Chapter 2

Question 1

T/F - In fluorescence, emitted photons have the same amount of energy as absorbed photons

Answer 1

False

Question 2

Negative staining is the standard approach used to visualize what structure?

Answer 2

Capsules

Question 3

What is iodine used for?

Answer 3

Iodine is a mordant used in gram staining procedure. It “sets” the crystal violet stain within the thick layer of PTG

Question 4

What are the steps in Gram staining?

Answer 4

1. Crystal Violet stain
2. Iodine mordant
3. Ethanol (alcohol) decolorization
4. Safranin counterstain

Question 5

T/F - Preparing a wet mount is involved in prepping a bacterial slide for Gram staining

Answer 5

False

Question 6

Why is it important to fix bacterial smears on a slide?

Answer 6

to attach them to the slide

Question 7

Which type of microscopy would work best for viewing internal cell structures?

Answer 7

Transmission electron microscopy (TEM)

Question 8

Why do we use dyes during microscopy?

Answer 8

it allows for contrast (better visualizaion)

Question 9

T/F - a microscope with a very high magnification and low resolution would allow you to clearly see small structures?

Answer 9

False

Question 10

Gram-___ cells have thicker peptidoglycan layers in their cell walls than gram-____ cells do

Answer 10

positive, negative

Question 11

What is the chemical in some bacterial cell walls that makes it resistant to decolorization after acid-fast staining?

Answer 11

Mycolic acid

Question 12

specific name for a stain that colors the background but not the specimen?

Answer 12

negative stain

Question 13

What term did Robert Hooke use before anyone else?

Answer 13

“cells”

Question 14

What is a basic dye?

Answer 14

stains with positively charged chromophores

Question 15

Explain positive stains

Answer 15

Dyes the specimen but not the background

Question 16

T/F - the difference between a simple microscope and a compound microscope is that the latter only has one lens

Answer 16

False

Question 17

Describe the endospores after using the Schaeffer-Fulton method?

Answer 17

endospores appear green within a pink cell, because only the endospores retain the primary stain

Question 18

What category does gram-staining fall under?

Answer 18

Differential staining

Question 19

Name three types of Special structure stains

Answer 19

1. Capsule stain
2. Endospore stain
3. Flagella stain

Question 20

What color appears with a positive stain?

Answer 20

Ultra violet

Question 21

What color appears with a negative stain?

Answer 21

Pink/red

Question 22

Why do we put oil on the slide?

Answer 22

to prevent refraction

Question 23

What microscope is best used to view virues?

Answer 23

Electron Microscopes

Question 24

What is best visualized with a scanning electron microscope (SEM)?

Answer 24

Surface details

Question 25

What is best visualized with a Transmission Electron microscope (TEM)?

Answer 25

through the cell, inside

Question 26

How do you fix a specimen to a slide?

Answer 26

Either by heat or chemically treating the specimen.

Question 27

What happens during fixation?

Answer 27

microorganisms are killed, movement & metabolism is stopped, integrity of cellular components are preserved

Question 28

what is the name of the colored ion in a dye?

Answer 28

Chromophore

Question 29

what is the name of the uncolored ion in the dye?

Answer 29

counterion

Question 30

what is the stain classified as if the chromophore is positively charged?

Answer 30

Basic dye

Question 31

What is the stain classified as if the chromophore is negatively charged?

Answer 31

Acidic dye

Question 32

What does the cell absorb a positive stain so well?

Answer 32

Cells have negatively charged cell walls, there fore it is attracted to the positive chromophores within the stain.

Question 33

Name the steps in Gram staining

Answer 33

1. Crystal violet 2. Iodine - mordant 3. Alcohol - decolorization 4. Safranin - counterstain

Question 34

How long should the alcohol be used?

Answer 34

10-12 seconds

Question 35

When do you use acid-fast staining?

Answer 35

on cells that do not have PTG

Question 36

What category of staining is acid-fast staining?

Answer 36

differential staining

Question 37

What are the two types of gram-positive cells acid-fast stains are able to differentiate?

Answer 37

cells that have waxy mycolic acids in their cell walls and those that do not

Question 38

are basic dyes or acidic dyes used during a capsule stain?

Answer 38

acidic dyes are used because most capsules do not absorb basic dyes

Question 39

Describe the visual of the capsule stain

Answer 39

the dye stains the background but does not stain the capsule, which appear like halos around the border of the cell