BMSC210 CH2.4

Question 1

What is the purpose of staining microscopic specimens?

Answer 1

To provide color and contrast for detecting cellular structures

Question 2

What are the two types of stains?

Answer 2

Simple and differential stains

Question 3

Name five staining procedures and their clinical applications.

Answer 3

Gram, endospore, acid-fast, negative capsule, and flagella staining

Question 4

What are the two basic types of preparation used to view specimens with a light microscope?

Answer 4

Wet mounts and fixed specimens

Question 5

What is a wet mount?

Answer 5

A specimen placed on a slide in a drop of liquid

Question 6

How can solid specimens be prepared for a wet mount?

Answer 6

Placed on the slide before adding a drop of liquid

Question 7

What are common liquids used to prepare specimens for light microscopy?

Answer 7

Water or stained liquids

Question 8

What is the purpose of adding stains to specimens?

Answer 8

To enhance contrast

Question 9

What is the next step after adding the liquid to the slide?

Answer 9

Placing a coverslip on top

Question 10

What is fixation in the context of preparing specimens for light microscopy?

Answer 10

Process of attaching cells to a slide

Question 11

How is fixation achieved?

Answer 11

Through heating or chemical treatment

Question 12

Besides attaching the specimen to the slide, what other effect does fixation have on microorganisms?

Answer 12

It kills them and stops their movement and metabolism

Question 13

What are some common chemical fixatives used for tissue specimens?

Answer 13

Acetic acid, ethanol, methanol, formaldehyde (formalin), and glutaraldehyde.

Question 14

What is formalin used for in specimen fixation?

Answer 14

Chemical fixation to preserve tissue structure

Question 15

What is staining used for?

Answer 15

To color certain features of a specimen before examining it under a light microscope.

Question 16

What are stains made up of?

Answer 16

Salts made up of a positive ion and a negative ion.

Question 17

What is a positive stain?

Answer 17

A dye that will be absorbed by the cells or organisms being observed

Question 18

Why is a positive stain preferred?

Answer 18

To add color to objects of interest and make them stand out against the background

Question 19

What is the purpose of staining in microbiology?

Answer 19

To make cells more visible under a microscope

Question 20

What are some commonly used basic dyes?

Answer 20

basic fuchsin, crystal violet, malachite green, methylene blue, safranin

Question 21

How do basic dyes typically serve as stains?

Answer 21

positive stains

Question 22

What is the characteristic of negatively charged chromophores in acidic dyes?

Answer 22

repelled by negatively charged cell walls

Question 23

How do acidic dyes typically serve as stains?

Answer 23

negative stains

Question 24

What are some commonly used acidic dyes?

Answer 24

acid fuchsin, eosin, rose bengal

Question 25

What is simple staining?

Answer 25

Using a single dye to emphasize particular structures in the specimen

Question 26

What is the result of simple staining?

Answer 26

All organisms in a sample appear the same color

Question 27

What is differential staining?

Answer 27

Distinguishing organisms based on their interactions with multiple stains

Question 28

What are some commonly used differential staining techniques in clinical settings?

Answer 28

Gram staining, acid-fast staining, endospore staining, flagella staining, capsule staining

Question 29

What is the purpose of the Gram stain?

Answer 29

Distinguish between bacteria with different types of cell walls

Question 30

What is the purpose of crystal violet in the Gram staining process?

Answer 30

Primary stain

Question 31

What is the role of Gram's iodine in the Gram staining process?

Answer 31

Mordant

Question 32

What is the purpose of the decolourizing agent in the Gram staining process?

Answer 32

Remove excess stain

Question 33

What is the effect of a decolourizing agent on cells with thick peptidoglycan layers?

Answer 33

They generally retain the crystal violet dye and remain purple.

Question 34

What is the effect of a decolourizing agent on cells with thin peptidoglycan layers?

Answer 34

The dye is washed out and they become colourless.

Question 35

What is the purpose of a secondary counterstain?

Answer 35

To stain the decolourized cells pink.

Question 36

What is Gram-staining?

Answer 36

Differential staining technique to distinguish gram-positive and gram-negative bacteria

Question 37

What color are gram-positive cells?

Answer 37

Purple

Question 38

What color are gram-negative cells?

Answer 38

Red/Pink

Question 39

What can Gram staining help clinicians with?

Answer 39

Classify bacterial pathogens into categories associated with specific properties.

Question 40

Which type of bacteria tends to be more resistant to certain antibiotics?

Answer 40

Gram-negative bacteria.

Question 41

What is acid-fast staining?

Answer 41

Differential staining technique

Question 42

What does an acid-fast stain differentiate?

Answer 42

Gram-positive cells with mycolic acids vs. those without

Question 43

What is the primary stain used in acid-fast staining?

Answer 43

Carbol fuchsin

Question 44

What happens to acid-fast cells after the decolorizing agent is applied?

Answer 44

They retain the carbol fuchsin

Question 45

What is the secondary counterstain used in acid-fast staining?

Answer 45

Methylene blue

Question 46

How are non-acid-fast cells stained in acid-fast staining?

Answer 46

They are stained blue with methylene blue

Question 47

What is capsule staining used for?

Answer 47

Determining whether cells in a sample have capsules

Question 48

What are endospores?

Answer 48

Structures that allow certain bacterial cells to survive harsh conditions

Question 49

Can endospores be visualized using Gram staining alone?

Answer 49

No, they appear clear with Gram staining alone

Question 50

What is endospore staining?

Answer 50

Differentiate endospores from the rest of the cell.

Question 51

What is the primary stain used in the Schaeffer-Fulton method of endospore staining?

Answer 51

Malachite green.

Question 52

What stain is used to counterstain the cell in endospore staining?

Answer 52

Safranin.

Question 53

What does endospore staining reveal?

Answer 53

Shape and location of endospores.

Question 54

What are flagella?

Answer 54

Tail-like structures used for locomotion

Question 55

Why can't flagella be seen under a light microscope?

Answer 55

They are too thin.

Question 56

What does the mordant do in flagella staining?

Answer 56

Thickens the flagella

Question 57

What is the staining agent commonly used in flagella staining?

Answer 57

Pararosaniline

Question 58

How are samples prepared for fluorescence and confocal microscopy?

Answer 58

Similarly to samples for light microscopy, but with fluorochromes.

Question 59

What is immunofluorescence?

Answer 59

Dyes attached to an antibody to stain specific proteins on specific types of cells.

Question 60

What is fluorescence in situ hybridization (FISH)?

Answer 60

It stains cells based on whether they have a specific DNA sequence