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V. Micro 151 > 3 Demonstration of Microorganisms > Flashcards

3 Demonstration of Microorganisms Flashcards

1
Q

Approximate size ranges for Bacteria: (4)

A
  1. Typical Bacteria - range 0.5-5 um, length 1-10 um
  2. Cocci (Spherical Bacteria) - diameter 0.5-2 um
  3. Bacilli (Rod-Shaped Bacteria) - diameter 0.5-1 um, length 2-10 um
  4. Spiral and Helical Bacteria - similar to typical bacteria
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2
Q
  1. Similar to bacteria, these cells can vary widely in size (from 0.1 μm to over 15 μm).
  2. Some extremophiles, such as those found in hot springs and deep-sea hydrothermal vents, can have unique shapes(e.g., spherical (cocci), rod-shaped (bacilli), spiral, and even flat or square forms - e.g., Haloquadratum walsbyi) and sizes to adapt to their environments.
A

Archaea

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3
Q

Bacterial Shapes:
* Coccus –
* Bacillus –
* Spiral
* Vibrio –
* Spirochete -

A

round

rod

spiral

comma shaped

helical

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4
Q

six common shapes of bacteria:

A

✔ coccus (meaning “berry”)
✔Bacillus/ rod-shaped (meaning “little staff”)
✔Coccobacillus
✔Vibrio
✔Spirochete
✔spirillum

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5
Q

several arrangements of these cells:

A

✔single, chains (strepto-)
✔clusters (staphylo-)
✔pairs (diplo-)

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6
Q
  • the term for when Most bacteria exhibit only one shape
A

MONOMORPHIC

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7
Q

Some bacteria can exhibit many shapes
e.g - Members of genus Corynebacterium

A

PLEOMORPHIC/POLYMORPHIC

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8
Q

TYPES OF FIXATION

A
  1. Heat-fixation
  2. Chemical fixation
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9
Q
  • gently flame (heating) an air-dried film of bacteria
  • preserve over all morphology but not structures within the cell
A

Heat-fixation

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10
Q
  • used to protect fine cellular substructures and the morphology of larger, more delicate microorganisms
A

Chemical fixation

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11
Q

2 types of dyes for staining

A

basic dyes (+charge/cationic)

acid dyes (- charge/anionic)

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12
Q

e.g., methylene blue, basic fuchsin, crystal violet, safranin, malachite green
* most often used in bacteriology
* bind to negatively charged molecules: nucleic acids and proteins; certain organelles

A

basic dyes (+charge/cationic)

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13
Q
  • e.g., eosin, rose bengal, and acid fuchsin
  • with carboxyls (-COOH) and phenolic hydroxyls (-OH);
  • bind to positively charged cell structures e.g., Histones; cytoplasmic proteins; collagen
A

acid dyes (- charge/anionic)

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14
Q
  • process of applying colored substances, known as stains or dyes, to microbial cells
    or structures to enhance their visibility under a microscope
A

Staining

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15
Q
  • is a substance that adheres to a cell, giving the cell color.
  • The presence of color gives the cells significant contrast so are much more visible.
  • Different stains have different affinities for different organisms, or different parts of organisms
A

Stain

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16
Q
  • Simple, easy to use; single staining agent used; using basic and acid dyes.
  • Features of dyes: give coloring of microorganisms; bind specifically to various cell structures.
  • involves the application of a single stain solution to a fixed smear
  • simple and easy
  • Crystal Violet, Methylene Blue, CF (commonly used basic dyes) – determine shape, size and arrangement of bacteria
A

Simple Staining

17
Q
  • To distinguish different kinds of bacteria into separate groups based on staining properties.
    -Two types: Gram stain & Acid-fast stain.

divide bacteria into separate groups based on staining properties
-Gram Stain – developed by Hans Christian Gram in 1884
-Crystal violet-iodine-acetone or alcoholsafranin (CIAS)

A

Differential Staining

18
Q

-are designed to visualize specific structures or types of bacteria that are not easily seen with basic stains like the Gram stain.
-These stains can highlight specific features like capsules, spores, flagella,

A

Special Staining

19
Q

*Differential stain

  • lose crystal violet and
    stain red from safranin
    counterstain
A

Gram-negative

20
Q

*Differential stain

  • retain crystal violet and
    stain purple
A

Gram-positive

21
Q
  • Important basis of bacterial classification and identification
  • Practical aid in diagnosing infection and guiding drug treatment

-which divides most clinically significant bacteria into two main groups, is the first step in bacterial identification.

A

The Gram Stain

22
Q

Bacteria stained purple/blue are Gram ____ - their cell walls have thick petidoglycan and teichoic acid.

A

Gram +

23
Q

Bacteria stained red/pink are Gram ____ their cell walls have have thin peptidoglycan and lipopolysaccharides with no ____.

A

Gram –

teichoic acid

24
Q

Components of acid-fast staining

A
  • Primary Stain: Strong carbol fuchsin, which is basic fuchsin dissolved in phenol.
  • Decolorizer: a solution of 20% sulfuric acid (H₂SO₄) or acid-alcohol.
  • Counterstain: Loeffler’s methylene blue or malachite green, used to stain the background and non-acid-fast bacteria
25
Q
  • reveals the presence of diffuse capsules surrounding many bacteria
  • ink and dye cannot penetrate the bacterial cell or its capsule
  • E.g., Klebsiella pneumoniae
  • bacteria are mixed with India ink or Nigrosin dye
  • air drying
  • bacteria appear lighter bodies with blue black background
A

Negative staining

26
Q

type of stain
* * for genus Bacillus and Clostridium Other genera: Desulfotomaculum, Sporosarcina, Sporolactobacillus, Oscillospira,
Thermoactinomyces
* uses the Schaeffer-Fulton Method

A

Endospore (Spore) staining

27
Q

*Schaeffer-Fulton Procedure (5)

A
  1. Preparation of a Bacterial Smear-Air dry
  2. Application of Primary Dye (Malachite Green) w/ concurrent application of heat
  3. Allow slide to cool
  4. Rinse w/ water
  5. Application of Counterstain (Safranin) - green endospore resting in a pink to red cell
28
Q
  • Uses mordant and
    carbolfuchsin stain to
    increase flagellar
    diameter until resolved
    by light microscope
A

Flagellar Stain

29
Q
  • provides information and location of flagella
  • to observe bacterial flagella with a light microscope, thickness of flagella is increased by coating with mordants like tannic acid and potassium alum and stained with pararosaniline (Leifson method) or basic fuchsin (Gray method)
A

Flagellar Staining

V. Micro 151 (10 decks)

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