls are gram+

Question 10

Which bacteria stain gram -? What cell structure/features are being targeted?

Answer 10

Bacteria with thin peptidoglycan walls and layer of lipopolysaccharides.

Question 11

What color do gram + bacteria stain?

Answer 11

Purple

Question 12

What color do gram - bacteria stain?

Answer 12

Red

Question 13

What are acid-fast stains targeting in specimen’s cells?

Answer 13

The presence of mycolic acid, a waxy material in the cell walls. This mycolic acid does not become decolorized after acid-alcohol.

Question 14

What color do mycolic acid + bacteria stain?

Answer 14

Red ( it is not decolorized by alcohol because of the mycolic acid)

Question 15

What color do mycolic acid - bacteria stain?

Answer 15

Blue (it is decolorized and picks up the methylene blue)

Question 16

What is negative staining used for?

Answer 16

For seeing capsules in bacteria

Question 17

Why is it necessary to use negative staining for capsulated bacteria? Why not use regular staining processes?

Answer 17

The capsule have a gelatinous covering that does not accept most dyes.

Question 18

In endospore staining, it is necessary to bake the malachite green into the endospores. Why? Why aren’t other staining methods effective at visualizing the endospores?

Answer 18

Endospores are created to resist extreme conditions. They resist a lot of stains.

Question 19

What are endospore cells expected to look like under the microscope?

Answer 19

They are expected to look like red cells(safranin) with a green endospore (malachite green).

Question 20

What is another name for negative staining? think purpose

Answer 20

Capsule Staining