Microscopy Flashcards

1
Q

use of a microscope to magnify objects too small
to be visualized with the naked eye so that their
characteristics are readily observable

A

MICROSCOPY

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2
Q

APPLICATIONS OF MICROSCOPY

A
  1. Rapid preliminary organism identification
  2. Rapid final identification of certain organisms
  3. Detection of different organisms present in the same specimen
  4. Detection of organisms not easily cultivated in the laboratory
  5. Evaluation of patient specimens for the presence of cells indicative of inflammation or contamination
  6. Determination of an organism’s clinical significance
  7. Provide pre-culture information
  8. Determine which tests and methods should be used for identification and characterization of
    cultivated organisms
  9. Provide a method for investigating unusual or
    unexpected laboratory test results
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3
Q

TYPES OF MICROSCOPY

A

BRIGHT-FIELD (LIGHT) MICROSCOPY
PHASE-CONTRAST MICROSCOPY
FLUORESCENT MICROSCOPY
DARK-FIELD MICROSCOPY
ELECTRON MICROSCOPY

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4
Q

visible light is passed through the specimen and then through a series of lenses that bend the light in a manner that results in magnification of the organisms present in
the specimen

A

PRINCIPLES BRIGHT-FIELD (LIGHT) MICROSCOPY

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5
Q

PRINCIPLES OF LIGHT MICROSCOPY

A

A. MAGNIFICATION
B. RESOLUTION
B.1 RESOLVING POWER
C. CONTRAST

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6
Q

→extent to which detail in the magnified object is maintained

A

RESOLUTION

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7
Q

→ability of the lenses to distinguish fine detail and structure

A

RESOLUTION

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8
Q

→determined by numerical aperture and wavelength of light

A

RESOLUTION

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9
Q

→closest distance between two objects that
when magnified still allows the two objects to be distinguished from each other

A

RESOLVING POWER

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10
Q

FACTORS AFFECTING RESOLVING POWER

A

IMMERSION OIL

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11
Q

(TRUE OF FALSE)
Shorter the wavelength of light used in the instrument, the greater the resolution

A

TRUE

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12
Q

specific optical and viscosity characteristics
designed for use in microscopy

A

IMMERSION OIL

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13
Q

→used to fill the space between the objective lens and the glass slide onto which the specimen has been affixed

A

IMMERSION OIL

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14
Q

→enhances resolution by preventing light rays from dispersing and changing wavelength after passing through the specimen

A

IMMERSION OIL

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15
Q

measure of the light-bending ability of
a medium

A

Refractive Index

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16
Q

required for optimal detection and
characterization of bacteria

A

1000× magnification

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17
Q

needed to make objects stand out from the background

A

CONTRAST

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18
Q

achieved by staining techniques that highlight organisms and
allow them to be differentiated from one another and from
background material and debris

A

CONTRAST

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19
Q

Kohler Illumination

A

designed to provide maximum illumination and resolution when observing images using a microscope

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20
Q

detailed examination of internal structures in living microorganisms

A

PHASE-CONTRAST MICROSCOPY

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21
Q

not necessary to fix or stain the
specimen

A

PHASE-CONTRAST MICROSCOPY

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22
Q

based on the wave nature of light ray

A

PRINCIPLE OF PHASE-CONTRAST MICROSCOPY

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23
Q

light rays can be in phase (their peaks and valleys
match) or out of phase

A

PRINCIPLE OF PHASE-CONTRAST MICROSCOPY

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24
Q

wave peak of light rays from one source coincides with the wave peak of
light rays from another source

A

Reinforcement (relative brightness)

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25
Q

wave peak from one light
source coincides with the wave trough from another light source

A

Interference (relative darkness)

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26
Q

Set of light rays

A

a. direct from light source
b. reflected or diffracted from a particular
structure in the specimen

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27
Q

scattering of light rays as they touch a
specimen’s edge

A

Diffraction

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28
Q

Two sets of light rays are brought together, form an image of the specimen on the ocular lens, containing areas that are relatively light and through shades of _______

A

gray, to black

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29
Q

PRINCIPLE OF FLUORESCENT MICROSCOPY

A

Fluors or Fluorochromes

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30
Q

→raised to a higher energy level after absorbing ultraviolet
(excitation) light

A

Fluors or Fluorochromes

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31
Q

→return to their normal, lower energy state, they release
excess energy in the form of visible (fluorescent) light

A

Fluors or Fluorochromes

32
Q

(TRUE OR FALSE)
Fluorescing objects appear brightly against a light background

A

(False) Fluorescing objects appear brightly against a DARK background

33
Q

FILTERS IN FLUORESCENT MICROSCOPY

A

Excitation filter
Barrier filter

34
Q

passes light of the desired wavelength to excite the fluorochrome

A

Excitation filter

35
Q

prevents the excitation wavelengths from damaging the eyes of the observer

A

Barrier filter

36
Q

FLUORESCENT DYES

A

Acridine Orange
Auramine
Fluorescein Isothiocyanate (FITC)
Calcofluor White

37
Q

requires BLUE excitation light

A

Acridine Orange
Auramine
Fluorescein Isothiocyanate (FITC)

38
Q

(WAVELENGTH)
✓Acridine Orange, Auramine, Fluorescein Isothiocyanate
(FITC)
Exciter filter:
Barrier filter:

A

450-490 wavelength
515 wavelength

39
Q

requires a VIOLET excitation light

A

Calcofluor White

40
Q

(WAVELENGTH)
Calcofluor White
Exciter filter:
Barrier filter:

A

355-425 wavelength
460 wavelength

41
Q

→ direct chemical interaction between the fluorescent dye and
a component of the bacterial cell

A

FLUOROCHROMING

42
Q

Advantage of FLUOROCHROMING

A

enhances contrast and amplifies the observer’s ability
to detect stained cells tenfold greater than light microscopy

43
Q

Examples of FLUOROCHROMING

A

✓Acridine orange stain
✓Auramine-rhodamine stain
✓Calcofluor white stain

44
Q

binds to nucleic acid

A

ACRIDINE ORANGE

45
Q

→used to confirm the presence of bacteria in blood
cultures

A

ACRIDINE ORANGE

46
Q

→stains all nucleic acids—nonspecific

A

ACRIDINE ORANGE

47
Q

→bright orange fluorescence

A

ACRIDINE ORANGE

48
Q

→does not discriminate between gram-negative and gram-
positive bacteria

A

ACRIDINE ORANGE

49
Q

→used for detection of cell wall–deficient bacteria grown in
culture

A

ACRIDINE ORANGE

50
Q

→have affinity to waxy mycolic acids in the cell walls of
mycobacteria

A

AURAMINE-RHODAMINE

51
Q

→non-specifically bind to nearly all mycobacteria

A

AURAMINE-RHODAMINE

52
Q

→appear bright yellow or orange against a greenish
background

A

AURAMINE-RHODAMINE

53
Q

→used to enhance detection of mycobacteria directly in
patient specimens

A

AURAMINE-RHODAMINE

54
Q

→initial characterization of cells grown in culture

A

AURAMINE-RHODAMINE

55
Q

→bind in the cell walls of fungi

A

CALCOFLUOR WHITE

56
Q

→directly detect fungi in clinical material

A

CALCOFLUOR WHITE

57
Q

→observe subtle characteristics of fungi grown in culture

A

CALCOFLUOR WHITE

58
Q

→visualize some parasites such as microsporidia

A

CALCOFLUOR WHITE

59
Q

→antibodies are conjugated to a fluorescent dye

A

IMMUNOFLUORESCENCE

60
Q

→dye-antibody conjugate detect, or “tag,” specific microbial
agents

A

IMMUNOFLUORESCENCE

61
Q

→microorganisms become readily detectable by fluorescent
microscopy

A

IMMUNOFLUORESCENCE

62
Q

→combines the amplified contrast provided by fluorescence with the specificity of antibody- antigen binding

→Legionella spp., Bordetella pertussis, and Chlamydia trachomatis

A

IMMUNOFLUORESCENCE

63
Q

Example:
FITC→ intense, APPLE GREEN fluorescence →most commonly
used

A

IMMUNOFLUORESCENCE

64
Q

→involves the alternation of microscopic technique rather than
the use of dyes or stains to achieve contrast

A

DARK-FIELD MICROSCOPY

65
Q

→condenser does not allow light to pass directly through the
specimen but directs the light to hit the specimen at an oblique
angle

A

DARK-FIELD MICROSCOPY

66
Q

→only light that hits objects will be deflected upward into the
objective lens for visualization

A

DARK-FIELD MICROSCOPY

67
Q

→other light that passes through the specimen will miss the
objective, making the background a dark field

A

DARK-FIELD MICROSCOPY

68
Q

→ used to detect SPIROCHETES

A

DARK-FIELD MICROSCOPY

69
Q

Appear extremely bright against a black field

A

DARK-FIELD MICROSCOPY

70
Q

uses electrons instead of light to visualize small object

A

ELECTRON MICROSCOPY

71
Q

electrons are focused by electromagnetic fields and form an image on a fluorescent screen

A

ELECTRON MICROSCOPY

72
Q

magnifications in excess of 100,000×

A

ELECTRON MICROSCOPY

73
Q

ELECTRON MICROSCOPY
Two General Types

A
  1. TRANSMISSION ELECTRON MICROSCOPE (TEM)
  2. SCANNING ELECTRON MICROSCOPE (SEM)
74
Q

passes the electron beam through objects and allows visualization of internal structures

A

TRANSMISSION ELECTRON MICROSCOPE (TEM)

75
Q

uses electron beams to scan the surface of objects and provides three-dimensional views of surface structures

A

SCANNING ELECTRON MICROSCOPE (SEM)