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MICROBIOLOGY!225-80 > Chap 3 > Flashcards

Chap 3 Flashcards

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1
Q

What is the function of the diaphragm on a compound microscope?

A

Controls the amount of light entering the condenser

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2
Q

The ocular lens is used to

A

to remagnify the image formed by the objective lens.

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3
Q

The measure of the light-bending ability of a medium is the

A

refractive index

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4
Q

MOST ocular lenses magnify specimens by a factor of

A

10x

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5
Q

The ability of the lenses of a microscope to distinguish fine detail and structure is called

A

resolution

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6
Q

Which microscope uses an opaque disk to block light that would enter the objective lens directly?

A

Darkfield microscope

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7
Q

Which microscope uses an ultraviolet light source?

A

Fluorescence microscope

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8
Q

Which microscope illuminates specimens with blue light and produces three-dimensional images?

A

Confocal microscope

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9
Q

Which microscope forms an image from two sets of light rays, one from the light source and the other diffracted from a structure in the specimen?

A

Phase-contrast microscope

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10
Q

What microscope uses a metal-and-diamond probe to produce a three-dimensional image?

A

Atomic force microscope

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11
Q

Which microscope is especially useful in studying the surface structures of intact cells and viruses?

A

Scanning electron microscope

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12
Q

In transmission electron microscopy, the specimen is placed on a

A

copper mesh grid.
glass slide.
plastic slide.
magnesium mesh grid

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13
Q

Which microscope is extremely valuable for examining different layers of specimens and often involves the use of shadow casting?

A

Transmission electron microscope

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14
Q

With a scanning electron microscope, objects are generally magnified

A

1,000 to 500,000x

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15
Q

With a transmission electron microscope, objects are generally magnified

A

10,000 to 10,000,000x

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16
Q

Before microorganisms are stained, MOST appear ________ when viewed with brightfield microscopy

A

colorless

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17
Q

The chromophore of basic dyes is a ________ and is ________ to MOST types of bacteria.

A

cation; attracted

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18
Q

Which one of the following is NOT a kind of staining technique?

A

selective

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19
Q

The process of fixing a slide attaches the microorganisms while simultaneously

A

killing the organisms

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20
Q

A technique used for preparing a slide with colorless bacteria against a colored background is called

A

negative staining.

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21
Q

What is the mordant in the Gram stain?

A

Iodine

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22
Q

Flagella are stained with

A

carbolfuchsin

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23
Q

Capsules are stained using a(n)

A

negative stain

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24
Q

Endospores are stained using a(n)

A

Schaeffer-Fulton stain

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25
Q

What color are gram-negative bacteria at the completion of the Gram staining process?

A

Pink

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26
Q

The appearance of Mycobacterium leprae after they are stained with an acid-fast stain is

A

Red

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27
Q

Microorganisms are measured in

A

micrometers & and nanometers (nm)

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28
Q

How many nanometers is 10 micrometers?

A

10000 nm

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29
Q

A simple microscope has only one

A

lens

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30
Q

A microscope is similar to a magnifying glass, but with a much better

A

(higher magnification) lens

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31
Q

Any kind of microscope that uses visible light to observe specimens

A

Light Microscopy

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32
Q

In a _________ __________ the image from the objective lens is magnified again by the ocular lens

A

compound microscope

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33
Q

In a compound microscope, the image from the objective lens is magnified again by the

A

ocular lens

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34
Q

Total magnification

A

objective lens x ocular lens

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35
Q

Resolution

A

is the ability of the lenses to distinguish two points

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36
Q

A microscope with a resolving power of 0.4 n m can distinguish between two points at least . n m apart

A

0.4

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37
Q

________ wavelengths of light provide greater resolution

A

Shorter

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38
Q

refractive index

A

is a measure of the light-bending ability of a medium

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39
Q

Light may refract after passing through a specimen to an extent that it does not

A

pass through the objective lens

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40
Q

Immersion oil is used to

A

keep light from refracting

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41
Q

Brightfield illumination

A
  1. Dark objects are visible against a bright background
  2. Light reflected off the specimen does not enter the objective lens
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42
Q

Dark objects are visible against a bright background
Light reflected off the specimen does not enter the objective lens

A

Brightfield illumination

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43
Q

Light microscopes are useful for studying specimens ranging in size from about _mm to ___nm

A

1mm to 200 nm

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44
Q

Shortest wavelength of visible light

A

390 nm

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45
Q

most common form of light microscopy is called

A

brightfield microscopy

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46
Q

Shortest wavelength of light is

A

390 nm

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47
Q

What happens during brightfield microscopy?

A

the light beam passes through the sample and into the objective lens

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48
Q

lamp

A

Where the light beam is initiated

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49
Q

light lamp is divergent

A

Light spreads out at it approaches the condenser lens

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50
Q

Condenser lens

A

gathers the beam of light and focuses it so that it converges on the specimen with high intensity in a small area.

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51
Q

Specimen

A

Usually on a glass slide that rests on a platform called the stage

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52
Q

What happens when the light beam hits the sample

A

The light rays are reflected and refracted or absorbed by the sample

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53
Q

after the beam leaves the specimen, it passes through the

A

objective lens

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54
Q

objective lens

A

performs the bulk of the magnification of the specimen

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55
Q

eyepiece

A

receives the light beam from the objective lens and refocuses it to recreate the image in the viewer’s eye

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56
Q

ocular lenses

A

Lenses found within the eyepiece

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57
Q

Through what lenses does light pass in a compound microscope?

A

objective and ocular

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58
Q

What does it mean when a microscope has a resolution of 0.2 nanometer?

A

Two points can be distinguished if they are at least 0.2 nm apart.

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59
Q

Explain how electron microscopy differs from light microscopy.

A

The electron microscope uses electrons as the source of illumination instead of light. The beam has a short wavelength. The focusing element is electromagnets. It’s resolving power is 2nm instead of the light microscope’s 0.2um. It is used a lot for viruses and internal cell structures.

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60
Q

Light objects are visible against a dark background

A

Darkfield microscopy

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61
Q

Opaque disk placed in condenser

A

Darkfield microscopy

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62
Q

Only light reflected off the specimen enters the objective lens

A

Darkfield microscopy

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63
Q

Allows examination of living organisms and internal cell structures

A

Phase-contrast microscopy

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64
Q

Allows examination of living organisms and internal cell structures

A

Phase-Contrast Microscopy

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65
Q

How does phase-contrast microscopy work?

A

Brings together two sets of light rays, direct rays, and diffracted rays to form an image

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66
Q

Similar to phase-contrast
Differential Interference Contrast (D I C) Microscopy

A

Uses two light beams and prisms to split light beams, giving more contrast and color to the specimen

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67
Q

How does DIC microscopy work?

A

Uses two light beams and prisms to split light beams, giving more contrast and color to the specimen

68
Q

How does fluorescence microscopy work?

A
  1. Uses U V (short wavelength) light
    2.Fluorescent substances absorb U V light and emit longer wavelength (visible) light
    3.Cells may be stained with fluorescent dyes (fluorochromes) if they do not naturally fluoresce
69
Q

In confocal microscopy, cells are stained with

A

fluorochrome dyes

70
Q

In confocal microscopy, short blue light is used to

A

excite a single plane of a specimen

71
Q

In confocal microscopy, each plane of specimen is illuminated and

A

a three-dimensional image is constructed with a computer

72
Q

Confocal microscopy can examine layers of cells to a depth of

A

100 micrometes

73
Q

In Two-Photon Microscopy, cells are stained with

A

with fluorochrome dyes

74
Q

In two-photon microscopy, Two photons of long-wavelength (red) light are used to

A

excite the dyes

75
Q

Two-photon microscopy can study living cells up to

A

1mm deep

76
Q

Super-Resolution Light Microscopy uses how many laser beams?

A

Uses two laser beams

77
Q

Functions of the two laser beams in Super-Resolution Light Microscopy

A
  1. One wavelength stimulates fluorescent molecules to glow
    2.Second wavelength cancels out all fluorescence except for that in one n m
78
Q

In Super-Resolution Light Microscopy A computer scans the specimen nm by nm, then

A

puts the images together

79
Q

Scanning Acoustic Microscopy measures

A

Measures sound waves that are reflected back from a specimen

80
Q

Scanning Acoustic Microscopy is used to

A

Used to study cells attached to surfaces

81
Q

resolution of Scanning Acoustic Microscopy

A

1 micrometer

82
Q

How are brightfield, darkfield, phase-contrast, and fluorescence microscopy similar?

A

They all need a light source

83
Q

Uses electrons instead of light

A

Electron microscopy

84
Q

In electron microscopy, The shorter wavelength of electrons gives greater

A

resolution

85
Q

When is electron microscopy used?

A

Used for images too small to be seen with light microscopes, such as viruses

86
Q

How does Transmission Electron Microscopy work?

A

A beam of electrons passes through ultrathin sections of a specimen, then through an electromagnetic lens, then focused on a projector lens

87
Q

in transmission electron microscopy specimens may be stained with

A

heavy-metal salts for contrast

88
Q

Transmission Electron Microscopy magnification power

A

10,000 to 10,000,000 x; resolution of 10 p m

89
Q

How does Scanning Electron Microscopy work?

A

An electron gun produces a beam of electrons that scans the surface of an entire specimen

90
Q

In scanning electron microscopy, secondary electrons emitted from the specimen

A

produce a three-dimensional image

91
Q

Magnification of Scanning electron microscopy

A

Magnifies objects 1,000 to 500,000 x;

92
Q

Resolution of Scanning electron microscopy

A

10 nm

93
Q

Use electrons to probe a sample

A

Electron microscope

94
Q

Electron microscopes are useful for studying samples in the size range of

A

10 nm to 100 micrometer range

95
Q

can see specimens are small as ribosomes and as large as RCS

A

electron microscope

96
Q

Are used to produce two-dimensional images of internal structures of cells

A

transmission electron microscope

97
Q

Produces three dimensional images of the surfaces of specimens

A

scanning electron microscopes

98
Q

What can be used to stain specimens for electron microscopy?

A

Electron-dense compounds such as heavy metal salts

99
Q

Electron gun

A

initiates a beam of electrons .

100
Q

The electron gun beam is divergent, meaning that

A

it spreads out as it approaches the condenser lens

101
Q

condenser lens of transmission electron microscope

A

gathers the beam of electrons and focuses it so that it converges on the specimen with high intensity in a small area

102
Q

has electromagnetic lens

A

condenser in electron microscope

103
Q

In transmission electron microscope the specimen is

A

a tiny slice of cells that rests on an equally tiny copper grid

104
Q

In transmission electron microscopy, what happens when the electrons interact with the sample

A

they are either reflected and refracted, or absorbed by the sample.

105
Q

In transmission electron microscopy, after hitting the specimen

A

the beam continues to diverge downward on its path away from the specimen and into the objective lens

106
Q

Performs the bulk of magnification of the specimen

A

objective lens

107
Q

Projector lens in transmission electron microscope

A

receives the electron beam from the objective lens and refocuses it to recreate the image that the viewer sees in the fluorescent screen

108
Q

what captures the image in the transmission electron microscope

A

internal camera

109
Q

similarities between a light microscope and a transmission electron microscope

A
  • both have a source of light or electrons

-both have a condenser lens to focus the source

-both have an objective lens to refocus the image

110
Q

differences between a light microscope and a transmission electron microscope

A
  • ## the path of light is from bottom to top in the light microscope and opposite in the electron microscope
111
Q

Ability to distinguish between objects that are close together

A

resolution

112
Q

Resolution depends on the

A

wavelength of the source

113
Q

smaller wavelength lead to

A

higher resolution

114
Q

average wavelength of white light is

A

550 nm

115
Q

wavelength of electron is

A

.1 nm

116
Q

Why do electron microscopes have greater resolution than light microscopes?

A

because electrons have a shorter wavelength than light

117
Q

Explain how Scanning Tunneling Microscopy works

A

Uses a tungsten probe to scan a specimen and reveal details of its surface

118
Q

Resolution of scanning tunneling microscopy

A

1/100 of an atom

119
Q

How does Atomic Force Microscopy work?

A

Uses a metal-and-diamond probe placed onto a specimen; movements are recorded

120
Q

Atomic force microscopy produces

A

three-dimensional images at near atomic detail

121
Q

For what is T E Meter used? S E Meter ? Scanned-probe microscopy?

A

TEM: the electrons pass through a thin section of the specimen
SEM: the electrons strike the surface of the specimen, secondary electrons leaving the surface are viewed on a screen.
Scanned Probe (SPM): family of tools used to make images of nanoscale surfaces and structures, including atoms.

122
Q

Differentiate an acidic dye from a basic dye.

A

Acidic: negative ion (anion)
Basic: positive ion (cation)

123
Q

Explain the purpose of simple staining

A

used to determine cell shape, size, and arrangement of microorganisms found in soil and water.

124
Q

List Gram stain steps, and describe the appearance of gram-positive and gram-negative cells after each step

A

primary stain, mordant, decolorizer, counterstain

125
Q

Compare and contrast the Gram stain and the acid-fast stain.

A

Gram Stain: Differential staining
G+ purple- staph, strep
G- red
Primary- crystal violet
Mordand- Iodine
Decolorizer- alcohol +purple -colorless
Counterstain- safranin (-) red

Acid Fast: TB, leprosy (hansens)
AF+ Red
AF- Blue
TB- waxy cell wall- mycelia acid
=if add primary stain and heat, melts wax. Cool wax- hardens
Primary- carbolfuchsin (red) (heat)
Decolorizer- AF-, colorless
Secondary- AF-, Blue
(if AF+, deep red instead)
Counterstain- Methylene Blue

126
Q

Explain why each of the following is used: capsule stain, endospore stain, flagella stain`

A

Capsule: both the cell and background are stained. (negative stain)
Endospore: heat is required to drive a malachite green stain into endospores.
Flagella: requires a mordant to make the flagella wide enough to see.

127
Q

Staining

A

coloring microorganisms with a dye that emphasizes certain structures

128
Q

smear

A

a thin film of a material containing microorganisms spread over a slide

129
Q

what does fixing do to microorganisms

A

Microorganisms are fixed (attached) to the slide, which kills the microorganisms

130
Q

Live and/or unstained specimens have little contrast with the surrounding medium. Live specimens are used to

A

study cell behavior

131
Q

very useful tools to study specimens smaller than about 1mm

A

microscopes

132
Q

both light and electron microscopes use stains to

A

increase the contrast and visibility of the specimen under study and aid in classification

133
Q

stains consist of

A

a positive and negative ion, one of which is colored (chromophore)

134
Q

in a basic dye, the chromophore is a

A

cation

135
Q

in an acidic dye

A

the chromophore is an anion

136
Q

negative staining

A

Staining the background instead of the cell is called

137
Q

simple staining

A

use of a single basic dye

138
Q

Purpose of simple stains

A

Highlights the entire microorganism to visualize cell shapes and structures

139
Q

Mordant purposes

A

may be used to hold the stain or coat the specimen to enlarge it

140
Q

Why doesn’t a negative stain color a cell?

A

it stains the background instead of the cell

141
Q

Why is fixing necessary for most staining procedures?

A

its purpose is to bind the specimen to the slide so that it does not wash off during staining. Killing the cells with heat fixation also increases their permeability to the dyes used in staining.

142
Q

purpose of differential stains?

A

Used to distinguish between bacteria

143
Q

Types of differential stains

A

Gram stain
Acid-fast stain

144
Q

Gram-positive bacteria have

A

thick peptidoglycan cell walls

145
Q

Gram-negative bacteria have

A

have thin peptidoglycan cell walls and a layer of lipopolysaccharides

146
Q

The first synthetic drugs classified bacteria into

A

gram-positive or gram-negative

147
Q

Steps of gram staining in my own words

A
  1. Application of crystal violet (purple dye)
  2. Application of iodine (mordant)
  3. Alcohol wash (decolorization)
  4. Application of safranin (counterstain)
148
Q

Acid-fast stain binds only to

A

bacteria that have a waxy material in their cell walls, which is not decolorized by acid-alcohol

149
Q

Acid-fast stain is used for the identification of

A

Mycobacterium
Nocardia

150
Q

Primary stain: Carbolfuchsin
Color of acid-fast:
Color of non-acid-fast:

A

Primary stain: Carbolfuchsin
Color of acid-fast: Red
Color of non-acid-fast: Red

151
Q

Decolorizing Agent: Acid-alcohol
Color of acid-fast:
Color of non-acid-fast:

A

Decolorizing Agent: Acid-alcohol
Color of acid-fast: Red
Color of non-acid-fast: Colorless

152
Q

Counterstain: Methylene Blue
Color of acid-fast:
Color of non-acid-fast:

A

Counterstain: Methylene Blue
Color of acid-fast: Red
Color of non-acid-fast: Blue

153
Q

Why is the Gram stain so useful?

A

Gram staining is useful since it allows us to distinguish whether microbial cells (bacteria) are gram-positive or gram-negative

154
Q

Which stain would be used to identify microbes in the genera Mycobacterium and Nocardia?

A
155
Q

Special stains used to

A

Used to distinguish parts of microorganisms

156
Q

Structures that can be distinguished with special stains

A

Capsule stain
Endospore stain
Flagella stain

157
Q

Capsules

A

are a gelatinous covering that do not accept most dyes

158
Q

Suspension of India ink or nigrosin contrasts

A

the background with the capsule, which appears as a halo around the cell

159
Q

Endospores

A

are resistant, dormant structures inside some cells that cannot be stained by ordinary methods

160
Q

Primary stain of endospores

A

malachite green, usually with heat

161
Q

What decolorizes endospores?

A

water

162
Q

Counterstain for endospores

A

safranin

163
Q

Spores appear green within

A

red or pink cells

164
Q

Flagella

A

Structures of locomotion

165
Q

Flagella staining uses a mordant and carbolfuchsin to thicken appearance of ________ making them visible under the light of a microscope

A

flagella

166
Q

What thickens the appearance of flagella?

A

mordant and carbolsfuschin

167
Q

How do unstained endospores appear? Stained endospores?

A

They appear contrasted and distinguishable from stored material. unstained appear under the light but are not distinguishable.

MICROBIOLOGY!225-80 (24 decks)

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