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Microbioloy > Chapter 2 microscopes > Flashcards

Chapter 2 microscopes Flashcards

1
Q

How do light waves react with materials

A

By being reflected, absorbed, or transmitted

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2
Q

when does reflection occur

A

when a wave bounces off of a material

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3
Q

When does absorbance occur

A

when a material captures the energy of a light wave

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4
Q

When does transmission occur

A

when a wave travels through a material, like light through glass

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5
Q

what is transmittance

A

the process of transmission

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6
Q

What is diffraction

A

when light waves interact with small objects or opening by bending or scattering

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7
Q

When is diffraction larger

A

when the object is smaller relative to the wavelength of the light

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8
Q

When does refraction occur

A

When light waves change direction as they enter a new medium

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9
Q

What is the refractive index

A

the extent to which a material slows transmission speed relative to empty space

(the extent in which it bends)

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10
Q

What happens when there are large differences in refractive indices of two materials

A

a large amount of refraction when light passes from one material to the other

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11
Q

What is the clarity of the image

A

resolution

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12
Q

what is resolving power

A

the distance at which it can still distinguish between two separate points that are close together

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13
Q

what is contrast

A

the difference between two or more parts of an object (light and dark areas of microbe)

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14
Q

what does refraction refer to

A

light bending as it passes through a substance such as air, water, gas and oil

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15
Q

What happens when light is refracted away from the lens

A

it is lost and the image loses resolution

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16
Q

when is immersion oil used

A

with the highest magnification of of the microscope

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17
Q

why does the 100X objective require immersion oil

A

It is so close to the side that when light passes from the slide into the air it gets refracted and is not captured by the lens

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18
Q

how does immersion oil help

A

it has a similar refractive index to glass somber light is captured.

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19
Q

Who first saw the cell through a microscope

A

Robert hooke

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20
Q

what kind of microscope did van Leeuwenhoek use

A

simple microscope (one lens)

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21
Q

what kind of microscope did Hooke use

A

compound microscope (objective and ocular lens)

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22
Q

Where is the ocular lens in a binocular compound microscope

A

Inside the eye piece

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23
Q

what is the interpulpillary distance

A

distance between pupils adjusting allows both eyes to focus together on the image

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24
Q

what is the objective lens

A

the lenses that are changed to increase magnification

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25
Q

what is total magnification

A

the sum of magnification from the objective and ocular lens

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26
Q

how do you calculate the total magnification

A

power of ocular lens is multiplied by the power of the objective lens.

ocular is usually 10X

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27
Q

what kind of microscope did Galileo use

A

compound microscope

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28
Q

what kind of microscope did Leeuwenhoek use

A

simple microscope

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29
Q

what did Robert Hooke observe through his microscope

A

he looked a sample of cork and was the first to observe cells

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30
Q

who invented the light microscope

A

Joseph Jackson lister

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31
Q

what are the types of light microscopes

A

Brightfield microscopes
dark field microscopes
phase contrast microscopes
differential interference contrast
fluorescence
confocal scanning laser
two-photon microscopes

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32
Q

describe the brightfieqld microscope

A

coumpound microscope with two or more lenses that produce a dark image on a bright background

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33
Q

What is the stage of a microscope

A

the platform where the specimen is set

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34
Q

What ;do they X-y mechanical stage knobs do

A

move the slide on the surface of the stage but does not raise or lower

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35
Q

what is the coarse focusing knob

A

knob for large scale movements

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36
Q

what is the fine focusing knob

A

used for small scale movements especially with more powerful lenses

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37
Q

why do images become dimmer with more magnification

A

there is less light per unit area of image

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38
Q

what provides light in a microscope

A

the illuminator

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39
Q

where does the light for the illuminator pass through

A

the condenser lens

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40
Q

what does the condenser lens do

A

focuses all of the light rays on the specimen to maximize illumination

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41
Q

What does the diaphragm do

A

Helps adjust the light striking the specimen

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42
Q

what is a rheostat

A

a dimmer switch that controls the intensity of the illuminator.

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43
Q

When is a fluorescent microscope the best choice

A

when observing organisms that fluoresce or can be tagged with a fluorescent antibody

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44
Q

how is a dark field microscope changed from a bright field

A

There is an opaque light stop block most light from the illuminator as it passes through the condenser producing a hollow cone o flight focused on the specimen. it shows bright images on a dark background. the light is deflected or scattered from specimen

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45
Q

When is a dark field microscope usefull

A

for creating high contrast, high resolution images without stains. great for live specimens.

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46
Q

how does a phase-contrast microscope work

A

uses refraction and interference caused by structures in a specimen to create high-contrast, high resolution images without staining. it alters wave lengths.

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47
Q

what are phase contrast microscopes good for looking at

A

Live specimens, organelles in eukaryotic cells
endospores in prokaryotic cell

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48
Q

What appearance is created with a differential interference contrast microscope

A

a high contrast image of living organisms with a three dimensional appearance

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49
Q

What are chlorophylls in fluorescence microscope

A

texas red
PITC
nucleic acid dyes
acridine orange

50
Q

What are fluorescence microscopes useful for

A

identify pathogens
find a species within an environment
find locations of particular molecules or structures in a cell

51
Q

what is immumofluorescence

A

a technique used to identify certain disease causing microbes by see what antibodies bind to them

52
Q

How does an electron microscope increase magnification and resolution

A

uses short-wavelength electron beams rather than light

53
Q

what are the two types of electron microscope

A

transmission electron microscope and the scanning electron microscope

54
Q

What are stains

A

dyes composed of organic compounds

55
Q

what is a chromophore

A

an ion in the dye that is colored

56
Q

What happens when ions are dissolved in water

A

the positively and negatively charged ions will separate

57
Q

what charge is bacteria

A

negative

58
Q

What is a positive stain

A

a stain with a positively charged chromophore so it sticks to the negative bacteria

59
Q

what is a negative stain

A

a negative charged chromophore that leaves the bacteria colorless

60
Q

What is differential staining

A

process that distinguishes between two groups of bacteria

61
Q

which gram bacteria are harder to treat

A

gram-negative

62
Q

What does a gram stain do

A

distinguishes between the cell wall components of bacteria

63
Q

what is the difference between gram negative and gram positive bacteria

A

gram positive bacteria have multiple layers of a wall and gram negative only have one surrounded by a membrane

64
Q

what does the primary stain dye

A

any bacteria

65
Q

what is the primary star of the gram stain

A

crystal violet (purple stain)

66
Q

what is the second step of the gram stain

A

mordant

67
Q

what is the mordant

A

iodine

68
Q

why is iodine the mordant

A

it will bind with crystal violet forming a complex

69
Q

what is the 3rd step in gram staining

A

decolorizing

70
Q

what is added in the decolorizing step

A

alcohol

71
Q

what does alcohol do to the stain

A

dehydrates the cell

72
Q

what happens after alcohol is added in a gram positive stain

A

crystal violet/ iodine complex dehydrates and becomes bound within the layers of walls so they retain the primary stain when rinsed

73
Q

what happens to gram-negative stains when they are rinsed

A

they are colorless

74
Q

what is the counterstain in the gram stain procedure

A

safranin (red stain)

75
Q

what does safranin do to gram negative stains

A

It will dye the the gram negative stain because they are colorless

76
Q

what colors are at the end of gram staining

A

Pink (gram -negative)
purple (gram positive)

77
Q

What is the primary stain in an acid-fast stain

A

carbolfuchsin (red dye)

78
Q

what happens to to acid fast cells when washed with acid

A

the retain the primary stain

79
Q

what is the decolorized in an acid-fast stain

A

acid alcohol

80
Q

what is the counterstain in an acid-fast stain

A

methan blue

81
Q

what does the counterstain in an acid-fast stain do

A

color non acid fast cells blue

82
Q

why is acid fast staining important

A

it distinguishes cells that are in the genus mycobacterium

83
Q

what are some diseases caused by myobacterium

A

TB
leprosy

84
Q

what do acid fast cells contain

A

a waxy coat called mycotic acid

85
Q

what is significant about acid-fast cells

A

they cannot be treated with general ABX and cannot be stained with gram staining procedure.

86
Q

What does endospore staining do

A

differentiates between bacteria that produce endospores and those that do not

87
Q

when are endospores produced

A

when the bacteria is about to die

88
Q

what do endospores have

A

a thick resistant wall surrounding the cells DNA

89
Q

how long can endospores remain doormant

A

up to 30 years

90
Q

what are endospores resistant to

A

extreme environmental factors such as heat, chemicals and PH

91
Q

what happens when endospores are activated

A

they become a vegetative cell that will reproduce in the environment or host

92
Q

what are some disease caused by endospore forming bacteria

A

botulism
tetanus
anthrax

93
Q

what is the primary stain in endospore staining

A

malachite green

94
Q

what is the decolorized in endospore staining

A

water

95
Q

what is the counter stain in endospore staining

A

safranin

96
Q

how are endospores stained

A

heat drives the primary stain into the endospore and it cannot be washed out.

endospore is green and the rest of the cell is red

97
Q

What is a capsule stain

A

differentiates between with a capsule or not

98
Q

what are capsules

A

a coating on the outside of the wall of some bacteria

99
Q

what capsules do

A

allow bacteria to resist the body immune defenses (phagocytosis

100
Q

What is phagocytosis

A

the process where white blood cells engulf and destroy foreign invaders

101
Q

what is virulence

A

a microbes ability to cause disease

102
Q

how does the capsule stain differ from other differential staining procedures

A

it is a negative staining process, the capsule appears as a halo around the cells

103
Q

What is flagella stain

A

a stain the differentiates between bacteria that possess flagella or not or determine the arrangement of flagella

104
Q

why is it important to determine the arrangement of flagella

A

to determine type of motility and classification

105
Q

why is flagella staining difficult

A

flagella are fragile and can break off during the process

106
Q

why is a mordant used in flagella staining

A

so they appear thicker

107
Q

What is fixation

A

attaching cells to a slide

108
Q

how is fixation achieved

A

heat fixing or chemically treating the specimen

109
Q

what does fixation do to a specimen

A

kills microorganisms while preserving the integrity of cellular components

110
Q

how do you heat fix a sample

A

spread a thin layer of sample on the slide and briefly heat slide

111
Q

what chemical agents can be used in chemical fixing

A

acetic acid
ethanol
methanol
formaldehyde
glutaraldehyde

112
Q

when are chemical agents preferred for fixing

A

tissue specimens

113
Q

What is a basic dye

A

When the positively charged ion is the chromophore

114
Q

what is an acidic dye

A

when the negative ion is the chromophore

115
Q

What are commonly used acidic dyes

A

fuchsin
eosin
rose bengal

116
Q

What are the steps in gram staining

A
  1. primary stain (all cells purple)
  2. mordant (sets or stabilizes stain)
  3. decolorizing agent
  4. counterstain (cells are pink now if gram neg)
117
Q

What considerations need to be taken into account when gram staining old cells

A

they may have damaged cells wall making them appear gram-negative when they are not

118
Q

what things can affect gram stain results

A

old cells
leaving decolorizer on too long

119
Q

what should you do if decolorized was left on too long and some look gram positive and others gram negative

A

consider them all gram positive instead of a mixed culture

120
Q

what is the difference between the kinyoun technique and the ziehl-neelsen technique of acid fast staining

A

the ziehl nelson method uses heat to infuse the carbolfuchsin

121
Q

benefits of dark field microscope

A

you can view shape and motility of unstained live organisms
great for syphiis

122
Q
A

Microbioloy (10 decks)

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