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Microbiology 210 > Methods > Flashcards

Methods Flashcards

1
Q

Light microscopes are considered…. since they have two lenses

A

Compound microscopes

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2
Q

Types of compound microscopes

A

Bright-field

dark field

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3
Q

Lenses that work together to magnify objects

A

Objective and ocular

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4
Q

Objectives are composed of several lens elements that magnify the object first called the …. which produces….

A

Primary magnification - real image

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5
Q

the —- is composed of several lens elements that magnify the real image, called the

A

Ocular … Secondary magnification

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6
Q

The secondary magnification produces as —– which is seen at —-

A

Virtual image —- eye point

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7
Q

Total Magnification

A

Product of the objective and ocular lens

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8
Q

Resolving power

A

Resolution - limits useful magnification for compound microscopes

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9
Q

Stage

A

Where the specimen is placed

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10
Q

Two adjustment knobs

A

Course - primary focusing

Fine - secondary focusing

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11
Q

Parfocality

A

Ability to move from one objective to another while using only fine adjustment knob

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12
Q

Working distance

A

Distance b/w specimen on the slide and objective lens when in focus

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13
Q

As magnification increases

A

The field of view decreases

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14
Q

As magnification increases,

A

More light is needed.

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15
Q

Why is light conserved in oil?

A

Glass and oil have same refractive indexes

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16
Q

Absorption

A

Light passes through specimen

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17
Q

Refracted

A

Light is reflected off specimen

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18
Q

Phasecontrast

A

Differentiates between specimens of different densities

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19
Q

Fluorescent

A

Koon’s fluorescent antibody technique

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20
Q

Resolving power

A

Minimum distance that can exist between two object and still allow the two objects to be seen as separate

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21
Q

Magnification - resolution relationship

A

As you increase magnification, resolution increases until about 1000x, at which time there is an inverse relationship between the two

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22
Q

Light is the portion of the spectrum of electromagnetic waves that is visible to the human eye and are between

A

400-700nm

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23
Q

Bright field microscopy technique normally used for

A

Study of live or preserved/stained material. Common multipurpose scope

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24
Q

Dark field microscope is equipped with ______ condenser and an objective with _______ aperture.

A

Dark-field

Low numerical

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25
Result of a dark field microscope when viewing:
Only peripheral light reflected off the sides of the specimen enter the objective
26
Dark field microscopy is best to view
Living, unstained orgs | Examples: syphilis studies because it provides a specimen outline with reduced internal cellular details
27
Fluorescence microscope
Microscope is furnished with an ultraviolet radiation source and a filter that protects the eyes
28
Def; Fluorescence
Ability to absorb short wavelengths of light and give off light at a longer wavelength that can be seen with use of special filters
29
Explain prep for fluorescent scope use
Specimen is first coated with or placed in contact with fluorescent molecule. Stained with fl. Dyes or combined wit fl. Antibodies; illumination by UV radiation causes light to be given off, forming an image
30
Wide use of fl. Microscopy
Diagnosis of infections caused by certain bacteria, protozoa, fungi and viruses
31
Phase contract microscope
Equipped with a special condenser contains and annular ring shaped diaphragm.
32
Diaphragm function on phase contract scope
Allows direct light to pass through condenser focusing light on specimen and a refraction plate in the objective lens. Direct and reflected or diffracted light rays are brought together in phase to form the image of the specimen.
33
Application of phase contrast
Locating structures within live, unstained cells that are not seen under other scopes
34
Electron microscopes are
Use electron beams instead of life; all aspects controlled by electromagnets instead of glass. Have greater resolving power b/c of short wavelengths of the electron beams
35
TEM use
Beam of electrons passed through 20-100nm sections of specimen. Seen on a screen. Contrast can be increased by staining or soaking specimen in metals. Used to eye detailed structures on preserved material (dead).
36
TEM reveals
Ultrastructure of cells
37
SEM
Produces three dimensional image of specimen, offering surface detais
38
How SEM works
Electron beams scan back and forth over intact, metal coated specimen from the top Electrons leaving surface of the specimen picked up by detector Electron patter displayed as image on television screen or photographic film
39
Resolving power (resolution)
The ability of lenses to distinguish between two points a specified distance apart
40
Types of preparations for light microscopic examinations
Wet mount/hanging drops: suspension in liquid | Dried, fixed, and stained smears
41
Wet mount and hanging drop techniques... What is the quality of the resolution?
Wet mount: place liquid suspension of org on a slide and cover with a slip Drop: suspension place on cover slip, positioned over a well on depression slide Poorer than in dyed preparation
42
Staining techniques offer
Greater resolution because of color contrast
43
Positive stains use _____ dyes which stain _______
Basic Cells or cell parts
44
Simple stains
Positive stain One dye used to see morphology and cell arrangement
45
Differential stains
Positive stain Use more than one reagent to see differentiation between cells and cell parts
46
Gram stain
Differential stain Groups gram - and gram + cells
47
Acid Fast stain
Positive stain Bacteria that cause tuberculosis and hansen's disease are acid fast; most others are not
48
Giemsa stain
Positive stain Used to detect parasites in blood
49
Endospore stain
Positive stain Detects presence of endospores
50
Capsule stain and Flagella stain
Positive stains
51
Negative stain
Use acidic dyes that stain background around cells and leave cells colorless; can see shape and arrangement better
52
Stains have ______ significance
Practical diagnostic
53
Streak plate method
Inoculum spread over solid culture with loop
54
Spread plate method
Inoculum spread over surface of a solid medium with spreader
55
Pour plate method
Inoculum mixed in melted agar medium and poured into sterile petri dish
56
Enrichment culture
Culture medium used for preliminary isolation that favors the growth of a particular microorganism (blood agar, glucose, etc)
57
Stock cultures
Preserved for study and reference
58
Stock culture preservation
Short - refrigeration at 0-10 celsius Long - liquid nitrogen at -196 celsius or lyophilization
59
Culture (def)
Observable growth in or on a culture medium
60
Inoculation
Introduction of a tiny sample of cells into medium that encourages growth
61
Only dead specimens can be viewed with
Electron microscope
62
Light microscopes have ..... lenses instead of electromagnetic beams
Glass lenses
63
TEM magnification
500,000X
64
SEM magnification
200,000-250,000x
65
1000-2000x
Light microscopes
66
Light microscope resolving power
0.2-0.3um
67
TEM resolving power
0.0001um
68
SEM resolving power
0.02um
69
Ultrastructure
Sub microscopic structure
70
Resolving power of light
Wavelength of light / 2x Numerical Aperture

Microbiology 210 (7 decks)

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