Lab 3.4: simple stains

Question 1

Bacterial cells are much ?? than eukaryotic cells and come in a variety of ?? and ??

Answer 1

-smaller
-morphologies (shapes)
-arrangements

Question 2

What is the first step in identifying a bacterial species?

Answer 2

-determining cell morphology

Question 3

chromophore:

Answer 3

-portion of the chromogen that gives it its color

Question 4

Basic stains:

Answer 4

-positively charged chromogen
-are attracted to the negative charges on the surface of most bacterial cells (ionic bond), colorizing the cell

Question 5

Common basic stains:

Answer 5

-methylene blue (stain for 30 to 60 seconds)
-crystal violet (stain for 1 minute)
-safranin (stain for 30 to 60 seconds)

Question 6

Basic stains are applied to bacterial smears that have been ??

Answer 6

-heat fixed

Question 7

What does heat fixing do?

Answer 7

-kills the bacteria
-makes bacteria adhere to the slide
-coagulates cytoplasmic proteins to make them more visible

Question 8

What is the purpose of heat-fixing bacterial smears before applying a simple stain?

Answer 8

To improve the adhesion of cells to the slide

Question 9

What role does the chromogen play in a staining solution?

Answer 9

-provide color to the specimen

Question 10

What is the term for the process of fixing cells to a slide before staining?

Answer 10

-heat fixing

Question 11

What is the typical procedure for a simple stain?

Answer 11

-using a single dye to color all cells uniformly

Question 12

What is the primary reason basic stains are attracted to bacterial cells?

Answer 12

-Ionic bond with negative charges on the cell surface

Question 13

Which part of a stain solution is responsible for providing color to the specimen?

Answer 13

-chromogen

Question 14

What component of bacterial cells is commonly stained by a simple stain?

Answer 14

-cell wall

Question 15

Which bacterial structure is not typically visible with a simple stain?

Answer 15

-flagella

Question 16

What is the main advantage of using a simple stain in microbial microscopy?

Answer 16

-It enhances the visibility of cellular morphology

Question 17

Which of the following is a common simple stain used in microbiology?

Answer 17

-crystal violet stain

Question 18

What is the purpose of using a mordant in certain staining procedures?

Answer 18

-fix the dye to the specimen

Question 19

Which of the following is an example of a basic dye used in simple staining?

Answer 19

-methylene blue

Question 20

How do basic stains interact with bacterial cells during the staining process?

Answer 20

-forming ionic bonds

Question 21

What is the primary purpose of a simple stain in microbiology?

Answer 21

-to observe bacterial morphology