C3 - General Characteristic of Bacteria Flashcards
1
Q
[Prokaryotes or Eukaryotes] contain nucleic acids, proteins, lipids, and carbohydrates
A
Both
2
Q
[Prokaryotes or Eukaryotes] metabolize food, build proteins, and store energy
A
Both
3
Q
[Prokaryotes or Eukaryotes] DNA is found in the cell ‘s nucleus, which is separated from the cytoplasm by a nuclear membrane, and the DNA is found in multiple chromosomes
A
Eukaryotes
4
Q
[Prokaryotes or Eukaryotes] DNA is consistently associated with chromosomal proteins called histones and with nonhistone
A
Eukaryotes
5
Q
[Prokaryotes or Eukaryotes] Have a number of membrane-enclosed organelles
A
Eukaryotes
6
Q
[Prokaryotes or Eukaryotes] Cell walls, when present, are chemically simple
A
Eukaryotes
7
Q
[Prokaryotes or Eukaryotes] Cell division usually involves Mitosis
A
Eukaryotes
8
Q
[Prokaryotes or Eukaryotes] DNA is not enclosed within a membrane and is usually a singular circularly arranged chromosome
A
Prokaryotes
9
Q
[Prokaryotes or Eukaryotes] DNA is not associated with histones; other proteins are associated with the DNA.
A
Prokaryotes
10
Q
[Prokaryotes or Eukaryotes] Lack membrane-enclosed organelles
A
Prokaryotes
11
Q
[Prokaryotes or Eukaryotes] Usually divide by Binary Fission
A
Prokaryotes
12
Q
[Prokaryotes or Eukaryotes] Cell walls almost always contain the complex polysaccharide peptidoglycan
A
Prokaryotes
13
Q
→DNA is copied, and the cell splits into two cells
→involves fewer structures and processes than eukaryotic cell division
A
Binary Fission
14
Q
How is DNA organized in prokaryotes?
A
Circular chromosome
15
Q
Are prokaryotic DNA associated with histones?
A
No histones
16
Q
What is a key characteristic of prokaryotic cell walls?
A
Peptidoglycan
17
Q
Why is binary fission simpler than eukaryotic cell division?
A
Fewer processes
18
Q
Where is DNA located in eukaryotes?
A
Nucleus
19
Q
How is eukaryotic DNA organized?
A
Multiple chromosomes
20
Q
What proteins are associated with eukaryotic DNA?
A
Histones
21
Q
Do eukaryotes have membrane-enclosed organelles?
A
Yes
22
Q
What is the chemical nature of eukaryotic cell walls?
A
Chemically simple
23
Q
How do eukaryotes typically divide?
A
Mitosis
24
Q
What key molecules are found in both prokaryotic and eukaryotic cells?
A
Nucleic acids, proteins, lipids, carbohydrates
25
What processes are similar in both prokaryotic and eukaryotic cells?
Metabolism, protein synthesis, energy storage
26
What is a main structural difference between prokaryotic and eukaryotic cells?
Cell walls and membranes
27
What specialized structures are absent in prokaryotes but present in eukaryotes?
Organelles
28
→unicellular organisms that lack a nuclear membrane and true nucleus
BACTERIA
29
prokaryotes meaning
before kernel [nucleus]
30
classified as prokaryotes, having no mitochondria, endoplasmic reticulum (ER), or Golgi bodies
BACTERIA
31
Bacterial cell wall differences provide the basis for the
Gram stain
32
What characteristics vary in bacterial morphology?
Size, shape, arrangement
33
What is the typical size range for clinically relevant bacteria?
0.25 to 1 μm (width), 1 to 3 μm (length)
34
How does a bacterium compare in size to a virus?
Hundreds of times larger
35
How does a bacterium compare in size to a eukaryotic cell?
Ten times smaller
36
What can cause variation in size and shape within a bacterial population?
Asymmetric growth of the cell wall
37
What do you call bacteria that are circular in shape?
Cocci
38
What do you call bacteria that are ovoid in shape?
Coccobacilli
39
What do you call rod-shaped bacteria?
Bacillus
40
What do you call bacteria with tapered, pointed ends?
Fusiform
41
What do you call helical, corkscrew-shaped bacteria?
Spiral
42
What do you call bacteria that vary in length and number of helical turns?
Spirochetes
43
What do you call bacteria with no defined shape?
Pleomorphic
44
Bacterial Arrangements
a. Pairs
b. Chains
c. Grape-like clusters
d. Group of four
e. Packets of eight
f. Palisades
g. Chinese characters
45
Bacterial shapes
Cocci
Coccobacilli
Bacillus
Fusiform
Curved
Spiral
Pleomorphic
46
What do you call the outermost structure in bacteria?
Cell envelope
47
What membrane is found only in gram-negative bacteria?
Outer membrane
48
What is the bacterial cell wall composed of?
Peptidoglycan (murein layer)
49
What structure, found only in gram-negative bacteria, lies between the outer membrane and the cell membrane?
Periplasm
50
What membrane encloses the cytoplasm of bacterial cells?
Cytoplasmic (or cell) membrane
51
What type of bacteria has an outer membrane?
Gram-negative bacteria
52
What is the primary function of the outer membrane in gram-negative bacteria?
Initial barrier to the environment
53
What does the outer membrane serve as a primary barrier to?
Hydrophilic and hydrophobic compounds
54
What is the outer membrane composed of?
Lipopolysaccharide (bilayered structure)
55
What charge does the surface of gram-negative bacteria have due to the outer membrane?
Net negative charge
56
What role does the outer membrane play in bacterial disease?
Significant role in pathogenicity
57
facilitate the attachment of the outer membrane to the next internal layer in the cell envelope, the cell wall
Murein Lipoproteins
58
→protein structures scattered lipopolysaccharide macromolecules throughout the
→water-filled structures that control the passage of nutrients and other solutes, including antibiotics, through the outer membrane
→influence the extent to which various substances pass through the outer membranes of different bacteria
Porins
59
What is the cell wall also known as in bacteria?
Peptidoglycan (or murein layer)
60
What does the cell wall provide to the bacterial cell?
Shape and strength
61
What does the cell wall protect against?
Osmotic pressure changes and mechanical disruption
62
What is a primary target for the development of antimicrobial agents?
Cell wall synthesis and structure
63
What is the structure of the cell wall composed of?
Disaccharide-pentapeptide subunits
64
What are the alternating sugar components in peptidoglycan?
N-acetyl-D-glucosamine and N-acetyl-D-muramic acid (moieties)
65
How do polymers of peptidoglycan subunits cross-link?
peptide bridges
66
What is formed by the cross-linking of peptidoglycan sheets?
Multilayered, cross-linked structure
67
What is the peptidoglycan structure surrounding the entire bacterial cell called?
Murein sacculus (or sack)
68
How are different types of cell wall structures traditionally categorized?
According to staining characteristics
69
What are the major types of cell walls?
Gram-positive and gram-negative
70
What type of cell wall do mycobacteria have?
Acid-fast cell wall
71
stain gram-positive, have a modified cell wall called an ACID-FAST CELL WALL
Mycobacteria
72
microorganisms that have no cell wall
Mycoplasmas
73
What is the primary component of the gram-positive cell wall?
Thick peptidoglycan layer
74
What are the polysaccharide chains in the gram-positive cell wall made of?
N-acetyl-D-glucosamine (NAG) and N-acetyl-D-muramic acid (NAM)
75
How do many antibiotics affect gram-positive bacteria?
By preventing peptidoglycan synthesis
76
How does the peptidoglycan layer in gram-negative bacteria compare to gram-positive bacteria?
Thinner
77
Why are gram-negative bacteria less affected by certain antibiotics?
Different cell wall structure, thinner peptidoglycan
78
What component of the gram-positive cell wall is anchored to the peptidoglycan?
Teichoic acid
79
What are the polymers in teichoic acid composed of?
Glycerol or ribitol phosphate combined with sugars, amino acids, and amino sugars
80
What is lipoteichoic acid anchored to?
Plasma membrane (PM)
81
What components are unique to the gram-positive cell wall?
Teichoic acid and lipoteichoic acid
82
What other components may be present on the surface of the peptidoglycan layer of gram positive cell walls?
Antigenic polysaccharides
83
→ similar polymers, but the repeat units include sugar acids (eg, N-acetylmannosuronic or d-glucosuronic acid) instead of phosphoric acids
→ synthesized in place of teichoic acids when phosphate is limiting
Teichuronic acids
84
What are the two layers of the gram-negative cell wall?
Inner peptidoglycan layer, Outer membrane
85
What is found outside the peptidoglycan layer in gram-negative bacteria?
Outer membrane
86
What components make up the outer membrane of gram-negative bacteria?
Proteins, phospholipids, lipopolysaccharide (LPS)
87
What are the three regions of lipopolysaccharide (LPS)?
O-specific polysaccharide, Core polysaccharide, Lipid A
88
What is the antigenic region of LPS called?
O-specific polysaccharide
89
What are the components of the core polysaccharide in LPS?
Ketodeoxyoctanoic acid (KDO) and heptose
90
What is the inner, major constituent of LPS also known as endotoxin?
Lipid A
91
How does LPS contribute to the bacterial surface?
Negative charge stabilization
92
What is LPS considered to be due to its effects?
Endotoxin
93
LPS main function
Vital in evading the host defenses
94
→consists of phosphorylated glucosamine disaccharide units to which are attached a number of long-chain fatty acids
→responsible for producing fever and shock conditions in patients infected with gram-negative bacteria
Lipid A moiety
95
What does the lipid A moiety consist of?
Phosphorylated glucosamine disaccharide units with long-chain fatty acids
96
What conditions can the lipid A moiety produce in patients infected with gram-negative bacteria?
Fever and shock
97
What is one function of the outer membrane as a barrier?
blocks hydrophobic compounds and harmful substances
98
How does the outer membrane act as a sieve?
Allows water-soluble molecules through porins
99
What does the outer membrane provide that enhances attachment to host cells?
Attachment sites
100
What role does the strong negative charge of the outer membrane play?
Evading phagocytosis
101
What does the outer membrane act as a barrier to?
Toxic substances
102
Outer membrane function:
barrier
sieve
evading phagocytosis
103
What bounds the periplasmic space in gram-negative bacteria?
Internal surface of the outer membrane and external surface of the cellular membrane
104
What does the periplasmic space contain besides the thin peptidoglycan layer?
Murein layer, gel-like matrix with nutrient-binding proteins
105
What is the function of nutrient-binding proteins in the periplasmic space?
Assist in the capture of nutrients
106
Found in the periplasmic space that assists in the capture of nutrients
nutrient-binding proteins
107
What type of enzymes are found in the periplasmic space?
Enzymes involved in degradation of macromolecules and detoxification
108
What does the periplasmic space help detoxify?
Environmental solutes and antibiotics
109
What type of cell wall structure do acid-fast bacteria have?
Gram-positive
110
What does the acid-fast cell wall contain that is bound to the exterior of the cell wall?
Waxy layer of glycolipids and fatty acids (mycolic acid)
111
What percentage of the acid-fast cell wall is lipid?
More than 60%
112
What is the major lipid component in the acid-fast cell wall?
Mycolic acid
113
How does mycolic acid affect the permeability of the cell wall?
Forms a hydrophobic lipid shell, affecting permeability
114
Why is Mycobacterium spp. difficult to stain with the Gram stain?
Due to its lipid-rich cell wall
115
What color do Mycobacterium and Nocardia stain with the Gram stain?
Faint blue (gram-positive)
116
What type of stain is best for Mycobacterium and Nocardia?
Acid-fast stain
117
What do organisms that lack a cell wall contain in their cell membranes?
Sterols
118
How does the absence of a cell wall affect the rigidity of these organisms?
They lack rigidity
119
What are some examples of organisms without a cell wall?
Mycoplasma, Ureaplasma
120
Gram-positive and gram-negative cells can lose their cell walls and grow as_________ in media supplemented with serum or sugar to prevent osmotic rupture of the cell membrane
L-forms
121
What is used in media to prevent osmotic rupture of L-forms?
Serum or sugar
122
What is the deepest layer of the cell envelope in both gram-positive and gram-negative bacteria?
Cytoplasmic (inner) membrane
123
What is the composition of the cytoplasmic membrane?
Phospholipid bilayer, proteins (70%)
124
What is a primary function of the cytoplasmic membrane?
Osmotic barrier
125
Which organism incorporates sterols like cholesterol into their cytoplasmic membranes?
Mycoplasma
126
What functions are performed by the cytoplasmic membrane?
Transport, enzyme housing, ATP generation, cell motility, chromosomal segregation, molecular sensing, electron transport, excretion
127
What type of transport relies on diffusion and uses no energy?
Passive transport
128
What is an example of passive transport?
Simple diffusion, facilitated diffusion
129
What is facilitated diffusion?
Selective, no energy, solute concentration outside is never exceeded inside
130
form selective channels that facilitate the passage of specific molecules
Channel proteins
131
accounts for the entry of very few nutrients, including dissolved oxygen, carbon dioxide, and water itself
Simple diffusion
132
What does active transport move across the cell membrane?
Molecules against a concentration gradient using energy
133
What type of transport uses ion gradients for moving molecules?
Ion-coupled transport
134
What are the three basic types of ion-coupled transport?
Uniport, Symport, Antiport
135
What is the function of uniport transport?
Transport of a substrate independent of any coupled ion
136
What does symport transport involve?
Simultaneous transport of two substrates in the same direction
137
What does antiport transport involve?
Simultaneous transport of two like-charged compounds in opposite directions
138
Which vital cellular processes occur on the cytoplasmic membrane related to the cell wall?
Housing enzymes for outer membrane synthesis, cell wall synthesis, and assembly/secretion of extracytoplasmic substances
139
How does the cytoplasmic membrane generate energy for the cell?
Through ATP generation
140
What is the role of the cytoplasmic membrane during bacterial replication?
Mediates chromosomal segregation
141
How does the cytoplasmic membrane help bacteria respond to environmental changes?
It houses molecular sensors that monitor chemical and physical changes
142
What is the function of the cytoplasmic membrane in aerobic species?
Electron transport and oxidative phosphorylation
143
What does the cytoplasmic membrane excrete to aid in the breakdown of macromolecules?
Hydrolytic exoenzymes
144
What type of transport uses ATP directly to move solutes into the cell?
ABC transport
145
In gram-negative bacteria, what facilitates the transport of many nutrients?
Specific binding proteins in the periplasmic space
146
In gram-positive bacteria, where are binding proteins located?
Attached to the outer surface of the cell membrane
147
What type of metabolism allows bacteria to use energy efficiently by coupling transport with metabolism?
Group translocation
148
Why is group translocation not considered active transport?
It does not involve a concentration gradient
149
What compounds chelate iron and promote its transport as a soluble complex?
Siderophores
150
How do some pathogenic bacteria acquire iron from the host?
By binding to host proteins like transferrin and lactoferrin
151
Cytoplasmic structures
Ribosomes
Genome
Plasmid
Inclusion Bodies
Endospores/ Asexual spores
152
What is the site of protein biosynthesis in bacteria and gives the cytoplasm a granular structure?
Ribosomes
153
What size are bacterial ribosomes?
70S (50S, 30S)
154
What antibiotics attach to the 30S ribosomal subunit and interfere with protein synthesis?
Streptomycin and Gentamicin
155
What antibiotics attach to the 50S ribosomal subunit and interfere with protein synthesis?
Erythromycin and Chloramphenicol
156
What is the bacterial genome made of?
A single, circular chromosome
157
What structure is the bacterial chromosome attached to?
Mesosome
158
What does the bacterial nucleoid test positive for?
Feulgen stain
159
Which bacteria have dissimilar chromosomes compared to the typical single circular genome?
Vibrio cholera and Brucella melitensis
160
Extrachromosomal, double-stranded DNA elements associated with virulence
plasmids
161
What role do plasmids play in bacterial cells?
Code for antibiotic resistance and toxin production
162
Large plasmid provides resistance to what antibiotics
β-lactam antibiotics like penicillin
163
Small plasmid is responsible for resistance to
tetracyclines and chloramphenicol
164
→Not essential for bacterial growth so a bacterial cell may or may not contain a plasmid
→Sometimes disappears during cell division and it can make bacteria (mostly Gram-neg) pathogenic
Plasmid
165
Consists of a single continuous circular molecule ranging in size from 0.58 to almost 10 million base pair Exeptions:
Borrelia burgdorferi and Streptomyces coelicolor
166
→Serve as the energy source or food reserve of the bacteria or as a reservoir of structural bulding blocks
Inclusions Bodies
167
What is the role of inclusion bodies in bacteria?
Serve as energy source or food reserve
168
What are inclusion bodies primarily composed of to lessen osmotic pressure?
Polysaccharides
169
What is the storage form of glucose in bacteria?
Glycogen
170
What is the storage form for inorganic phosphates in bacteria?
Polyphosphate granules
171
What are the phosphate granules in Corynebacterium diphtheriae called?
Babes-Ernst bodies
172
What inclusion bodies are found in Yersinia pestis?
Bipolar bodies
173
What are the granules found in Mycobacterium tuberculosis called?
Much granules
174
→Lipid like compound consisting of chains of B-hyroxybutyric acid units connected through ester linkages →Produced when the source of nitrogen, sulfur or phosphorus is limited and there is excess carbon in the medium
Poly-B-hydroxybutyric acid (PHB)
175
Under what condition is poly-B-hydroxybutyrate produced by bacteria?
When nitrogen, sulfur, or phosphorus is limited, but carbon is in excess
176
What are PHB and glycogen used as when protein and nucleic acid synthesis resume?
Carbon source
177
What kind of granules store hydrogen sulfide and thiosulfate?
Sulfur granules
178
Which bacterium has Babes-Ernst bodies?
Corynebacterium diphtheriae
179
Which bacterium has bipolar bodies?
Yersinia pestis
180
Which bacterium has Much granules?
Mycobacterium tuberculosis
181
What are small, dormant structures inside bacterial cells that aid survival?
Endospores
182
What substance is an endospore composed of?
Calcium dipicolinate
183
Calcium dipicolinate is made of
dipicolinic acid and calcium ions
184
Which bacterial genus produces terminal spores?
Clostridium tetani
185
Which bacterial genus produces subterminal spores?
Clostridium botulinum
186
Which bacterial genus produces central spores?
Bacillus anthracis
187
Endospores are produced in what type of bacterial cells?
Vegetative cells of some Gram-positive bacteria
188
Endospores are responsible for?
perpetuation, but not muliplication
189
Endospores Core are called
Spore protoplast
190
What does the core of an endospore contain?
A complete nucleus and protein-synthesizing apparatus
191
What is the innermost layer of an endospore that becomes the cell wall of the germinating vegetative cell?
Spore wall
192
What is the thickest layer of the spore envelope that contains an unusual type of peptidoglycan?
Cortex
193
What is the layer of the endospore composed of keratin-like protein that provides resistance to antibacterial agents?
Coat
194
What is the outermost layer of the endospore composed of proteins, lipids, and carbohydrates?
Exosporium
195
Exosporium consists of
paracrystalline basal layer
hairlike outer region
196
Which bacteria have an exosporium?
Bacillus anthracis and Bacillus cereus
197
Cellular Appendages
Glycocalyx
Flagella
Pili (Fimbria)
198
What is the outward complex of polysaccharide on the bacterial surface called?
Glycocalyx
199
What role does the glycocalyx play for bacteria?
Helps the bacteria attach to the surface of solid objects or tissues.
200
How does a capsule differ from a slime layer?
A capsule is organized and firmly attached to the cell wall, while a slime layer is unorganized and loosely attached.
201
Where is the capsule located in gram-positive and gram-negative bacteria?
Immediately exterior to the murein layer in gram-positive bacteria and
the outer membrane in gram-negative bacteria.
202
What exception exists to the typical polysaccharide capsule composition in bacteria?
Bacillus anthracis and Bacillus licheniformis have capsules made of Poly-D-glutamic acid.
203
How does the capsule protect bacteria?
It acts as a virulence factor by resisting phagocytosis and desiccation.
204
Why might a capsule need to be removed in laboratory identification?
To detect the somatic (cell wall) antigens present.
205
How is capsule removal typically accomplished?
By boiling a suspension of the microorganism.
206
Why doesn’t a bacterial capsule stain with common laboratory stains like Gram or India ink?
It doesn’t ordinarily stain and appears as a clear “halo”-like area.
207
It can inhibit phagocytosis or aid in the adherence of bacteria to host tissues or synthetic implants.
slime layer
208
→Unorganized material that is loosely attached to the cell
wall
→Made up of polysaccharide
→Can either inhibit phagocytosis or aid in the adherence
of the bacteria to the host tissue or synthetic implants
→facilitates and maintains bacterial colonization of
biologic (e.g., teeth) and inanimate (e.g., prosthetic
heart valves) surfaces through the formation of biofilms
Slime Layer
209
How does the slime layer contribute to biofilm formation?
It facilitates and maintains bacterial colonization on biological (e.g., teeth) and inanimate (e.g., prosthetic heart valves) surfaces.
210
It helps cells attach to their environment and each other, protects the cells, facilitates communication, and enables survival.
Extracellular Polymeric Substance (EPS) in biofilms
211
→exterior protein filaments that rotate and cause
bacteria to be motile
→complex structures, mostly composed of the protein
flagellin, intricately embedded in the cell envelope
Flagella
212
What protein primarily makes up flagella?
Flagellin
213
What is the role of flagella in bacteria?
Motility and aiding in disease-causing ability
214
What is the diameter of bacterial flagella?
12–30 nm
215
What antigen type is found in flagella?
H antigens
216
Which bacteria exhibit gliding motility?
Capnocytophaga, Cyanobacteria, Myxobacteria
217
What is the function of the hook in flagella?
It connects the basal body to the flagellum.
218
How does the basal body differ between gram-positive and gram-negative bacteria?
Gram-positive has one pair of rings, gram-negative has two pairs.
219
What is the filament of the flagellum made of?
Flagellin arranged in a helical structure.
220
What is bacterial motility?
Movement through "runs" and "tumbles."
221
What causes a "tumble" in bacterial movement?
Reversal of flagellar rotation
222
What unique movement ability does Proteus have?
Swarming across solid media.
223
endowed with many flagella
→ can "swarm," or show rapid wavelike movement
across a solid culture medium
Proteus
224
bacterium moves in one direction
for a length of time
“Run" or “Swim”
225
What is the term for bacteria without flagella?
Atrichous
226
What is the term for bacteria with a single flagellum at one end?
Monotrichous
227
What is the term for bacteria with a single flagellum at both ends?
Amphitrichous
228
What is the term for bacteria with a tuft or group of flagella at one or both ends?
Lophotrichous
229
What is the term for bacteria with flagella covering the entire surface?
Peritrichous
230
What are the bundles of fibrils that spiral around a spirochete cell called?
Axial filaments
231
What is the location where axial filaments are anchored in spirochetes?
One end of the spirochete
232
What type of movement is produced by the rotation of axial filaments in spirochetes?
Spiral motion
233
What bacterial movement is similar to how a corkscrew moves through a cork?
Axial filament movement
234
What group of bacteria move using axial filaments or endoflagella?
Spirochetes
235
Which method is best for observing true motility and Brownian movement?
Hanging drop method
236
What term describes bacteria moving in a definite direction?
True motility
237
What type of movement occurs when bacteria bounce back and forth due to water molecules?
Brownian movement
238
What is the term for bacterial movement toward or away from a stimulus?
Taxis
239
What method is best for observing motility and includes using a hanging drop?
Hanging drop method
240
Ways of demonstrating motility in the Lab:
✓Hanging Drop Method
✓SIM
✓Flagellar staining
✓Serologic test
✓Fluorescent Antibody Technique(FAT)
✓Swarming Phenomenon
✓Darkfield Microscopy
241
What laboratory test is used for motility and involves sulfur, indole, and motility testing?
SIM
242
Which technique uses stains to visualize bacterial flagella?
Flagellar staining
243
Which test involves antibodies to detect bacterial motility?
Serologic test
244
What method uses antibodies tagged with fluorescent dyes to detect bacteria?
Fluorescent Antibody Technique (FAT)
245
What phenomenon involves the movement of bacteria across solid media?
Swarming phenomenon
246
Which microscopy method helps visualize bacterial motility in the lab?
Darkfield microscopy
247
What are hairlike structures that help bacteria attach to host cells called?
Pili (Fimbriae)
248
What protein makes up the structural subunits of pili?
Pilin
249
What is the type of motility involving jerky, intermittent movements due to pilus retraction?
Twitching motility
250
What kind of pili are involved in bacterial adherence to surfaces and contribute to virulence?
Common pili (Ordinary pili)
251
What is the term for the specialized pilus that transfers DNA during bacterial conjugation?
Sex pilus
252
Which bacterial cells produce the protein F factor for conjugation?
F-positive cells
253
In which bacteria are fimbriae the site of the M protein, the main surface antigen?
Streptococci
254
What acid associated with fimbriae helps group A streptococci adhere to epithelial cells?
Lipoteichoic acid
255
What bacteria can produce pili of different antigenic types?
Neisseria gonorrhoeae
256
→hairlike, proteinaceous structures that extend
from the cell membrane into the external
environment; some may be up to 2 μm long
→Hair-like microfibrils usually produced by
flagellated Gram-negative bacteria observable
by electron microscopy
→serve as adhesins that help bacteria attach to
animal host cell surfaces, often as the first step in
establishing infection
Pili (Fimbria)
257
Examples of bacteria with twitching motility due to powerstroke
Pseumdomons aeruginosa, Neisseria gonorrheae,
and some strains of E. coli
258
→present only in cells that produce a protein referred to
as the F factor
Sex pilus
