Microscopy and Staining Procedure Flashcards
1
Q
Historically, the science of microbiology has taken its greatest leaps forward as _________ are developed and _____.
A
new tools for the study of microorganisms are developed and old tools are improved
2
Q
The microscope is? (Overview)
A
the microbiologist’s oldest and most basic tool for studying microbial structure.
3
Q
It is the microbiologist’s oldest and most basic tool for studying microbial structure.
A
Microscope
4
Q
Many types of microscopes are used and some are ______ ________.
A
Extremely powerful
5
Q
(Overview) Microorganisms are tiny organism - organism _______________.
A
Cannot be seen by an unaided eye.
6
Q
Generally some type of microscope is required to see them; thus, microorganisms are said to be _____.
A
Microscopic
7
Q
Why are microorganisms said to be microscopic
A
Because generally some type of microscope is REQUIRED to see them
8
Q
It is the technology of making very small things visible to human eye.
A
Microscopy
9
Q
Microscopy is?
A
The technology of making very small things visible to the human eye.
10
Q
In microscopy, the ______ as well as the ______ is expressed in metric system.
A
Size of microorganism, resolving power of optical instrument
11
Q
The _______ (primarily the __ and __) are used to express the sizes of microorganism.
A
Metric units; micrometer; nanometer
12
Q
The metric units are used to?
A
Express the sizes of microorganisms, primarily micrometer and nanometer
13
Q
The basic unit of length in the metric system
A
Meter (m)
14
Q
Meter is equivalent to approximately ___ and is therefore about ____ longer than a ___.
A
39.4 inches; 3.4 inches; yard
15
Q
A meter may be divided into 10 equally spaced units which is called?
A
decimeter (dm)
16
Q
A meter divided into 100 equally spaced units?
A
centimeter (cm)
17
Q
Meter divided into 1000 equally spaced units
A
millimeter (mm)
18
Q
meter divided into 1 million equally spaced units
A
micrometer (um) 10^6
19
Q
a meter divided into 1 billion equally spaced units
A
nanometer (nm) 10^9
20
Q
the sizes of bacteria are expressed in?
A
micrometers
21
Q
whereas the size of viruses are expressed in?
A
nanometers
22
Q
for example, a typical spherical bacterium is approximately?
A
1 um in diameter
23
Q
a typical spherical bacterium is called a?
A
coccus or cocci
24
Q
a coccus or cocci is decribed as?
A
a typical spherical bacterium
25
The smallest virus has the size of?
20 nm
26
20 nm is the size of?
smallest virus
27
Give the metric and English equivalent of the following:
1 meter
standard unit of length; 39.37 inches, 3.38 feet; 1.09 yards
28
Give the metric and English equivalent of the following:
1 dm
0.1 meter or 10^-1 m; 3.9 inches
29
Give the metric and english equivalent of the following:
1 cm
0.01 = 10^-2 m; 0.39 inch
30
Give the metric and English equivalent of the following:
1 mm
0.0001 = 10^-3 m; .039 inch = 3.9 x 10^-2
31
Give the metric and English equivalent of the following:
1 micrometer
10 ^-6 meter; 3.9 x 10^-5 in
32
Give the metric and English equivalent of the following:
1 nanometer
10^-9 m ; 3.9 x 10^-8 in
33
Give the metric and English equivalent of the following:
1 angstrom (A)
10^-10 m; 3.9 x 10^-9 in
34
The existence of microorganisms was ___ until the invention of the microscope
unknown
35
Is an optical instrument that is used to observe tiny objects, often objects cannot be seen at all times with the unaided human eye.
Microscope
36
Microscope definition in The Microscope section
optical instrument used to observe tiny objects cannot be seen by unaided eye.
37
In seeing microorganisms, a microscope of some sort is needed and it can be either ____ or ____.
a light microscope or an electron microscope
38
In general, these microscopes are used to examine cells at relatively low magnifications
light microscopes
39
In general, these microscopes are used to examine cells and cell structure at very high magnifications
electron microscopes
40
what is the difference between a light microscope and an electron microscope
light - relatively low magnifications ; electron - very high magnifications
41
In the microbiology laboratory, the sizes of cellular microbes are measured using an ____.
ocular micrometer
42
an ocular micrometer is defined as
a tiny ruler within the eyepiece (ocular) of the compound light microscope.
43
It is used to measure the dimensions of objects being viewed with a compound light microscope.
ocular micrometer
44
an ocular micrometer is used as ...
used to measure the dimensions of objects being viewed with a compound light microscope.
45
number of time that microscope enlarge the original size of the object is
magnification power of the microscope
46
what is magnification power?
the number of time that microscope enlarge the original size of the object
47
the limit in each optical instrument of what can be seen in using the instrument
resolution power or resolving power
48
Resolution power is defined as...
the ability of the lenses to distinguish fine details and structure
49
What is the specific definition of resolution power
Specifically, it is the ability of the lenses to distinguish between two points, a specified distance apart.
50
It is the ability of the lenses to distinguish between two points, a specified distance apart.
Resolution power
51
the ability of the lenses to distinguish fine details and structure
resolving power
52
A microscope with a resolving power of 0.4 nm can distinguish?
between two points if they are at least 0.4 nanometer apart.
53
Who developed the simple microscope and at what time?
Anton van Leeuwenhoek; 16th century
54
The simple microscope has only one lens and is similar to?
a magnifying glass
55
Anton van Leeuwenhoek was considered to the best what?
best lens grinder in the world in his day
56
Leeuwenhoeks lenses were grounded with such precision that a single lens could magnify a microbe at?
300 x its original size
57
a microscope that contains more than one magnifying lense
compound microscope
58
a compound microscope is defined to be
a microscope that contains more than one magnifying lense
59
The first compound microscope was developed by ... and when?
Hans Jansen and his son Zaccharias Jansen in the late 16th century
60
What was the issue with the first compound microscope?
The microscope was of poor quality and could not be used to observe live bacteria.
61
At what time did a significantly better microscope was developed and who developed it?
1830; Joseph Jackson Lister (father of Joseph Lister)
62
A compound microscope has usually a magnification of ... and has a resolving power of ...
magnify objects about 1000 times; 0.2 um
63
0.2 um resolving power is about ...
1000 times better than the resolving power of the unaided eye
64
what is the source of illumination in compound microscope?
visible light
65
visible light is the ... of compound microscope?
source of illumination
66
Because it uses visible light, compound microscope is also referred as?
compound light microscope
67
what limits the size of the object that can be seen in compound light microscope?
wavelength of the visible light
68
THe compound light microscope contains two magnifying lens systems. These are?
Ocular lens found in eyepiece and the other found in the objective
69
The ocular lens is found within? and usually has a magnifying power of?
eyepiece or ocular; x10
70
the second magnifying lens is found in ------ which is positioned immediately ____ the ____ to be _______
objective; immediately above the object to be viewed
71
Each objective lens system has its own what?
magnification power
72
If the LPO and HPO of the microscope is ____, the image remains in approximate focus when objective is shift from LPO to HPO.
parfocal
73
When the LPO and HPO of a microscope is parfocal, the image remains in?
approximate focus when objective is shift from LPO to HPO
74
The product of the magnification power of its objective and ocular lenses
total magnification
75
what is total magnification?
The product of the magnification power of its objective and ocular lenses
76
How do you calculate the total magnification of the microscope?
multiplying the magnifying power of the ocular lens (x10) and the magnifying power of the objective being used
77
So a specimen is usually first observed using what part of a microscope?
a low power objective with a magnification of x10
78
Once the specimen is in focus after it was subjected in low power objective, the _____ is then swung into position.
high power or high dry objective
79
The high powr objective can be used to study what microorganisms?
algae, protozoa and other large microorganisms.
80
in bacteriological examination, what kind of objective should be used?
oil-immersion objective
81
oil-immersion objective is used in?
bacteriological examination
82
How do you prepare an oil-immersion objective?
a drop of immersion oil is placed between the specimen and the objective
83
it reduces the scattering of light and ensures that the light will enter the oil-immersion lens
immersion oil
84
This is made up of a series of lenses and utilizes TRANSMITTED visible light as its source of illumination.
brightfield microscope
85
In brightfield microscope objects are observed against ______
a bright background
86
A bright background or transmitted light is used to visualized the _____ of ____ and ____ .
morphology of bacteria and fungi
87
The morphology of bacteria and fungi is visualized in what states?
in living (unstained) or nonliving (stained) state
88
The brightfield microscope cannot be used to observe organism measures as ?
less than 0.2 micrometer in diameter of thickness
89
Examples of such organisms that a brightfield microscope cannot observe are:
spirochetes and virus
90
this microscope utilizes reflected light instead of transmitted light.
darkfield microscope
91
The reflected light used in darkfield microscope goes through a ____ with an _____ that blocks the light such that only the object is illuminated.
special condenser; opaque disc
92
So the dark field microscope observes an object that appears to be bright under a _____
dark background
93
The darkfield microscope are used to observe miroorganisms that are _____ under ordinary light microscope.
invisible
94
dark field microscope is routinely used to view spirochetes such as ____ which cauase what disease?
treponema pallidum; causative agent of syphilis
95
microscope that has a special condenser and objective lenses that accentuate small difference in the refractive index of various structures within theorganism.
phase-contrast microscope
96
In a phase-contrast microscope, what is the use of the special condenser and objective lenses?
to accentuate small difference in the refractive index of various structures within the organism.
97
What happens to the light passing through the object of different refractive indexis?
the light is slowed down and diffracted
98
the change in the speed of light in a phase-contrast microscope is seen as what?
different degrees of brightness
99
what causes the different degrees of brightness in a phase-contrast microscope?
the changes in the speed of light
100
phase-contrast microscopes can be used to observe what type of living microorganisms?
unstained living microorganisms
101
Why is it possible for unstained living microorganisms to be studied under a phase contrast microscope?
Because the light refracted by living cells are different from the light of the refracted medium thus the contrast is increased and the organisms are more easily seen.
102
what internal structure example is examined by the phae-contrast microscope?
endospores
103
why is phase contrast especially useful in examining LIVING microorganisms?
because it permits the examination of internal structures
104
It is also not necessary to fix (attach the specimen to the slide) or stain the specimen because it remains living disallowing the possibility of?
distortion or kill the microorganism
105
what procedures are not necessary in using a phase-contrast microscope with a living microorganism?
fixing (attaching the specimen in a slide) and staining the specimen
106
what is phase contrast microscope's resolving power and useful magnification?
0.2000 um and 1000x
107
this microscope uses ultraviolet light and flourescent dye
fluorescence microscope
108
what do you call fluorescent dyes?
fluorochromes
109
What happens to the object under study in a fluorescence microscope?
Fluoresces against the dark background
110
Fluorescence microscopy is often used in what laboratories?
Immunology laboratories
111
What does fluorescence microscopy's role in immunology laboratories?
Detection of specific antigen and antibodies
112
What microscope uses an electron beam as a source of illumination and electromagnet to focus the beam?
Electron Microscope
113
In electron microscope what is used as source of illumination?
Electron beam
114
In electron microscope what is used to focus the electron beam?
Electromagnet
115
Electron microscope can magnify an object at ______
10,000x or more
116
Objects smaller than ____ must be examined with an electron microscope
0.2 um
117
Objects smaller than 0.2 um that should be examined by an electron microscope includes examples like?
Viruses and internal structure of cells
118
What are the two types of electron microscope?
Transmission electron microscope
Scanning electron microscope
119
This type of microscope uses electromagnetic lenses instead of glass lenses that is used in a light microscope.
Transmission electron microscope
120
What lenses is used in a transmission electron microscope, what's the difference in light microscope?
Transmission - electromagnetic
Light - glass
121
What are the three things an electromagnetic lens controls?
Illumination, focus, magnification
122
This microscope is used to study the molecular and atomic shape of organism.
Transmission electron microscope
123
Transmission electron microscope is used to study the _____ and _____ of organism
Molecular and atomic shape of organism
124
A transmission electron microscope can also determine the _______ inside the cell as well as its ________.
Temperature; chemical properties
125
This microscope is used to examine internal structure of viruses in thin section of cells
Transmission electron microscope
126
Transmission electron microscope is used to examine internal structure of viruses in what?
Thin section of cells.
127
How much is the resolving power and magnification power of a transmission electron microscope
2.5 nm; 10,000-100,000x its original size
128
This microscope provides three dimensional views of the specimen.
Scanning electron microscope
129
Scanning electron microscope is provides ______ view of the specimen.
Three-dimensional
130
Microscope used to examine SURFACE features of cells and viruses.
Scanning electron microscope
131
What does a scanning electron microscope examines in cells and viruses
Surface features
132
What is the resolution and magnification power of a scanning electron microscope
20 nm and 1,000-10,000x its original size
133
What is the difference in terms of use and components of the 5 types of compound microscope?
Answer in module
134
What is the difference between the two types of electron microscope
Answer in module
135
What is the difference between the simple and compound microscope?
136
What is the difference between light and electron microscope
Answer in module
137
What is the commonly used microscope in microbiology laboratory?
Compound light microscope
138
What do you call a compound microscope with single eyepiece (ocular)
Monocular
139
A compound microscope with two eyepieces
Binocular
140
What is the difference between monocular and binocular?
Monocular - single eyepiece or ocular
Binocular - two
141
Where does light enters in a compound microscope?
From the source in the base
142
As light enters the microscope it often passes through a what?
Blue filter
143
What does the blue filter do to the light passing through it?
It filters out the long wavelength of the light, leaving the shorter wavelengths
144
As the blue filters the long wavelength of light what in turn happens?
Shorter wavelengths are left thus improving resolution
145
How many does a compound light microscope have up to in terms of lenses?
Up to 5 lenses with different magnification powers.
146
What are the four objectives used in most compound light microscope?
x4, x10, x40, x100 objectives
147
As mentioned above to get the total magnification, it is calculated by multiplying the magnifying power of the _____(_) by the magnifying power of the ______
Ocular (x10) ; objective you are using
148
What objective is rarely used in microbiology?
x4
149
Usually specimens are first observed using the ____ objective
x10
150
Once the specimen is in focus the _____ objective is then swung into position
High power or high dry
151
This swung high power or high dry objective is used to observe ___, ____, and _____.
Algae, protozoa, and other large microorganisms
152
Oil-immersion objective has a total magnification of?
x1000
153
Why should an oil immersion objective be used to study bacteria?
Because they are so tiny
154
What does the immersion oil do to the microscope?
It reduces the scattering of light and ensure that the light will enter the oil immersion lens
155
The oil immersion objective cannot be used without ?
Immersion oil
156
This oil is not required in _____
Other objectives
157
controls the amount of light entering through the condenser
collector lens with field diaphragm
158
used to move the stage and microscope slide
stage adjustment knobs
159
contains a lens system that focuses light onto the specimen
condenser
160
used to adjust the amount of light passing through the condenser
iris diaphragm control arm
161
used to adjust the height of the condenser
condenser control knob
162
turns the light source on and off
on/off switch
163
controls the amount of light emitted from the light source
rheostat control knob
164
used to adjust the amount of light passing through the collector lens
field diaphragm lever
165
supports the binocular body and the revolving nosepiece
arm
166
used to focus the objective lenses
fine and coarse adjustment knobs
167
contains the light source
base
168
held with one hand when carrying the microscope, with the other hand beneath the base to support the weight of the microscope
arm
169
used to magnify objects placed on the stage
objective lenses
170
flat surface on which the specimen is placed
stage
171
holds the ocular lenses in their proper place
binocular body
172
holds the objective lenses
revolving nosepiece
173
is a x10 magnifying lens
ocular lens
174
LOCATION: front side of the base
rheostat control knob
175
LOCATION: on the side of the base
on/off switch
176
LOCATION: at the top of the microscope
ocular lens
177
LOCATION: on the condenser
iris diaphragm control arm
178
LOCATION: on the arm of the microscope near the base
fine and coarse adjustment knobs
179
LOCATION: beneath the stage
condenser; stage adjustment knobs
180
LOCATION: attached to the field diaphragm
field diaphragm lever
181
LOCATION: beneath and behind the condenser
condenser control knob
182
LOCATION: above the stage
revolving nose piece
183
LOCATION: beneath the condenser
collector lens with field diaphragm
184
LOCATION: held in place above the stage by the revolving nosepiece
objective lenses
185
LOCATION: directly beneath the objective lenses and the revolving nosepiece
stage
186
What can be used to stain cells and increase the contrast so that they can be more easily seen in the brightfield microscope?
dyes
187
Dyes are used to stain cells and increase the contrast so that they can be more easily seen in the what microscope?
brightfield microscope
188
Dyes are ____ compounds and has an affinity for specific ______.
organic; cellular materials
189
Since in microbiology many dyes used are positively charged thus they are called?
basic dyes
190
examples of basic dyes (3)
methylene blue, crystal violet, safranin
191
So basic dyes bind strongly with negatively charged cell components such as?
nucleic acids, and acidic polysaccharides
192
cells also have surfaces that tends to be negatively charged therefore basic dyes have a high affinity to the surface of the cell making them very useful ____.
general-purpose stains
193
Describe a bacteria in its living state
colorless, transparent, and difficult to see under the microscope.
194
To make bacteria visible under the microscope a method has been devised that enables scientists to examine bacteria.
staining method
195
the process by which the organic dye is applied to the smeared organism for them to become visible under the microscope
staining
196
staining is the process by which the______ is applied to the ______ for them to become visible under the microscope
organic dye, smeared organism
197
In preparation for staining, the bacteria are smeared unto a _____, _____ and then ____.
glass slide, air-dried, fixed
198
a thin film of material containing microorganisms spread on the surface of the glass slide
smear
199
THe process that proceeds after the smear has been prepared where the specimen has to be attached or secured in a slide.
fixation
200
what is the process of fixation?
the process of attaching or securing the smear in a slide
201
two common method of fixation:
heating fixation and methanol fixation
202
is usually accomplished by passing the smear through a bunsen burner flame
heat fixation
203
If heat fixation is not properly done, ____ can distort the _____.
excess heat; morphology of the cell
204
how is heat fixation accomplished?
by passing the smear through the bunsen burner flame
205
this method is accomplished by flooding the smear with absolute methanol for 30 seconds.
methanol fixation
206
this method is accomplished by flooding the smear with absolute methanol for 30 seconds.
methanol fixation
207
how is methanol fixation accomplished? BY?
flooding the smear with absolute methanol for 30 sec
208
what are the three purposes of the fixation method
1. it kills the organism
2. It preserves the morphology of the organism
3. it anchors the smear to the slide
209
is the application of dye or stain to microbial smears for them to become visible under the microscope.
staining
210
the purpose of staining is to increase the contrast between microorganisms and the background so that they are more readily seen in the ______.
light microscope
211
This type of staining is used to observe or determine the bacterial shape and morphologic shape.
Simple staining
212
the simple staining utilizes how many dyes?
single dye
213
the single dye used in simple staining can either be?
water or alcohol based
214
what are the commonly used stains for simple staining are?
crystal violet and methylene blue
215
simple staining procedure is commonly used to observe?
bacterial capsule, spores, flagella
216
simple staining procedure that is commonly used to observe bacterial capsule, spores, and flagella are collectively known as?
structural staining procedure
217
The six steps of simple staining procedure
Smear loopful of microbes onto slide
Air dry
Drip methanol onto specimen to fix
Flood with methylene blue
Rinse with water and blot dry
Examine under oil immersion objective
218
this staining procedure is most frequently used to differentiate Gram-staining bacteria and Acid-fast bacteria.
Differential Stain
219
Differential staining is used commonly to differentiate between a ______- bacteria and _______.
Gram-staining bacteria and acid fast bacteria
220
The Gram-stain and Gram-staining procedure was developed in ___ and by the ______.
1884, Danish bacteriologist Dr. Hans Christian Gram
221
Gram staining is one of the most useful staining procedures because it classifies into two large groups: ____ and _____.
Gram-positive and Gram-negative bacteria
222
State the gram staining procedure's four steps
223
The color of the bacteria at the end of the gram staining procedure depends upon the _____?
chemical composition of their cell wall
224
What is the color of a gram-positive bacteria?
blue-to-purple in color
225
the thick layer of _____ in the cell wall of Gram-positive bacteria makes it difficult to remove the crystal violet-iodine complex during decolorization.
peptidoglycan
226
the thick layer of peptidoglycan in the cell wall of Gram-positive bacteria makes it difficult to remove the ____.
crystal violet-iodine complex during decolorization.
227
Gram-negative bacteria is in what color at the end of the procedure?
pink-to-red in color
228
during the gram-staining procedure in a gram-negative bacteria, the _____ was removed from the cells during the _____, and the cell was subsequently stained by the final stain ______.
crystal violet; decolorization; safranin
229
What's the difference between the layer of peptidoglycan in a gram-positive or -negative bacteria?
thick layer -positive
thin layer -negative
230
The ____ layer of ____ makes it easier to remove the ____ during decolorization
thin; peptidoglycan; crystal violet-iodine complex
231
a stain that binds strongly only to bacteria that have a waxy material in their cell.
Acid-fast stain
232
The technique of acid-fast staining is used to identify all bacteria in the genus ____, including the two most important pathogens which are? and what disease they cause.
mycobacterium; mycobacterium tuberculosis, the causative agent of tuberculosis and Mycobacterium leprae, the causative agent of leprosy
233
acid-fast stain was developed in ___ by ____.
1882; Paul Ehrlich
234
acid-fast stain is especially useful in tuberculosis laboratory where the acid fast mycobacterium are readily seen as ____ against a ____ background in _____ from a tuberculosis patient.
red bacilli; blue or green background; sputum specimen
235
The two methods of acid-fast staining:
Ziehl-Neelsen stain
Kinyoun stain
236
Ziehl_Neelsen stain is also known as the "___" because it requires steam-bathing the organism with the aqueous dye
hot method
237
Ziehl_Neelsen stain is also known as the "hot method" because it requires ____ the organism with the ____.
steam bathing; aqueous dye
238
Kinyoun stain is also known as "____" because it does not utilize heat for staining
cold method
239
what decolorizing agent is used in acid-fast stain?
mixture of acid and alcohol
240
what red dye is used in the acid fast staining method?
carbol fuchsin
241
the red dye ____ is first driven from the bacterial cell wall with ____ so that the decolorizing agent does not remove the red color from the mycobacterium cell wall.
carbol fuchsin; heat
242
the heat is necessary because the cell wall of the mycobacterium contains ___, which prevents the stain from ____.
waxes: penetrating the cell
243
the heat is necessary because the cell wall of the mycobacterium contains ___, which prevents the stain from ____.
waxes: penetrating the cell
244
what does the heat do to the waxes so that the stain can penetrate?
the heat softens the waxes
245
bacterias that retain the red color particularly mycobacterium's after it is decolorized by a mixture of acid and alcohol then it is said to be?
acid-fast
246
most bacteria that are decolorized by the acid-alcohol treatment are sai to be?
non-acid fast
247
These type of staining method are used to demonstrate specific structure in a bacterial cell.
Special stain
248
Metachromatic granules can be visualized using the?
Loeffler alkaline methylene blue stain (LAMBS)
249
Stain for demonstration of bacterial capsule or slime layer
Hiss stain
250
Stain for demonstrating bacterial endospores
Schaeffer-Fulton endospore stain
251
Stain that add layers of dye or metal to the surface of the flagella to make those surfaces visible.
Flagellar stains
252
What is visualized using the Loeffler alkaline methylene blue stain?
Metachromatic granules
253
What is demonstrated using Hiss stain?
Bacterial capsule/slime layer
254
What is demonstrated using Schaeffer-Fulton stain?
Bacterial endospores
255
Flagellar stains add layers of dye or metal to the surface of the _______ to make those surfaces visible.
Flagella
256
Flagellar stains add layers of ________ to the surface of the flagella to make those surfaces visible.
Dye or metal
257
Flagellar stains add layers of dye or metal to the ______ of the flagella to make those ______.
Surfaces; surfaces visible
258
This solution is an aqueous solution used for staining bacteria, fungi, and blood parasite in blood smear
Loeffler alkaline methylene blue solution
259
Using the solution in an oil immersion objective, the bacterial cell stain is ______ color and the background stain _______.
Medium blue, lighter blue
260
A type of stain that stains the capsule or slime layer and the bacterial cell with a lighter background
Hiss stain
261
With hiss stain the capsule appears as a ______ color between a _____ bacterial cell and _____ background
Light violet, dark violet colored, colorless
262
The Schaeffer-Fulton endospore stain is designed to isolate endospores by staining endospore _____ and any other bacterial bodies ____.
Green, red
263
The primary stain in Schaeffer-Fulton endospore stain is _______.
Malachite green
264
The counterstain in Schaeffer-Fulton endospore stain is?
Safranin
265
The counterstain dyes any other bacterial bodies?
Red
266
The ____ allows observation of bacterial flagella under the light microscope.
Flagellar stain
267
_____ are normally too thin to be seen in conditions with the flagellar stain.
Bacterial flagella
268
The flagellar stain employs a _____ to coat the flagella with stain until they are thick enough to be seen under the microscope.
Mordant
