Chapter 3: Lab techniques

01/22/2025- finished flashcard set ~ X

What is “staining”?

The use of dyes- such as basic or acidic dyes- to create contrast by imparting color on bacteria slides.

What are the two types of dyes used in staining?

Basic and acidic dyes

Basic dyes

Has a cationic charged chromophore and is used for positive staining (microbe staining).

Acidic dyes

Has a anionic charged chromophore and is used for negative staining (background staining).

What does the simple stain show?

Shows shapes, size, and arrangement of bacteria.

What does the differential stain show?

Shows distinguished cell types. Uses 2 dyes and includes stains such as Gram, acid-fast, and endospore.

What are the three different types of differential stains?

• Gram stain

• Acid-fast stain

• Endospore stain

Does the gram stain pertain to bacteria charge?

Yes

What is the color of a positive gram stain?

purple

What is the color of a negative gram stain?

pink

What is the primary and counterstain in the gram stain?

primary is crystal violet and counterstain is Safranin

What color would a positive acid fast stain be?

Bold pink

What color would a negative acid fast stain be?

Dark blue

What color would a endospore stain be?

Greenish blue

What color would a vegetative cell on an endospore stain be?

Pinkish red

What kind of stain would be used to see cell parts like capsules and flagella?

Structural/Special stains

Is media sterile?

Yes

Compare mixed VS pure culture

• Mixed- more than one microbe growing in sample or culture medium.

• Pure- one microbe growing in culture medium.

What temperature are the incubators set at?

37 degrees Celsius

In what 2 ways can media be classified as?

Physical form and functional type

What are the 3 physical forms of culture media?

• Liquid- ex. nutrient broth

• Semisolid- ex. motility agar

• Solid- ex. nutrient agar

What are the 3 functional types of media?

• Enriched- Supports the growth of fastidious species (ex.blood agar, chocolate agar)

• Selective- Encourage growth of select microbial groups while inhibiting the growth of others. (ex. Mannitol salt agar, MacConkey agar)

• Differential- Allows the growth of several microbial species while displaying visible different among the microbes.

What is the highest magnification of a light microscope?

2000x

What are the types of scopes used in class?

Light microscopes

Label each objective lens on a light microscope from lowest to highest order.

• Scanning (4x)

• Low-power (10x)

• High-power (40x)

• Oil immersion (100x)

What is the magnification of the ocular lenses?

10x