Bacterial Structure, Function, and Growth Flashcards
1
Q
Lipopolysaccharide (LPS) contains lipid A, ____, and O side chain oligosaccharides.
A
core polysaccharide
1
Q
What are pili?
A
long, slender, hair-like structures on the bacterial surface that help adhesion
1
Q
What is a virus that infects bacteria?
A
bacteriophage
2
Q
Name the 7 characteristic bacterial cell shapes.
A
1) coccus 2) bacillus 3) coccobacillus 4) fusiform bacillus 5) vibrio 6) spirillum 7) spirochete
2
Q
How does isoniazid work?
A
it inhibits lipid synthesis in Mycobacteria
3
Q
What is the electron transport system and where is it located in a bacterium?
A
the principal source for generating the proton motive force during respiration; the cytoplasmic membrane
4
Q
_____ appears to function like intermediate filaments in eukaryotes.
A
CreS
4
Q
During exponential growth, the rate of cell division is _____.
A
maximal
4
Q
In nature, bacteria spend most of their time in the ____ phase.
A
stationary
5
Q
How do chloramphenicols work?
A
bind to the 50S ribosomal subunit and inhibits peptidyl transferase and peptide bond formation
6
Q
What is the exponential/logarithmic phase?
A
when the rate of increase of cell number is proportional to the number of cells already present
7
Q
What is respiration?
A
ATP generated by an e- transport chain using O2 as the terminal e- acceptor
8
Q
What do the O side chain oligosaccharides do?
A
function as somatic antigens (O antigen)
8
Q
What are flagella?
A
organs of motility that originate in the cytoplasmic membrane
8
Q
How do tetracyclines work?
A
bind to the 30S ribosome and inhibit binding of aminoacyl tRNA
9
Q
FtsZ resembles _____ in eukaryotes.
A
tubulin
9
Q
The _____ of gram-negative bacteria is located on the outer leaflet; the inner leaflet contains _____.
A
lipopolysaccharide (LPS); phospholipids
10
Q
In gram-positive bacteria, the tetrapeptides are cross-linked from ____ to D-ala with an intervening peptide such as pentaglycine.
A
L-lys
11
Q
What is the internal osmotic pressure for a gram-positive bacterium?
A
about 20 atm
12
Q
What is another name for pili?
A
fimbriae
12
Q
What is the death phase?
A
a decrease in the number of viable bacteria
12
Q
Which drugs inhibit nucleic acid synthesis?
A
1) quinolones 2) rifampicin
13
Q
____ and ____ resemble actin in eukaryotes.
A
MreB; ParM
14
Q
In gram-negative bacteria, the tetrapeptides are cross-linked from DAP to ____.
A
D-ala
15
Which drug inhibits RNA polymerase and interferes with transcription initiation?
rifampicin
16
Most capsular polysaccharides are \_\_\_\_\_, and some are used as vaccine components.
antigenic
16
How does vancomycin work?
inhibits the utilization of lipid-linked intermediate in peptidoglycan synthesis
17
What does polycistronic mean?
encode for more than one protein product
18
Bacterial mRNAs may be \_\_\_\_\_.
polycistronic
19
What is the lag phase?
when the bacteria are "adjusting" by inducing new enzymes and establishing a proper intracellular environment
20
\_\_\_\_\_ consists of a polymer of repeating units of 2 hexose sugars, N-acetylglucosamine (GlcNAc) and N-acetylmuramic (MurNAc) acid.
Peptidoglycan
21
Heterotrophic bacteria obtain both ____ and _____ by subjecting nutrients to fermentation and respiration.
energy; reducing power
22
Lipoteichoic acids are attached to _____ and help \_\_\_\_\_.
the underlying cytoplasmic membrane; anchor the cell wall to the membrane
22
What is another name for the bacterial cytoplasmic membrane?
inner membrane (in gram-negative bacteria)
22
What is the purpose of the cytoplasmic membrane?
it's the barrier btw the inside and outside of the bacterial cell
22
Which drug interferes with folate metabolism by inhibiting dihydrofolate reductase?
trimethoprim
23
Lipopolysaccharide (LPS) contains lipid A, core polysaccharide, and \_\_\_\_\_.
O side chain oligosaccharides
23
If the environment remains favorable, bacteria are capable of _____ growth and division.
unlimited
23
What is selective toxicity?
using a drug concentration that affects the bacteria and is tolerated by the host
23
What drugs binds to the 50S ribosomal subunit and inhibits peptidyl transferase and peptide bond formation?
chloramphenicols
23
\_\_\_\_\_ are structural analogs of p-aminobenzoic acid (PABA), which is a component of folic acid.
Sulfonamides
24
Which drug inhibits alanine racemace, preventing the formation of muramyl pentapeptide in the peptidoglycans?
cycloserine
25
\_\_\_\_ have a thick, extensively cross-linked peptidoglycan layer that also contains teichoic acids.
Gram-positive bacteria
26
Which drug inhibits the utilization of lipid-linked intermediate in peptidoglycan synthesis?
vancomycin
27
What is sporulation?
generation of spores because of a lack of C, N, or P
28
What is phage conversion?
a change in the phenotype of a host bacterium as a consequence of gene expression encoded by a bacteriophage
29
Sulfonamides are structural analogs of \_\_\_\_\_, which is a component of folic acid.
p-aminobenzoic acid (PABA)
30
How do the macrolides and lincomycins work?
bind to the 23S ribosomal RNA and the 50S subunit and inhibit peptidyl transferase
32
The lipopolysaccharide (LPS) of gram-negative bacteria is located \_\_\_\_\_; the ______ contains phospholipids.
on the outer leaflet; inner leaflet
32
Describe the bacterial chromosome.
usually a single, double-stranded, circular DNA molecule (but can be linear or multiple)
33
In gram-positive bacteria, the tetrapeptides are cross-linked from L-lys to ____ with an intervening peptide such as pentaglycine.
D-ala
35
What is peptidoglycan made of?
a polymer of repeating units of 2 hexose sugars, N-acetylglucosamine (GlcNAc) and N-acetylmuramic (MurNAc) acid
36
What is fermentation?
organic compounds serve as both e- donors and acceptors; no net oxidation of substrates; usu anaerobic conditions
37
Teichoic acid, found in gram-positive bacteria, has a repeating _____ backbone covalently attached to the peptidoglycan layer.
polyglycerol-P or polyribitol-P
37
Counterclockwise flagellar motion results in \_\_\_\_; clockwise results in \_\_\_\_\_.
swimming; tumbling
37
What drug binds to the 30S ribosome and inhibits binding of aminoacyl tRNA?
tetracyclines
39
\_\_\_\_\_ have a thin, sparsely cross-linked peptidoglycan layer and other major components located exterior to it.
Gram negative bacteria
40
How does cycloserine work?
inhibits alanine racemace, preventing the formation of muramyl pentapeptide in the peptidoglycans
42
Gram-positive bacteria have a thick, extensively cross-linked peptidoglycan layer that also contains \_\_\_\_.
teichoic acids
43
What are the 2 forms of energy currency in the bacterial cell? What enzyme interconverts them?
1) ATP 2) electrochemical gradients (proton motive force) --- membrane ATPase
44
Which drug is a cationic surfactant that disrupts the outer and cytoplasmic membrane?
polymyxins
45
How is trimethoprim selective?
bacteria are 50,000 times more sensitive to it than the host
46
What are the functions of the cytoplasmic membrane? (5)
1) electron transport system 2) transport of metabolites 3) biosynthesis of lipids 4) DNA replication 5) flagellar rotation
47
Plasmids in pathogenic bacteria often encode \_\_\_\_\_; _____ carry genes that determine resistance to antibiotics.
virulence factors; R-factors
48
What are capsules?
loose, gelatinous outer surface layers consisting of complex polysaccharides that enhance virulence
49
\_\_\_\_\_ play a role in bacterial conjugation.
Sex pilli
51
Where does lysozyme cleave the peptidoglycan?
the glycosidic bond between MurNAc and GlcNAc
52
What is the nucleoid?
a distinct region of the cytoplasm where the DNA of bacteria is located
53
The ____ phase is when the bacteria are "adjusting" by inducing new enzymes and establishing a proper intracellular environment .
lag
55
The _____ is typically much greater in gram-positive bacteria.
extent of cross-linking
55
What drugs target the outer and cytoplasmic membrane?
polymyxin
56
What are obligate intracellular bacteria?
bacteria that can only grow within a eukaryote
58
Teichoic acid, found in \_\_\_\_\_, has a repeating polyglycerol-P or polyribitol-P backbone covalently attached to the peptidoglycan layer.
gram-positive bacteria
59
Lipopolysaccharide (LPS) contains \_\_\_\_\_, core polysaccharide, and O side chain oligosaccharides.
lipid A
60
What are polyribosomes?
several ribosomes interacting with a single mRNA
62
What enzyme hydrolyzes peptidoglycan?
lysozyme
63
These residues are linked to tetrapeptide chains that contain aas only found in bacterial cell walls.
N-acetylmuramic (MurNAc)
64
\_\_\_\_\_ forms a rigid mesh that surrounds the cytoplasmic membrane.
Peptidoglycan
64
In gram-negative bacteria, the tetrapeptides are cross-linked from ____ to D-ala.
DAP
65
What drug inhibits lipid synthesis in Mycobacteria?
isoniazid
66
How does metronidazole work?
interferes with anaerobic metabolism
68
What does peptidoglycan do?
it surrounds the cytoplasmic membrane and forms a rigid mesh
69
MreB and ParM resemble ____ in eukaryotes.
actin
70
How do capsules enhance virulence?
they enable the bacteria to resist phagocytosis
70
What drug interferes with anaerobic metabolism?
metronidazole
71
What are the 4 distinct phases of the bacterial growth curve?
1) lag phase 2) exponential/logarithmic phase 3) stationary phase 4)
73
What organelles/cellular components do bacteria have, as opposed to eukaryotes?
1. cell wall (peptidoglycan) 2. 70S ribosome
74
What are the bacterial 70S ribosomes related to?
eukaryotic mitochondria
75
The DNA genomes of _____ can integrate into bacterial chromosomes and often carry genes that encode bacterial toxins, virulence factors, or resistance to antibiotics.
temperate bacteriophages
76
What is a plasmid?
an extra-chromosomal, self-replicating DNA molecule usu not essential for bacterial viability
78
Name 3 bacterial cytoskeletal structural elements.
1) FtsZ 2) MreB 3) CreS
79
Which drugs bind to the 23S ribosomal RNA and the 50S subunit and inhibit peptidyl transferase?
macrolides and lincomycins
80
What is the stationary phase?
when cell growth decreases dramatically or stops bc of nutrient consumption and accumulation of toxic metabolites; growth is balanced by death; increased resistance to antibiotics is seen
81
How do quinolones work?
inhibit DNA gyrase and topoisomerase
83
\_\_\_\_\_ distribution means the flagella are on one end of the cell.
Polar
85
The distinct region of the cytoplasm where the DNA of bacteria is located is called the \_\_\_\_.
nucleoid
87
What ribosomes do bacteria have?
70S
88
Most flagella are antigenic, and the _____ used to classify enteric bacteria are flagellar antigens.
H antigens
88
What are the minimum requirements for growth for most bacteria?
nutrient medium containing inorganic ions, a carbon source, and an energy source
90
Why does a bacterium have a rigid cell wall?
1. to resist osmotic lysis 2. to maintain cell shape
90
What is the generation time?
doubling time
91
The outer membrane of gram-negative bacteria contains \_\_\_\_\_, \_\_\_\_\_, and \_\_\_\_\_.
lipopolysaccharides; lipoproteins; porins
93
Name 3 amino acids found only in bacterial cell walls.
1. meso-diaminopimelic acid (DIP) 2. D-glutamic acid 3. D-alanine
94
\_\_\_\_\_ flagellar motion results in swimming; _____ results in tumbling.
Counterclockwise; clockwise
96
What do antibodies to pili do?
block bacterial adherence and confer resistance to infection
97
\_\_\_\_\_ are important for bacterial chemotaxis.
Flagella
97
What is an extra-chromosomal, self-replicating DNA molecule usu not essential for bacterial viability called?
a plasmid
98
What is the internal osmotic pressure in a gram-negative bacterium?
about 5 atm
100
What are autotrophic bacteria?
bacteria that obtain their C exclusively from CO2
101
Which drugs bind to target proteins on the 30S ribosome to inhibit protein synthesis?
aminoglycosides
102
Name 4 drugs that inhibit metabolism in bacteria.
1) sulfonamides 2) trimethoprim 3) isoniazid 4) metronidazole
104
How is the cytoplasmic membrane different than the plasma membrane of animal cells?
1. usually contains no sterols 2. has a much higher protein content (60-70%)
105
What is N-acetylmuramic (MurNAc)?
a hexose sugar that makes up peptidoglycan; is linked to tetrapeptide chains that contain aas that are only found in bacterial cell walls
106
\_\_\_\_\_\_ is determined by both intracellular cytoskeletal elements and by rigid components of the cell wall.
Bacterial cell shape
106
Which drug inhibits the final transpeptidation rxn in cross-linking peptidoglycan?
beta-lactam
107
How do beta-lactams work?
inhibit the final transpeptidation rxn in cross-linking peptidoglycan
108
How does trimethoprim work?
interferes with folate metabolism by inhibiting dihydrofolate reductase
110
What is the inoculum?
the starting cells
112
What are the components of the bacterial cytoplasm? (3)
1) ribosomes 2) nucleoid 3) chromosome (plasmids)
113
Where is the genetic material found in a bacterium?
in the cytoplasm
114
Organisms that grow in the presence of O2 produce \_\_\_\_\_, such as ____ or \_\_\_\_\_.
toxic oxygen metabolites; hydrogen peroxide; superoxide
115
What is N-acetylglucosamine (GlcNAc)?
a hexose sugar that makes up peptidoglycan
116
What are porins?
transmembrane channels that allow hydrophilic molecules of
117
How does rifampicin work?
inhibits RNA polymerase and interferes with transcription initiation
118
Sulfonamides are structural analogs of p-aminobenzoic acid (PABA), which is a component of \_\_\_\_\_.
folic acid
120
What organelles/cellular components do bacteria lack, as opposed to eukaryotes?
1. a nuclear membrane 2. ER 3. mitotic spindle 4. mitochondria 5. chloroplasts
121
The ____ phase is when cell growth decreases dramatically or stops bc of nutrient consumption and accumulation of toxic metabolites; growth is balanced by death; increased resistance to antibiotics is seen.
stationary
122
In gram-positive bacteria, the tetrapeptides are cross-linked from L-lys to D-ala with an intervening peptide such as \_\_\_\_\_\_.
pentaglycine
124
Bacterial cell shape is determined by both\_\_\_\_\_ and by \_\_\_\_\_.
intracellular cytoskeletal elements; rigid components of the cell wall
126
What does the cytoplasmic membrane consist of?
a lipid bilayer of phospholipids and proteins
127
How do aminoglycosides work?
bind to target proteins on the 30S ribosome to inhibit protein synthesis
128
Gram negative bacteria have a _____ and other major components located exterior to it.
thin, sparsely cross-linked peptidoglycan layer
129
How do bacterial cells divide?
binary fission
130
The extent of cross-linking is typically much greater in \_\_\_\_\_.
gram-positive bacteria
132
Which drugs target the peptidoglycan?
1) beta-lactams 2) vancomycin 3) cycloserine
133
What is Lipid A?
the toxic component of endotoxin
135
What are fastidious bacteria?
bacteria that need growth factors like aas, vitamins, purines, pyrimidines, and inorganic ions
136
Heterotrophic bacteria obtain both energy and reducing power by subjecting nutrients to _____ and \_\_\_\_\_.
fermentation; respiration
137
What is anaerobic respiration?
bacteria using inorganic substrates such as nitrate or nitrite as the terminal e- acceptor
138
There is no ____ surrounding the bacterial DNA.
nuclear membrane
139
What is a change in the phenotype of a host bacterium as a consequence of gene expression encoded by a bacteriophage called?
phage conversion
140
Name 5 major antibacterial targets.
1) cell walls (peptidoglycan) 2) outer and cytoplasmic membrane 3) protein synthesis at the ribosome 4) nucleic acid synthesis 5) metabolic inhibition
142
CreS appears to function like _____ in eukaryotes.
intermediate filaments
143
How do sulfonamides work?
inhibit the formation of folic acid, preventing nucleic acid synthesis
145
How does polymyxin work?
it's a cationic surfactant that disrupts the outer and cytoplasmic membranes
146
\_\_\_\_, found in gram-positive bacteria, has a repeating polyglycerol-P or polyribitol-P backbone covalently attached to the peptidoglycan layer.
Teichoic acid
147
During sporulation, bacteria differentiate to form _____ that have no \_\_\_\_\_.
highly resistant, dehydrated forms (spores); metabolic activity
148
Bacteria that grow in the presence of O2 produce ______ or ______ that protect them against toxic ROS.
catalase/peroxidase, superoxide dismutase (SOD)
149
Which drug inhibits DNA gyrase and topoisomerase?
quinolones
150
Flagella can be ____ or ____ in their distribution.
peritrichous; polar
151
\_\_\_\_\_ are attached to the underlying cytoplasmic membrane and help anchor the cell wall to the membrane.
Lipoteichoic acids
152
How are sulfonamides selective?
bacteria cannot utilize pre-formed folic acid (humans can) and synthesize folic acid on their own (humans do not)
153
Because there is no nuclear membrane, _____ can occur in bacteria.
transcription and translation can occur as a coupled process
154
\_\_\_\_\_\_ distribution means the flagella are all over the surface.
Peritrichous
155
What are heterotrophic bacteria?
bacteria requiring an organic carbon source
156
What drugs are inhibitors of protein synthesis at the ribosome?
1) aminoglycosides 2) tetracyclines 3) chloramphenicol 4) macrolides
157
\_\_\_\_ resembles tubulin in eukaryotes.
FtsZ
