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Microbiology Exam 1 (Modules 1&2) > Chapter 2 > Flashcards

Chapter 2 Flashcards

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Biology 101 flashcards
1
Q

Aims of the examiner when observing specimen

A

Observation of:

  • overall structure
  • identification
  • any movement?
  • thicker or thinner specimen
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2
Q

Wet mounds

A

consists of a drop or two of culture placed on a slide and overlaid with a coverslip

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3
Q

Hanging Drop

A
  • a drop of culture is placed in a concave (depression slide)
  • Vaseline adhesive or sealant, and coverslip are used to suspend the sample
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4
Q

When using wet mounds or hanging drops to observe specimens, cells are suspended in what substances to maintain viability and to help see them move as they naturally would

A

water, broth, or saline

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5
Q

Procedure that applies colored chemical dyes to specimens

A

Staining

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6
Q

Basic dyes have a ______ charge

A

positive +

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7
Q

Acidic dyes have a _____ charge

A

negative -

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8
Q

Bacteria have numerous negatively charged substances and ______ basic dyes

A

attract (because basic dyes are positive)

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9
Q

Cells ____ acidic dyes

A

repel

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10
Q

Positive stains

A

dye sticks to specimen and gives it color

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11
Q

Negative stains

A

Dye does not stick to the specimen but settles some distance from its outer boundary forming a silhouette

; can be used to accentuate a capsule
; Nigrosin/India Ink is a negative stain

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12
Q

Simple stains

A

only require a single dye and are used for uncomplicated procedures

  • cause all cells in the smear to turn more or less the same color
  • reveal shape, size, and arrangement
  • positive type of staining
  • won’t help differentiate between cells
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13
Q

Differential stains

A
  • utilizes two differently colored dyes: a primary dye and counterstain
  • distinguish cells types or parts (especially CELL WALL)
  • requires additional chemical reagents to produce the desired reaction
  • developed in 1884 by Hans Christian Gram: THE GRAM STAIN
  1. Crystal Positive (primary dye)
  2. Gram’s Iodine (stabilizer/mordant)
  3. Alcohol Rinse (wash/cleanse)
  4. Safranin (counterstain)
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14
Q

The Gram Stain (differential stain)

A

remains the universal basis for bacterial classification and identification

a practical aid in diagnosing infection and guiding treatment

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15
Q

Differential Stains: Acid-Fast Stain

A

differentiates acid-fast bacteria (acid resistant - turns pink) from non acid-fast bacteria (non acid resistant - turns blue)

*originated as a method to detect mycobacterium tuberculosis

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16
Q

Differential Stain: The Endospore stain

A

similar to acid-fast stain in that dye is forced by heat into resistant bodies called endospores

  • distinguishes between endospores and vegetative (inactive) cells
  • significant in identifying gram-positive, spore-forming members of the genus Bacillus and Clostridium
17
Q

Special Stains

A

used to emphasize cell parts that are not revealed by conventional staining methods

18
Q

Special Stains: Capsular Staining

A

observes microbial capsules

-negatively stained with India ink

19
Q

Special Stains: Flagellar staining

A

used to reveal tiny slender filaments used by bacteria for locomotion

-flagella are enlarged by depositing a coating on the outside of the filament and then staining it

20
Q

Outcome: List and describe the three elements of good microscopy.

A

Magnification: occurs in two phases, the real image (slide) and the virtual image (what we see through lens)
-oil immersion total mag: 1000x

Resolution: resolving power; the capacity of an optical system to distinguish two adjacent objects or points from one another

  • resolution oh human eye: 0.2mm
  • Res. of oil immersion lens: 0.2 micrometers

Contrast: darkness of the background relative to the specimen placed on the stage
-measured in refractive index; the degree of bending that light undergoes as it passes from one medium to another

21
Q

Outcome:

Differentiate between light and electron microscopy

A

Light:

  • uses light as an illuminating source
  • lower resolution
  • colored image

Electron:

  • used electron beam as illuminating source
  • higher resolution
  • black and white imaging
22
Q

Outcome:

Convert among different units of metric system

A

1 micrometer = 1000 nanometers

1000 micrometers = 1 millimeter

23
Q

Outcome: Give an example of a SIMPLE stain

A

A crystal violet stain

A methylene blue stain

24
Q

Outcome: Give an example of a DIFFERENTIAL stain

A

Gram stain (gram pos turns purple and gram neg turns pink)

Acid-fast stain

Endospore stain

25
Q

Outcome: Give an example of a SPECIAL stain

A

A flagellar stain

A capsular stain with India Ink

26
Q

Outcome: Explain what the 5 I’s are and what each step entails

A
  1. Inoculation
    -infection
    -introduction of an inoculum (small sample of microbes) to a medium
  2. Incubation
    -applying special needs of the microbes to grow
    -ie. keeping certain temperatures or introducing different gases like oxygen to help the microbes grow
    3.

Microbiology Exam 1 (Modules 1&2) (9 decks)

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