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Microbiology > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Most important tool for studying microorganisms

A

Microscope

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2
Q

Use visible light to observe objects

Magnify images approximately 1,000x

A

Microscope

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3
Q

can magnify images in excess of 100,000x

A

Electron microscope,

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4
Q

can view individual atoms

A

Atomic-­‐force microscope

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5
Q

Light passes through specimen, then through series of magnifying lenses

A

Light Microscopy

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6
Q

Most common and easiest to use

A

bright-­field microscope

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7
Q
A

Magnification
Resolution
Contrast

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8
Q

the ability of a microscope to determine two closely related objects as separate objects

A

resolution

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9
Q

maximum resolving power of most bright field microscopes

A
  1. 2 um
    - This is sufIicient to see most bacterial structures
    - Too low a resolution to see viruses
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10
Q

Microscope has two magnifying lenses

A

compound microscope

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11
Q

two lenses on compound microscope

A

oscular and objective lens

  • MagniIication is equal to the factor of the ocular x the objective
  • 10x X 100x = 1,000
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12
Q

Uses light condenser to concentrate light on sample

A

BrightIield Microscope

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13
Q

deIined by the minimum distance between two objects where those objects appear as separate objects

A

Resolving power

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14
Q

depends on the quality of lenses and wavelength of illuminating light

A

Resolution

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15
Q

The first to observe bacteria, achieved a reolution of about 1.4 um

A

AvL

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16
Q

Resolution is enhanced with lenses of higher magniIication (100x) by the use of

A

immersion oil

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17
Q

The oil reduces

A

light refraction

  • Light bends as it moves from glass to air
  • oil bridges the gap between the specimen slide and lens and reduces refraction
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18
Q

immersion oil has nearly same refractive index as

A

glass

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19
Q

Reflects the number of visible shades in a specimen

A

contrast

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20
Q

higher contrast for microscope is achieved through

A

specimen staining

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21
Q

Amplifies differences between refractive indexes of cells and surrounding medium

A

Phase-­Contrast

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22
Q

Uses set of rings and diaphragms to achieve resolu:on

A

Phase-‐Contrast

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23
Q

reflects number of visible shades, this is great except it kills some of the cells

A

Phase-Contrast

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24
Q

Causes specimen to appear three dimensional

A

Interference Scope

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25
Q

Most frequently used interference scope is

A

Nomarski differen:al interference contrast

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26
Q

Used to observe organisms that are naturally fluorescent or are flagged with fluorescent dye

A

Fluorescence Microscope

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27
Q

absorbs ultraviolet light and emits visible light

A

Fluorescent molecule

-Image fluoresces on dark background

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28
Q

Computer used to re-­construct three dimensional image of thicker structures

A

Confocal Scanning Laser Microscope

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29
Q

Provides detailed sectonal views of internal structures of an intact organism

A

Confocal Scanning Laser Microscope

30
Q

Laser sends beam through sectons of organism and then Computer constructs 3-­‐D image from sec:ons

A

Confocal Scanning Laser Microscope

31
Q

Reverse image

-Specimen appears bright on a dark background

A

Dark-­‐Field Microscope

32
Q

“Like a photographic negative”

A

Dark-­‐Field Microscope

33
Q

Achieves image through a modified condenser

A

Dark-­‐Field Microscope

34
Q
  • Used to observe fine detail
  • Directs beam of electrons at specimen
  • Electrons pass through or sca7er at surface
A

Transmission Electron Microscope (TEM)

35
Q

Shows dark and light areas, darker areas more dense

A

Transmission Electron Microscope (TEM)

36
Q

specimen preparation for TEM

A
  • thin sectioning
  • freeze fracturing or freeze etching
  • can often introduce artifacts
37
Q
  • Used to observe surface detail

- Beam of electrons scan surface of specimen

A

Scanning Electron Microscope (SEM)

38
Q

Specimen coated with metal, usually gold

A

Scanning Electron Microscope (SEM)

39
Q
  • Electrons are released and reflected into viewing chamber

- Some atomic microscopes capable of seeing single atoms

A

Scanning Electron Microscope (SEM)

40
Q

set out to examine the details of rabies virus

A

Eran Perlson- set up a system to grow asymmetric nerve cells in observation chamber and use live cell imaging to track hoe rabies virus particles are transported along the axons.

41
Q

Most common strategy to change contrast and observe organisms

A

Dyes and Staining

42
Q

using stains are made of

A

organic salts

43
Q

carry (+) or (-­‐) charge on the molecule

Divided into basic or acidic based on charge

44
Q

carry positive charge and bond to cell structures that carry negative charge

A

basic dyes

-commonly stain the cells

45
Q

carry negative charge and are repelled by cell structures that carry negative charge

A

Acidic dyes

-commonly stain the background

46
Q
  • uses one stain
  • Allows for increased contrast between cell and background
  • All cells stained the same color
  • No differentiation between cell types
A

Simple stain

ex/ hematopoietic cell smear

47
Q

-Used to distinguish one cell type from another

A

DifferenAal Stains

48
Q

Two most common bacterial differenAal stains

A

gram stain

acid fast stain

49
Q
  • Most widely used procedure for staining bacteria

- Dr. Hans Christian Gram

A

gram stain

50
Q

Stained purple/blue

A

gram positive

51
Q

stained red or pink

A

gram negative

52
Q

primary stain in gram stain

A

crystal violet

53
Q

mordant in gram stain

A

grams iodine

-fixes primary dye in cell

54
Q

decolorizer in gram stain

A

usually alcohol

-removes primary dye from gram negative cell

55
Q

counter or secondary stain in gram stain

A

safranin

-recolors cells that lose stain through decolorization

56
Q

Used to stain organisms that resist conventional staining

A

Acid-­‐fast Stain

57
Q

Acid fast staining is particularly useful in staining members of genus..

A

Mycobacterium

58
Q

High lipid concentraAon in cell wall prevents uptake of dye, ‘waxy’ mycolic acid

A

Acid-­‐fast Stain

59
Q
  • Use heat to facilitate staining

- Once stained difficult to decolorize

A

Acid-­‐fast Stain

60
Q

Presumptive identification in diagnosis of clinical specimens

A

Acid-­‐fast Stain

61
Q

primary dye acid fast

A
  • carbol fuchsin

- colors acid fast bacteria red

62
Q

decolorizer acid fast

A
  • generally acid alcohol

- removes stains from non acid fast bacteria

63
Q

counter stain acid fast

A
  • methylene blue

- colors non acid fast bacteria blue

64
Q
  • Example of negative stain

- Allows capsule to stand out around organism

A

Capsule stain

65
Q

can appear as clear region in Gram or simple stains

A

Endospore stain

66
Q

uses gentle heat to facilitate staining

A

Endospore stain

67
Q

Staining increases diameter of flagella

Makes visible with light microscope resolution

A

Flagella stain

68
Q

arrangement of prokaryotic cells depends on

A

plan of division

69
Q

architecture can specify division planes in Staphylococcus aureus.

A

Peptidoglycan

70
Q
  • static in location
  • Extrapolymeric substance (EPS)
  • dynamic community structure helps recruitment of nutrients and survival in harsh conditions
71
Q

rigidity of bacterial cell wall is due to..

A

peptidoglycan- ONLY FOUND IN BACTERIA

Microbiology (24 decks)

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