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microbiology > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

a microscope has only one lens

A

a simple microscope

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2
Q

Ocular lens magnify the specimen ______ times.

A

X10

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3
Q

There are _____ objective lenses

Total magnification of a specimen = objective lens  ocular lens

A

4

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4
Q
  • scanning magnification
A

x4

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5
Q
  • low power
A

x10

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6
Q
  • high power
A

x 40

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7
Q
  • oil immersion
A

x100

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8
Q

Total magnification of a specimen =

A

objective lens X ocular lens

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9
Q

the ability of the lenses to distinguish two points

A

resolution

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10
Q

_________ wavelengths of light provide greater resolution

A

shorter

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11
Q

Resolution =

A 
wave length (535 nm)  divided by              
 	2 x numerical apperture
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12
Q

the light-bending ability of a medium.

A

refractive index

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13
Q

is used to keep light from bending

A

Immersion oil

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14
Q

Glass and immersion oil has the same refractive index.

A

The light may bend in air so much that it misses the 100 x magnification lens

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15
Q

Uses UV light.
Fluorescent substances absorb UV light and emit visible light.
Cells may be stained with fluorescent dyes (fluorochromes).

A

Fluorescence Microscopy

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16
Q

What Uses electrons instead of light.
The shorter wavelength of electrons gives greater resolution.
Light passes through specimen, then an electromagnetic lens, to a screen or film.
Specimens may be stained with heavy metal salts.

A

Electron Microscopy

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17
Q

Transmission Electron Microscopy (TEM)

10,000-100,000; resolution 2.5 nm

A

`

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18
Q

Scanning Electron Microscopy (SEM)

1000-10,000; resolution 20 nm

A

`

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19
Q

A thin film of a solution of microbes on a slide is a ______

A

smear

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20
Q

A smear is usually ______ to attach the microbes to the slide and to kill the microbes.

A

fixed

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21
Q

Stains consist of a _______ & _____ ion

A

positive & negative

22
Q

In a _____ dye, the chromophore is a cation

A

basic

23
Q

In an _______ dye, the chromophore is an anion

A

acidic

24
Q

Bacteria are slightly ______charged at pH 7

A

negatively

25
Q

More basic dyes are used to stain bacteria, since the cells are _____ charged and the dye has a ______ charged chromophore

A

negatively charged; positively charged

26
Q

Staining the background instead of the cell is called _________ _________

A

negative staining

27
Q

_______ dyes are used in negative staining.

A

acidic

28
Q

__________ charged bacterial cells repel the negatively charged dye staining the background instead of the cells.

A

negatively

29
Q

Use of a single basic dye is called a _____stain; used to stain any bacteria

A

simple

30
Q

________ Stains are used to identify different types of bacteria

gram stain, acid-fast stain

A

differential

31
Q

_____ stains/______ stains: use to identify different bacterial structures.

ex- capsule stain, endospore stain, flagella stain

A

special; structural

32
Q

The Gram stain classifies bacteria into gram-_____ and gram-_____.

A

positive and negative

33
Q

Gram-______ bacteria tend to be killed by penicillin and detergents.

A

positive

34
Q

Gram-______ bacteria are more resistant to antibiotics.

A

negative

35
Q

A gram stain includes what 4 things?

A

includes a primary stain, mordant, decolorizing agent and a secondary or counter stain.

36
Q

A _____is used to hold the stain

A

mordant

37
Q

gram stains- Primary stain: crystal violet turns what color for
Gram + cells and what color for Gram - cells?

A

+ purple

- purple

38
Q

gram stains- Mordant Iodine turns gram + what color? gram - what color?

A

+ purple

- purple

39
Q

gram stains- Decolorizing agent:

Alcohol-acetone turns gram + what or

A

+ purple

-colorless

40
Q

gram stain- Counterstain:

Safranin

A

+ purple

- red

41
Q

most of the bacterial cultures we use in the lab are ____ cultures. Agar slants are used to grow and maintain ___ cultures. Also, bacterial cells in a ____ culture will have the same shape or morphology

A

pure

42
Q

This can be a contamination due to bad aseptic technique. Usually, bacterial cells in a ____ culture will have different shapes or morphology

A

mixed culture

43
Q

Gram stain works better when ____ bacterial cultures (cells that are less than _____ old) are used.

A

young; 24 hours

44
Q

When gram positive bacterial cells get ____, their peptidoglycan layer in the cell wall start to _____ ____, not being able to retain the primary stain as well as younger cells. These cells can get decolorized and then take the secondary stain in.

A

old; break down

45
Q

Cells that retain a ____ stain in the presence of acid-alcohol are called acid-fast.

A

basic

46
Q

______ fast cells lose the basic stain when rinsed with acid-alcohol, and are usually counterstained (with a different color basic stain) to see them.

A

non-acid

47
Q

acid- fast stain-
Primary stain:
Carbolfuchsin

turns acid- fast cells what color?
turns other cells what color?

A

acid- fast: Dark red

other cells: dark red

48
Q

acid- fast stain-
Decolorizing agent:
Acid-alcohol

turns acid- fast cells what color?
turns other cells what color?

A

acid- fast: Dark red

other cells: colorless

49
Q

acid- fast stain-
Counterstain:
Methylene blue

turns acid- fast cells what color?
turns other cells what color?

A

acid- fast: Dark red

other cells: Blue

50
Q

____ staining and _____ staining is useful for capsules.

A

negative; simple

51
Q

_____ is required to drive a stain into endospores.

A

heat

52
Q

_____ staining requires a mordant to make the flagella wide enough to see.

A

Flagella

microbiology (7 decks)

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