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Microbiology > Basic Bacteriology > Flashcards

Basic Bacteriology Flashcards

1
Q

general principles to consider in visualization

A
  • wavelength of radiation
  • magnification
  • resolution
  • contrast
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2
Q

______ act as waves with wavelengths dependent on the ____ of the electron beam

A

moving electrons, voltage

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3
Q

True or False

Radiation of smaller wavelengths results in enhanced microscopy

A

True

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4
Q

the apparent increase in size of an object, indicated by a number and the letter x

A

Magnification

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5
Q

How does magnification occur?

A

When a beam of radiation refracts as it passes through a lens

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6
Q

Analogy
Curved glass lenses: Light
Magnetic fields: _____

A

Electron beams

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7
Q

the ability of an instrument to distinguish between objects that are close together, as close as 0.2 µm

A

Resolution

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8
Q

resolution distance is dependent on ____

A
  • wavelength of light/electron beam

- numerical aperture of lens

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9
Q

modern microscopes use _____ wavelength radiation and lenses with ____ numerical apertures

A

Shorter, larger

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10
Q

the differences in intensity between two objects or between an object and its background

A

Contrast

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11
Q

How is contrast achieved?

A

Using stains

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12
Q

5 types of light microscopy

A
  1. Brightfield
  2. Darkfield
  3. Phase Contrast
  4. Confocal
  5. Fluorescent
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13
Q

the phenomenon wherein UV light causes specimens to radiate visible light

A

Fluorescence phenomenon

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14
Q

2 categories of staining under fluorescent microscopy

A
  • fluorochroming

- immunofluorescence/fluorescent antibody technique

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15
Q

the reaction between the fluorescent dye and the specimen (everything will be stained)

A

Fluorochroming

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16
Q

technique involving enhanced staining wherein the antibody binds to the fluorescent dye and only the part with the corresponding antigen is stained

A

Immunofluorescence

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17
Q

2 types of electron microscopy

A
  1. Transmission (TEM)

2. Scanning (SEM)

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18
Q

electron beams pass through the object and allows visualization of internal structures

A

Transmission (TEM)

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19
Q

electron beams scan the surface of objects and provide a 3D view of surface structures

A

Scanning (SEM)

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20
Q

2 ways by which bacteria can be examine

A
  • unstained, living state

- fixed, stained state

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21
Q

3 techniques to examine unstained, living bacteria

A
  1. Direct wet mount prep
  2. Hanging drop prep
  3. Intravital staining
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22
Q

preparation used to detect motile bacteria such as Campylobacter jejuni and Vibrio cholerae

A

Direct wet mount prep

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23
Q

microscopes used to view a direct wet mount prep of bacteria

A
  • dark field
  • phase contrast
  • light microscope w/ partially closed diaphragm (if previous 2 are unavailable)
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24
Q

differences between direct wet mount prep and hanging drop prep

A
  • morphology in hanging drop is less distorted

- motility in hanging drop is better appreciated

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25
Q

technique in examining unstained living bacteria using a diluted dye

A

Intravital staining

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26
Q

What should be done before fixing and staining bacteria?

A

Smear preparation

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27
Q

4 steps for fixed, stained state

A
  1. smear prep
  2. air-drying
  3. fixation
  4. staining
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28
Q

purpose of air-drying after smear prep

A
  • preserve bacterial morphology

- allow smear to adhere to slide

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29
Q

most common method of fixation

A

Heat fixation

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30
Q

How do you heat fix a slide?

A

Pass the slide with smear side up over a flame 3-5 times

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31
Q

fixative used during chemical fixation

A

Alcohol and formalin

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32
Q

3 types of staining

A
  • simple
  • differential
  • special
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33
Q

type of staining wherein a single dye is employed so that all the cells will have the same color

A

Simple staining

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34
Q

examples of simple stains

A
  • dilute carbol fuchsin

- methylene blue

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35
Q

2 types of simple staining

A
  • positive staining (stained spx)

- negative staining (stained bg)

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36
Q
  • type of staining wherein more than one dye is employed so that more than one color is observed
  • where contrast is most commonly observed
A

Differential staining

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37
Q

commonly used differential stains

A
  • Gram stain

- acid-fast stain

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38
Q

type of staining employed to isolate a structure of the bacterial cell so that it can be seen

A

Special staining

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39
Q

devised Gram staining

A

Dr. Hans Christian Gram

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40
Q

2 large groups divided by Gram stain and their colors

A

Gram (+) - deep-violet/purple

Gram (-) - pink/red

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41
Q

general rules for Gram (+) bacteria

A

All cocci are + except:

  • Neisseria grp.
  • Moraxella catarrhalis
  • Veillonella
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42
Q

general rules for Gram (-) bacteria

A

All bacilli are - except:

  • acid fast organisms (including Mycobacterium, Nocardia)
  • spore formers (Bacillus, Clostridium)
  • Corynebacterium sp.

Spiral organisms are also - when stained

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43
Q

primary stain in Gram staining

A

Crystal violet

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44
Q

mordant in Gram staining

A

Gram’s iodine

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45
Q

the large insolube complex formed after adding the mordant

A

Crystal violet iodine (CV) complex

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46
Q

When does differentiation start during Gram staining and acid fast staining?

A

In the decolorization step

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47
Q

decolorizer in Gram staining

A

Absolute alcohol or a mixture of acetone and alcohol

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48
Q

after decolorization, what happens to all gram (-) cells?

A

Become colorless

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49
Q

after decolorization, what happens to all gram (+) cells?

A

Remain violet

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50
Q

counterstain in Gram staining

A

Safranin

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51
Q

What does safranin do in Gram staining?

A

Give color to gram (-) cells

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52
Q

Steps in Gram staining (Hucker’s method)

A
  1. Smear
  2. Crystal violet
  3. Gram’s iodine
  4. Absolute alcohol
  5. Safranin

*washing is done in between steps and after the last step

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53
Q

3-step variation in Gram staining

A

Incorporate Safranin w/ Alcohol so that when the mixture is added, it will both decolorize and counterstain

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54
Q

3 bases on the principles behind Gram staining reaction

A
  1. composition of cell envelope
  2. presence of magnesium ribonucleate (protein complex)
  3. loss of cell wall integrity
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55
Q

explain the principle behind Gram staining based on cell envelope composition

A

Gram (+): cell wall has more proteins than lipids. Decolorizer coagulates proteins, thereby narrowing pore sizes, decreasing permeability, and trapping CVI complex in cells - retaining violet color.

Gram (-): cell wall has more lipids than proteins. Decolorizer dissolves lipids, thereby widening pore sizes, increasing permeability, and releasing CVI complex from cells - losing violet color.

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56
Q

What is the substance responsible for an organism’s gram positiveness?

A

Magnesium ribonucleate

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57
Q

What causes the loss of cell wall integrity?

A
  • old age
  • action of autolytic enzymes
  • antibiotic treatment
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58
Q

meaning of ‘acid fast’ organisms

A

organisms with long chains of fatty acids in cell walls that make them resistant to decolorization by acid alcohol

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59
Q

What is the substance responsible for the acid fastness of an organism?

A

Long chain mycolic acids

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60
Q

2 methods of staining acid fast organisms

A
  1. Ziehl-Neelsen

2. Cold Kinyoun

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61
Q

primary stain in acid fast staining

A

Carbol fuchsin (red)

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62
Q

decolorizer in acid fast staining

A

Acid alcohol

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63
Q

counterstain in acid fast staining

A

Methylene blue

64
Q

Steps in Acid fast staining

A
  1. Smear
  2. Carbol fuchsin
  3. Acid alcohol
  4. Methylene blue
65
Q

Which stain colors organisms with long chain mycolic acids in acid fast staining?

A

Carbol fuchsin

66
Q

Which stain colors organisms without long chain mycolic acids in acid fast staining?

A

Methylene blue

67
Q

end result or colors after acid fast staining

A

acid fast - red

non-acid fast - blue

68
Q

composition of gram (+) cell envelope

A
  • variable capsule
  • thick peptidoglycan (cell wall)
  • cytoplasmic membrane
69
Q

composition of gram (-) cell envelope

A
  • variable capsule
  • outer membrane
  • single planar sheet of peptidoglycan (cell wall)
  • cytoplasmic membrane (inner membrane/plasma membrane)
70
Q

a gelatinous, sticky substance surrounding the cell

A

Glycocalyx

71
Q

When is the glycocalyx called a capsule?

A

When it is made up of organized, repeating units of organic chemicals firmly attached to the cell surface (forming another or a definite cell layer)

72
Q

examples of organisms with the glycocalyx as capsule

A 
▪ Streptococcus pneumoniae
▪ Klebsiella pneumoniae
▪ Haemophilus influenzae
▪ Bacillus anthracis
▪ Clostridium perfringens
73
Q

When is the glycocalyx called a slime layer?

A

When it is loose and water soluble

74
Q

examples of organisms with the glycocalyx as slime layer

A

▪ Sarcina lutea

▪ Bacteroides sp.

75
Q

significance of the presence of capsule or slime layer

A
  • protect the cell from desiccation
  • presence of glycocalyx is a feature of many pathogenic prokaryotes
  • plays a role in organisms’ ability to survive & cause disease
  • capsule is antigenic
76
Q

Which layer of the outer membrane is known as the endotoxin of gram (-) bacteria? Why is it called as such?

A

the lipopolysaccharide (LPS) layer (specifically lipid A) because it is released only when the gram (-) bacteria is destroyed which causes:

  • fever
  • vasodilation
  • inflammation
  • shock
  • blood clotting
77
Q

Which portion of LPS is antigenic?

A

Polysaccharide (somatic or O antigen)

78
Q

significance of outer membrane of gram (-) bacteria

A
  • has surface antigens
  • has phage receptors (porins)
  • it is a selective permeability barrier
79
Q

part of the cell envelope which provides structure and shape to the cell, acts as a barrier, and protects the cell from osmotic lysis

A

Cell wall

80
Q

composition of peptidoglycan in bacterial cell wall

A

Peptido portion: amino acids

Glycan portion: 2 regularly, alternating sugars

  • NAG (N-acetylglucosamine)
  • NAM (N-acetylmuramic acid)
81
Q

What is formed when layers of peptidoglycan sheets enclose the organism where each layer is cross-linked to each other by amino acids?

A

Murein sacculus

82
Q

composition of gram (+) cell wall

A
  • teichoic acids
  • lipoteichoic acids
  • cell wall associated proteins
83
Q

What anchors the cell wall to the next layer in gram (+) bacteria?

A

Lipoteichoic acids

84
Q

What anchors the outer membrane to the cell wall in gram (-) bacteria?

A

Lipoprotein layer

85
Q

major surface antigens of gram (+) cells

A
  • teichoic acids

- cell wall associated proteins

86
Q

How can the cell wall be removed?

A

Using hypertonic solution of sucrose or salts

87
Q

if the source of the wall is an osmotically sensitive organism and is a gram (+) cell, it is called a ___

A

Protoplast

88
Q

if the remnants of the outer membrane are found on the wall as an osmotically sensitive organism and is a gram (-) cell, it is called a ___

A

Spheroplast

89
Q

organism that is naturally occurring without a cell wall

A

Mycoplasma pneumoniae

90
Q

cell wall that contains a variety of specialized polysaccharides and proteins but no peptidoglycan

A

Archaeal cell wall

91
Q

major properties of cell wall

A
  • protection from osmotic lysis
  • rigidity and shape to cell
  • major surface antigens of gram (+) cells
  • support for propulsion of flagella
92
Q

located between cell membrane and outer membrane, found only in gram (-) bacteria, and contains the peptidoglycan and periplasm

A

Periplasmic space

93
Q

a gel-like substance containing water, nutrients, and secretions of the cell involved in specific transport

A

Periplasm

94
Q

functions of the cell membrane

A
  • transport solutes in/out of cell
  • housing enzymes involved in OM and CW synthesis, assembly & secretion of extracytoplasmic & extracellylar substances
  • generation of chemical energy
  • mediation of chromosomal segregation during replication
  • housing molecular sensors that monitor chemical and physical changes in environment
95
Q

long, whiplike structures extending beyond the surface of the cell and glycocalyx and propel the cell through the environment

A

Flagellum

96
Q

flagellar antigen

A

H (Hauch) antigen

97
Q

role of mordant when staining the flagellum

A

Increases the parameter of the filament (thicken) so when stained, it can be easily visualized

98
Q

3 parts of the flagellum

A
  • long thin filament
  • hook
  • basal body
99
Q

composition of the flagellum’s filament

A

Many identical globular protein molecules (flagellin)

100
Q

a curved structure where the base of the flagellum’s filament is inserted

A

Hook

101
Q

anchors the filament and hook to the CW by a rod and a series of 2 or 4 rings

A

Basal body

102
Q

True or False

The hook, rod, and rings of the flagellum allow the filament to rotate 360°

A

True

103
Q

5 flagellar arrangements based on Messea’s classification

A
  1. monotrichous
  2. lophotrichous
  3. amphitrichous
  4. peritrichous
  5. atrichous
104
Q

a single, polar flagellum

A

Monotrichous

105
Q

examples of organisms w/ monotrichous flagellum

A
  • Vibrio cholerae
  • Campylobacter jejuni
  • Pseudomonas aeruginosa
106
Q

cells with a tuft of flagella on only one end

A

Lophotrichous

107
Q

examples of organisms w/ lophotrichous flagella

A

Pseudomonas spp other than P. aeruginosa

108
Q

both ends contain either a single flagellum or a tuft of flagella

A

Amphitrichous

109
Q

examples of organisms w/ amphitrichous flagella

A

Pseudomonas spp other than P. aeruginosa

110
Q

flagella is found all over the cell surface

A

Peritrichous

111
Q

examples of organisms w/ peritrichous flagella

A 
Salmonella typhi (agent of typhoid fever)
 Proteus vulgaris
112
Q

not flagellated organisms

A

Atrichous

113
Q

examples of organisms w/ atrichous flagella

A

Shigella dysenteriae (agent of bacilliary
dysentery)
Klebsiella pneumoniae

114
Q

Some spiral bacteria have _____ flagella that spiral tightly around the cell instead of protruding into the environment

A

Amphitrichous

115
Q

When are flagella considered as endoflagella?

A

When they form an axial filament that wraps around the cell between the cell membrane and the outer membrane (periplasmic space)

116
Q

examples of organisms w/ endoflagella

A

Spirochetes

117
Q

functions of the flagella

A
  • motility of the cell
  • useful in ID of bacteria
  • allow classification of prokaryotes into strains called serovars
118
Q

What do you call it when flagellated bacteria change the antigenic type of its flagella?

A

Phase variation

119
Q

sticky, proteinaceous, bristle-like projections used by gram (-) bacteria to adhere to one another and to substances in the environment

A

Fimbriae

120
Q

example of an organism with fimbriae

A

Neisseria gonorrhoeae

121
Q

tubules composed of a protein called pilin

A

Pilus/Pili

122
Q

a type of pili that mediate the transfer of DNA from one cell to another

A

Sex/conjugal pili

123
Q

importance of microfibrils (fimbriae & pili)

A
  • allow cells to adhere to host cells (adhesins)
  • allow cells to adhere to host cells containing sugar (lectins)
  • conduit for DNA passage
  • surface translocation
124
Q

a membrane-associated cytoplasmic sac containing lamellar, tubular, or vseicular structures

A

Mesosome

125
Q

2 types of mesosomes

A
  • septal (DNA replication & cell division)

- lateral (secretion)

126
Q

highly coiled DNA intermixed with RNA, polyamines, and various proteins

A

Nucleoid

127
Q

functions of nucleoid

A
  • houses info for bacterial functions

- directs synthesis of cellular products

128
Q

small, roughly spherical cytoplasmic particles made up of 30% proteins and 70% RNA

A

Ribosomes

129
Q

function of ribosomes

A

Protein synthesis

130
Q

food reserves or storage granules also known as inclusion bodies

A

Cytoplasmic granules

131
Q

2 types of cytoplasmic granules

A
  • glycogen (glucose)

- polyphosphate granules (inorganic phosphates)

132
Q

other names of polyphosphate granules

A
  • metachromatic granules
  • volutin granules
  • Babes-Ernst granules
133
Q

examples of organisms with polyphosphate granules

A
  • Mycobacterium tuberculosis (agent of TB)
  • Corynebacterium diphtheriae (agent of
    diphtheria)
  • Yersinia pestis (agent of plague)
134
Q

importance of cytoplasmic granules

A
  • taxonomy as not all bacteria contain these granules
135
Q

How are endospores formed?

A

By sporulation

136
Q

When does sporulation occur?

A
  • when there is a scarcity of food

- when the spore-former encounters unfavorable environmental conditions

137
Q

2 genera producing spores

A
  • aerobic Genus Bacillus

- anaerobic Genus Clostridium

138
Q

the process of restoring the vegetative bacteria

A

Germination

139
Q

What substance makes spores resistant to adverse environmental conditions?

A

Calcium dipicolinate

140
Q

3 classification of spores based on location

A
  • central
  • subterminal
  • terminal
141
Q

How would you know if the spore is centrally located in the cell?

A

If there are equal amounts of stained cytoplasm on both sides of the spore

142
Q

How would you know if the spore is subterminally located in the cell?

A

If there are unequal amounts of stained cytoplasm on both sides of the spore

143
Q

How would you know if the spore is terminally located in the cell?

A

If all the stained cytoplasm is only on one side of the spore

144
Q

importance of the presence of spores

A
  • taxonomy: helps in identifying the organism

- clinical: helps in sterilization

145
Q

organism with a large terminal spore that is wider than the bacterial cell, giving it a drumstick appearance

A

Clostridium tetani

146
Q

small, circular, double-stranded pieces of DNA

A

Plasmids

147
Q

True or False

The presence of plasmids in bacterial cells is essential to the viability of the organism

A

False, not essential

148
Q

4 types of plasmids

A
  1. F (fertility) factor
  2. R (resistance) factor
  3. Colicinogenic plasmid
  4. Virulence plasmid
149
Q

plasmid which provided for the discovery of bacterial sexuality

A

F factor

150
Q

cells with F factor considered as males/donors

A

F+ cells

151
Q

cells with F factor considered as females/recipients

A

F- cells

152
Q

when cells have this factor, it can convert the entire cell population to become antibiotic resistant

A

R factor

153
Q

plasmid that contains genes that code for synthesis of bactericidal proteins

A

Colicinogenic plasmid

154
Q

Bactericidal proteins are called ____

A

Colicines

155
Q

plasmid that contains genes that will code for toxin production

A

Virulence plasmid

Microbiology (4 decks)

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