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Practical 1 Flashcards

1
Q

what does it mean that microorganisms are ubiquitous

A

found in any environmental condition

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2
Q

what is a pure culture

A

culture containing a single unadulterated species

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3
Q

what does survival and continued growth of microorganisms require

A

nutrients and a favourable growth environment

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4
Q

what is a culture medium

A

soluble low molecular weight substances (derived from enzymatic degredation of complex nutrients)

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5
Q

what is agar

A

used for solid media, extract of seaweed, is a complex carbohydrate composed mainly of galactose

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6
Q

why is agar a good solidfying agent

A

liquid at 100c and solid at 40c

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7
Q

what percent of agar is needed to have a solid media

A

1.5-1.8 percent

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8
Q

what is the main advantage to using agar slants in test tubes

A

best for maintaining pure cultures

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9
Q

whats the purpose of agar deep tubes

A

used for the study of gaseous requirements of microorganisms

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10
Q

what is the purpose of agar plates

A

large surface areas for the isolation and study of microorganisms

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11
Q

what is sterilization

A

process of rendering a medium or material free of all forms of life

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12
Q

what is the main function of aseptic technique

A

maintaining sterile where necessary and avoid external contamination

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13
Q

where can you use broth mediums

A

only in test tubes, never in petri dishes

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14
Q

what is a way to maintain aseptic technique in mediums

A

plastic lids in petri plates, metal or plastic caps in test tubes (historically cotton plugs)

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15
Q

how must petri dishes be incubated and why

A

incubated inverted (larger cap down) to prevent condensation from dripping

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16
Q

what is subculturing

A

microorganisms being transferred from one vessel to another

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17
Q

what are wire loops made of

A

inert metals such as nichrome or platinum

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18
Q

what is the function of an incubator

A

maintains a temperature for the microorganisms that is optimal for their growth

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19
Q

what is the function of a fridge

A

will slow or stop the growth of most microorganisms to be able to use for example as stock cultures

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20
Q

how do you transfer microorganisms from a tube to a petri plate

A

flame loop, remove cap, flame neck of tube, collect sample, flame neck of tube, cap, open petri plate, spread sample, lid petri plate, flame loop

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21
Q

what is one of the best ways to get a pure culture from a mixed culture

A

streak plate

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22
Q

what is a colony

A

individual macroscopically visible masses of microbial growth on solid medium representing replication of single microorganism

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23
Q

what is a streak plate

A

essentially a dilution series on solid media

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24
Q

what is colony morphology

A

visible collection of microorganism cells growing on the surface of solidified media

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25
Q

for agar slants what are the terms for abundance of growth

A

none, slight, moderate, large

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26
Q

for agar slants what are the terms for optical characteristics

A

opaque, translucent, transparent

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27
Q

for agar slants what are the form types

A

filiform, echinulate, beaded, effuse, arborescent, rhizoid

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28
Q

what is filiform growth

A

continuous threadlike growth with smooth edges

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29
Q

what is echinulate growth

A

continuous threadlike growth with irregular edges

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30
Q

what is beaded growth

A

nonconfluent to semiconfluent colonies

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31
Q

what is effuse growth

A

thin spreading growth

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32
Q

what is arborescent growth

A

treelike growth

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33
Q

what is rhizoid growth

A

root like growth

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34
Q

what are the consistencies for agar slants

A

dry, buttery, mucoid

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35
Q

for agar plates what are the form types

A

circular, irregular, rhizoid

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36
Q

what are the margin types for agar plates

A

entire, lobate, undulate, serrate, filamentous

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37
Q

what is entire for agar plates

A

sharply defined and even

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38
Q

what is lobate for agar plates

A

marked indentations

39
Q

what is undulate in agar plates

A

wavy indentations

40
Q

what is filamentous in agar plates

A

threadlike spreading edge

41
Q

what are the elevation types in agar plates

A

flat, raised, convex, umbonate

42
Q

what is umbonate in agar plates

A

raised with an elevated convex central region

43
Q

who pretty well invented the microscope

A

leeuwenhoek

44
Q

what are the present day microscope magnification capabilities

A

greater than 250,000X

45
Q

what are the two basic types of microscopes

A

light or electron

46
Q

what are the types of light microscopes

A

brightfield, darkfield, phase-contrast, fluorescent

47
Q

what kind of microscope uses uv light

A

fluorescence

48
Q

how do electron microscopes work

A

electron beams and magnets to observe submicroscopic particles

49
Q

what are the essential features of a brightfield microscope

A

2 lens system, tungsten light, specimen appears dark against a bright background, no contrast, good for stained slides not for living cells

50
Q

what are the essential features of a darkfield microscope

A

condenser system modified so specimen isnt directly illuminated, specimen appears bright on a dark background, can observe living cells better than brightfield

51
Q

what are the essential features of phase contrast microscope

A

can observe in unstained state, specimen appears dark against a bright background, light refracts to show structures of organism

52
Q

what are the essential features of a fluorescent microscope

A

see organisms tagged with fluorescent dyes, uv light for illumination, used for antigen-antibody interactions, colour on black background

53
Q

what are the essential features of an electron microscope

A

magnification up to 1 million x, illuminated by beam of electrons, focusing is done by electromagnets instead of optics, scanning for surface images, transmission for thin filaments

54
Q

what is the stage of a microscope

A

fixed platform with opening for light passage, typically mechanical and can be moved horizontally and vertically

55
Q

what is the abbe condenser

A

directly under the stage and has two sets of lenses to collect and concentrate light, also contains an iris diaphragm to regulate the amount of light

56
Q

what is the body tube

A

above the stage and attached to arm of microscope, houses lens system to magnify specimen, body tube is lowered and raised by the adjustment knobs

57
Q

how do you manipulate magnification

A

occular lens and objective lens

58
Q

what is numerical aperture

A

function of the diameter of the objective lens in relation to its focal length

59
Q

the ____ the wavelength the ___ the resolving power

A

the shorter the wavelength the greater the resolving power

60
Q

____ wavelengths for ___ resolution

A

short wavelengths for better resolution

61
Q

what is resolving power dependent on

A

refractive index and wavelength

62
Q

what is the refractive index

A

bending power of light passing through air from the glass slide to the objective lens

63
Q

what is the correct setup for koehler illumination

A

eye and specimen focused, specimen and field stop focused

64
Q

what is the function of koehler illumination

A

illuminate specimen on slide, as light passes through specimen it should be parallel and evenly illuminated–its the best image you can get

65
Q

what does it mean that a substage condenser uses a 2 conjugate plane system

A

if one is at focus the other is completely defocused but completely parallel

66
Q

what are the two parts to a conjugate plane system

A

the first is the light source, aperature stop, objective. the second is field stop, specimen, eyepiece/eye

67
Q

what is the formula for resolution

A

wavelength/2*NA (NA is numerical aperature)

68
Q

what is numerical aperture

A

measure of light gathering ability of a lens

69
Q

what is the refractive index of oil

70
Q

what is the refractive index of air

71
Q

what is numerical aperture of a dry lens

72
Q

what is numerical aperture of oil lens

73
Q

what is the longest wave length

74
Q

what is the shortest wavelength

75
Q

what is a stain

A

an organic compound containing benzene ring plus a chromophore and an auxochrome group

76
Q

what is the function of chromophore

A

brings colour

77
Q

whats the function of auxophore

A

binds the colour of chromophore to fibers or tissues

78
Q

are acidic stains anionic or cationic

79
Q

what are acidic stains used for

A

gram negative bacteria

80
Q

what are basic stains used for

A

gram positive bacteria

81
Q

whats an example of an acidic stain

A

picric acid, nigrosine, congo red

82
Q

whats an example of a basic stain

A

crystal violet, methylene blue, safranin

83
Q

what are the two basic staining techniques

A

simple or differential

84
Q

why is it bad to have too much bacteria on a slide

A

diminishes the amount of light that is able to pass through

85
Q

why is heat fixation required

A

helps anchor bacteria to slide, and kills bacteria

86
Q

what is streptococcus

A

chain of cocci

87
Q

what is staphlococcus

A

unorganized cluster of cocci

88
Q

what is sarcinia

A

cube of cocci

89
Q

how do you do a positive stain

A

put basic stain on slide for 30 seconds, rise excess dye off

90
Q

how do you do a negative stain

A

no heat fixation needed, nigrosin at one end of slide, bacteria in nigrosin drop, spread dot to other end of slide with another slide at a 45 degree angle

91
Q

how many chemical reagents are needed for differential staining

A

4 chemical reagents

92
Q

what is the strength of differential staining

A

you can differentiate gram negative and gram positive bacteria on the same slide

93
Q

how do you do a differential stain

A

start with heat fixed slide, apply basic stain (crystal violet), wash, grams iodine, wash, alcohol, wash, other basic stain, wash

94
Q

what is the function of grams iodine

A

kills bacteria and increases cells affinity for a stain

Microbiology (6 decks)

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