Basic Bacteriology Flashcards
(155 cards)
1
Q
general principles to consider in visualization
A
- wavelength of radiation
- magnification
- resolution
- contrast
2
Q
______ act as waves with wavelengths dependent on the ____ of the electron beam
A
moving electrons, voltage
3
Q
True or False
Radiation of smaller wavelengths results in enhanced microscopy
A
True
4
Q
the apparent increase in size of an object, indicated by a number and the letter x
A
Magnification
5
Q
How does magnification occur?
A
When a beam of radiation refracts as it passes through a lens
6
Q
Analogy
Curved glass lenses: Light
Magnetic fields: _____
A
Electron beams
7
Q
the ability of an instrument to distinguish between objects that are close together, as close as 0.2 µm
A
Resolution
8
Q
resolution distance is dependent on ____
A
- wavelength of light/electron beam
- numerical aperture of lens
9
Q
modern microscopes use _____ wavelength radiation and lenses with ____ numerical apertures
A
Shorter, larger
10
Q
the differences in intensity between two objects or between an object and its background
A
Contrast
11
Q
How is contrast achieved?
A
Using stains
12
Q
5 types of light microscopy
A
- Brightfield
- Darkfield
- Phase Contrast
- Confocal
- Fluorescent
13
Q
the phenomenon wherein UV light causes specimens to radiate visible light
A
Fluorescence phenomenon
14
Q
2 categories of staining under fluorescent microscopy
A
- fluorochroming
- immunofluorescence/fluorescent antibody technique
15
Q
the reaction between the fluorescent dye and the specimen (everything will be stained)
A
Fluorochroming
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
17
Q
2 types of electron microscopy
A
- Transmission (TEM)
2. Scanning (SEM)
18
Q
electron beams pass through the object and allows visualization of internal structures
A
Transmission (TEM)
19
Q
electron beams scan the surface of objects and provide a 3D view of surface structures
A
Scanning (SEM)
20
Q
2 ways by which bacteria can be examine
A
- unstained, living state
- fixed, stained state
21
Q
3 techniques to examine unstained, living bacteria
A
- Direct wet mount prep
- Hanging drop prep
- Intravital staining
22
Q
preparation used to detect motile bacteria such as Campylobacter jejuni and Vibrio cholerae
A
Direct wet mount prep
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)
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
25
technique in examining unstained living bacteria using a diluted dye
Intravital staining
26
What should be done before fixing and staining bacteria?
Smear preparation
27
4 steps for fixed, stained state
1. smear prep
2. air-drying
3. fixation
4. staining
28
purpose of air-drying after smear prep
- preserve bacterial morphology
| - allow smear to adhere to slide
29
most common method of fixation
Heat fixation
30
How do you heat fix a slide?
Pass the slide with smear side up over a flame 3-5 times
31
fixative used during chemical fixation
Alcohol and formalin
32
3 types of staining
- simple
- differential
- special
33
type of staining wherein a single dye is employed so that all the cells will have the same color
Simple staining
34
examples of simple stains
- dilute carbol fuchsin
| - methylene blue
35
2 types of simple staining
- positive staining (stained spx)
| - negative staining (stained bg)
36
- type of staining wherein more than one dye is employed so that more than one color is observed
- where contrast is most commonly observed
Differential staining
37
commonly used differential stains
- Gram stain
| - acid-fast stain
38
type of staining employed to isolate a structure of the bacterial cell so that it can be seen
Special staining
39
devised Gram staining
Dr. Hans Christian Gram
40
2 large groups divided by Gram stain and their colors
Gram (+) - deep-violet/purple
| Gram (-) - pink/red
41
general rules for Gram (+) bacteria
All cocci are + except:
- Neisseria grp.
- Moraxella catarrhalis
- Veillonella
42
general rules for Gram (-) bacteria
All bacilli are - except:
- acid fast organisms (including Mycobacterium, Nocardia)
- spore formers (Bacillus, Clostridium)
- Corynebacterium sp.
Spiral organisms are also - when stained
43
primary stain in Gram staining
Crystal violet
44
mordant in Gram staining
Gram's iodine
45
the large insolube complex formed after adding the mordant
Crystal violet iodine (CV) complex
46
When does differentiation start during Gram staining and acid fast staining?
In the decolorization step
47
decolorizer in Gram staining
Absolute alcohol or a mixture of acetone and alcohol
48
after decolorization, what happens to all gram (-) cells?
Become colorless
49
after decolorization, what happens to all gram (+) cells?
Remain violet
50
counterstain in Gram staining
Safranin
51
What does safranin do in Gram staining?
Give color to gram (-) cells
52
Steps in Gram staining (Hucker's method)
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
53
3-step variation in Gram staining
Incorporate Safranin w/ Alcohol so that when the mixture is added, it will both decolorize and counterstain
54
3 bases on the principles behind Gram staining reaction
1. composition of cell envelope
2. presence of magnesium ribonucleate (protein complex)
3. loss of cell wall integrity
55
explain the principle behind Gram staining based on cell envelope composition
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.
56
What is the substance responsible for an organism's gram positiveness?
Magnesium ribonucleate
57
What causes the loss of cell wall integrity?
- old age
- action of autolytic enzymes
- antibiotic treatment
58
meaning of 'acid fast' organisms
organisms with long chains of fatty acids in cell walls that make them resistant to decolorization by acid alcohol
59
What is the substance responsible for the acid fastness of an organism?
Long chain mycolic acids
60
2 methods of staining acid fast organisms
1. Ziehl-Neelsen
| 2. Cold Kinyoun
61
primary stain in acid fast staining
Carbol fuchsin (red)
62
decolorizer in acid fast staining
Acid alcohol
63
counterstain in acid fast staining
Methylene blue
64
Steps in Acid fast staining
1. Smear
2. Carbol fuchsin
3. Acid alcohol
4. Methylene blue
65
Which stain colors organisms with long chain mycolic acids in acid fast staining?
Carbol fuchsin
66
Which stain colors organisms without long chain mycolic acids in acid fast staining?
Methylene blue
67
end result or colors after acid fast staining
acid fast - red
| non-acid fast - blue
68
composition of gram (+) cell envelope
- variable capsule
- thick peptidoglycan (cell wall)
- cytoplasmic membrane
69
composition of gram (-) cell envelope
- variable capsule
- outer membrane
- single planar sheet of peptidoglycan (cell wall)
- cytoplasmic membrane (inner membrane/plasma membrane)
70
a gelatinous, sticky substance surrounding the cell
Glycocalyx
71
When is the glycocalyx called a capsule?
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
examples of organisms with the glycocalyx as capsule
```
▪ Streptococcus pneumoniae
▪ Klebsiella pneumoniae
▪ Haemophilus influenzae
▪ Bacillus anthracis
▪ Clostridium perfringens
```
73
When is the glycocalyx called a slime layer?
When it is loose and water soluble
74
examples of organisms with the glycocalyx as slime layer
▪ Sarcina lutea
| ▪ Bacteroides sp.
75
significance of the presence of capsule or slime layer
- 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
Which layer of the outer membrane is known as the endotoxin of gram (-) bacteria? Why is it called as such?
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
Which portion of LPS is antigenic?
Polysaccharide (somatic or O antigen)
78
significance of outer membrane of gram (-) bacteria
- has surface antigens
- has phage receptors (porins)
- it is a selective permeability barrier
79
part of the cell envelope which provides structure and shape to the cell, acts as a barrier, and protects the cell from osmotic lysis
Cell wall
80
composition of peptidoglycan in bacterial cell wall
Peptido portion: amino acids
Glycan portion: 2 regularly, alternating sugars
- NAG (N-acetylglucosamine)
- NAM (N-acetylmuramic acid)
81
What is formed when layers of peptidoglycan sheets enclose the organism where each layer is cross-linked to each other by amino acids?
Murein sacculus
82
composition of gram (+) cell wall
- teichoic acids
- lipoteichoic acids
- cell wall associated proteins
83
What anchors the cell wall to the next layer in gram (+) bacteria?
Lipoteichoic acids
84
What anchors the outer membrane to the cell wall in gram (-) bacteria?
Lipoprotein layer
85
major surface antigens of gram (+) cells
- teichoic acids
| - cell wall associated proteins
86
How can the cell wall be removed?
Using hypertonic solution of sucrose or salts
87
if the source of the wall is an osmotically sensitive organism and is a gram (+) cell, it is called a ___
Protoplast
88
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 ___
Spheroplast
89
organism that is naturally occurring without a cell wall
Mycoplasma pneumoniae
90
cell wall that contains a variety of specialized polysaccharides and proteins but no peptidoglycan
Archaeal cell wall
91
major properties of cell wall
- protection from osmotic lysis
- rigidity and shape to cell
- major surface antigens of gram (+) cells
- support for propulsion of flagella
92
located between cell membrane and outer membrane, found only in gram (-) bacteria, and contains the peptidoglycan and periplasm
Periplasmic space
93
a gel-like substance containing water, nutrients, and secretions of the cell involved in specific transport
Periplasm
94
functions of the cell membrane
- 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
long, whiplike structures extending beyond the surface of the cell and glycocalyx and propel the cell through the environment
Flagellum
96
flagellar antigen
H (Hauch) antigen
97
role of mordant when staining the flagellum
Increases the parameter of the filament (thicken) so when stained, it can be easily visualized
98
3 parts of the flagellum
- long thin filament
- hook
- basal body
99
composition of the flagellum's filament
Many identical globular protein molecules (flagellin)
100
a curved structure where the base of the flagellum's filament is inserted
Hook
101
anchors the filament and hook to the CW by a rod and a series of 2 or 4 rings
Basal body
102
True or False
| The hook, rod, and rings of the flagellum allow the filament to rotate 360°
True
103
5 flagellar arrangements based on Messea's classification
1. monotrichous
2. lophotrichous
3. amphitrichous
4. peritrichous
5. atrichous
104
a single, polar flagellum
Monotrichous
105
examples of organisms w/ monotrichous flagellum
- Vibrio cholerae
- Campylobacter jejuni
- Pseudomonas aeruginosa
106
cells with a tuft of flagella on only one end
Lophotrichous
107
examples of organisms w/ lophotrichous flagella
Pseudomonas spp other than P. aeruginosa
108
both ends contain either a single flagellum or a tuft of flagella
Amphitrichous
109
examples of organisms w/ amphitrichous flagella
Pseudomonas spp other than P. aeruginosa
110
flagella is found all over the cell surface
Peritrichous
111
examples of organisms w/ peritrichous flagella
```
Salmonella typhi (agent of typhoid fever)
Proteus vulgaris
```
112
not flagellated organisms
Atrichous
113
examples of organisms w/ atrichous flagella
Shigella dysenteriae (agent of bacilliary
dysentery)
Klebsiella pneumoniae
114
Some spiral bacteria have _____ flagella that spiral tightly around the cell instead of protruding into the environment
Amphitrichous
115
When are flagella considered as endoflagella?
When they form an axial filament that wraps around the cell between the cell membrane and the outer membrane (periplasmic space)
116
examples of organisms w/ endoflagella
Spirochetes
117
functions of the flagella
- motility of the cell
- useful in ID of bacteria
- allow classification of prokaryotes into strains called serovars
118
What do you call it when flagellated bacteria change the antigenic type of its flagella?
Phase variation
119
sticky, proteinaceous, bristle-like projections used by gram (-) bacteria to adhere to one another and to substances in the environment
Fimbriae
120
example of an organism with fimbriae
Neisseria gonorrhoeae
121
tubules composed of a protein called pilin
Pilus/Pili
122
a type of pili that mediate the transfer of DNA from one cell to another
Sex/conjugal pili
123
importance of microfibrils (fimbriae & pili)
- 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
a membrane-associated cytoplasmic sac containing lamellar, tubular, or vseicular structures
Mesosome
125
2 types of mesosomes
- septal (DNA replication & cell division)
| - lateral (secretion)
126
highly coiled DNA intermixed with RNA, polyamines, and various proteins
Nucleoid
127
functions of nucleoid
- houses info for bacterial functions
| - directs synthesis of cellular products
128
small, roughly spherical cytoplasmic particles made up of 30% proteins and 70% RNA
Ribosomes
129
function of ribosomes
Protein synthesis
130
food reserves or storage granules also known as inclusion bodies
Cytoplasmic granules
131
2 types of cytoplasmic granules
- glycogen (glucose)
| - polyphosphate granules (inorganic phosphates)
132
other names of polyphosphate granules
- metachromatic granules
- volutin granules
- Babes-Ernst granules
133
examples of organisms with polyphosphate granules
- Mycobacterium tuberculosis (agent of TB)
- Corynebacterium diphtheriae (agent of
diphtheria)
- Yersinia pestis (agent of plague)
134
importance of cytoplasmic granules
- taxonomy as not all bacteria contain these granules
135
How are endospores formed?
By sporulation
136
When does sporulation occur?
- when there is a scarcity of food
| - when the spore-former encounters unfavorable environmental conditions
137
2 genera producing spores
- aerobic Genus Bacillus
| - anaerobic Genus Clostridium
138
the process of restoring the vegetative bacteria
Germination
139
What substance makes spores resistant to adverse environmental conditions?
Calcium dipicolinate
140
3 classification of spores based on location
- central
- subterminal
- terminal
141
How would you know if the spore is centrally located in the cell?
If there are equal amounts of stained cytoplasm on both sides of the spore
142
How would you know if the spore is subterminally located in the cell?
If there are unequal amounts of stained cytoplasm on both sides of the spore
143
How would you know if the spore is terminally located in the cell?
If all the stained cytoplasm is only on one side of the spore
144
importance of the presence of spores
- taxonomy: helps in identifying the organism
| - clinical: helps in sterilization
145
organism with a large terminal spore that is wider than the bacterial cell, giving it a drumstick appearance
Clostridium tetani
146
small, circular, double-stranded pieces of DNA
Plasmids
147
True or False
| The presence of plasmids in bacterial cells is essential to the viability of the organism
False, not essential
148
4 types of plasmids
1. F (fertility) factor
2. R (resistance) factor
3. Colicinogenic plasmid
4. Virulence plasmid
149
plasmid which provided for the discovery of bacterial sexuality
F factor
150
cells with F factor considered as males/donors
F+ cells
151
cells with F factor considered as females/recipients
F- cells
152
when cells have this factor, it can convert the entire cell population to become antibiotic resistant
R factor
153
plasmid that contains genes that code for synthesis of bactericidal proteins
Colicinogenic plasmid
154
Bactericidal proteins are called ____
Colicines
155
plasmid that contains genes that will code for toxin production
Virulence plasmid
