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Microbiology > Chapter 3: Microscopy And Staining > Flashcards

Chapter 3: Microscopy And Staining Flashcards

1
Q

Nanometers (nm)

A

10^-9

- measure viruses

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2
Q

Micrometers (um)

A

10^-6

- measure bacteria

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3
Q

Light properties

A

Wavelength
Resolution
Light travel

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4
Q

Wavelength (lambda)

A

Length of a light ray

  • measure distance between two adjacent peaks or troughs
  • average visible light wavelength is .55um
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5
Q

Resolution

A

Ability to separate two objects as distinct

- the shorter the wavelength of light, the better resolution

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6
Q

Reflection

A

Light bounces off the object

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7
Q

Transmission

A

Passes through the object

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8
Q

Absorption

A

Light is absorbed by the object

- luminescence can occur (wavelength is changed and re-emitted by the object)

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9
Q

Florescence (glow)

A

Re-emitted light is only visible when the object is being irradiated (given light)

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10
Q

Phosphorescent (glow in the dark)

A

Light continues to be re-emitted after irradiation stops

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11
Q

Refraction

A

Light bends as it passes through the media

- oil prevents refraction in microscope

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12
Q

Diffraction

A

Light bending around a split

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13
Q

Bright field microscopy

A

Cells are slightly darker on a light background

- difficult to see without staining

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14
Q

Dark field microscopy

A

Cells appear light on a dark background

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15
Q

Phase contrast microscopy*

A

A special condenser and objective lenses are used to distinguish small differences in index of refractions
- can view living organisms

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16
Q

Nomarski (differential indifference)*

A
  • same ideas as phase contrast, but focus is on a single level or shorter depth of field
  • looks 3D
  • can view living organisms
17
Q

Ultraviolet light

A

Short wavelength to make the object fluoresce

18
Q

Confocal microscopy (UV)

A

Shows higher resolution than fluorescent

19
Q

Digital microscope

20
Q

Electron microscope

A

Uses electron beams (not light) and electromagnets to help focus on the image
- have shorter wavelengths than visible light rays*

21
Q

Transmission electron microscopy (TEM)

A
  • Provides highest level of magnification
  • Prepare super thin slices of the specimen
  • can magnify up to 500,000x
22
Q

Scanning electron microscopy (SEM)

A
  • Coat specimen with metal that reacts with electron beam to produce image
  • looks 3D
23
Q

Wet mount

A
  • Cover a drop of specimen with coverslip on slide

- Allows you to see a living organism’s size, shape, motility

24
Q

Hanging drop

A
  • Hang a drop of specimen from coverslip into a well on depression slide
  • provides better view of motility
25
Q

Smear

A
  • place cells on a glass slide
  • let them air dry
  • heat fix them to adhere them to slide
  • kills cells
26
Q

Acidic stains

A
  • Negatively charged
  • Stain positively charged glass, not cells
  • Cells appear white on a dark background
  • Also called negative stains
27
Q

Basic stains

A
  • Positively charged
  • Stain negatively charged cells
  • Cells appear dark on a light background
  • Also called a direct stain
28
Q

Simple stain

A
  • Uses a single dye

- Shows size, shape, arrangement

29
Q

Differential stain

A
  • Use more than one dye to differentiate cell types
30
Q

Gram stain

A
  • Used to distinguish cells based on cell wall
    1. Color everything purple with crystal violet dye (primary stain)
    2. Add iodine as a mordant to set the stain
    3. Add ethyl alcohol decolorizer
    4. Add safranin counterstain to visualize gram negative cells
31
Q

Acid fast bacteria

A
  • mycobacterium
  • cell wall contains a waxy lipid (mycolic acid) which is hard to stain
  • look gram positive in a gram stain
  • diseases like TB, leprosy (take a long time to grow and divide
32
Q

Acid fast stain

A
  1. Primary stain: Carbolfuschin (pink)
    - use heat to fix stain into cell wall
  2. Decolorizer: acid alcohol
    - wash pink color out of all cells that aren’t acid fast
  3. Counterstain: methylene blue
    Result: acid fast are pink, non acid fast are blue
33
Q

Negative stain

A
  • determined if cells have capsule (not stained by acidic or basic dye)
  • creates a white ring around stained cell
  • cells with capsule tend to be more virulent
34
Q

Flagellar stain

A

Coat flagella with a layer of dye or metal

35
Q

Endospore

A
  • clostridium and bacillus species

- Cell puts a copy of DNA into an endospore when it encounters harsh conditions (heat, lack of food)

36
Q

Schaeffer-Fulton stain

A
  1. Primary stain: malachite green
    - heat fix
  2. Decolorizer: water
    - washes out everything that isn’t a spire
  3. Counterstain: safranin (pink)
    Result: endospores are green, vegetative cells are pink

Microbiology (18 decks)

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