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Lindsey's D&D Unit 3 > Bacterial Structure, Function, and Growth > Flashcards

Bacterial Structure, Function, and Growth Flashcards

1
Q

Lipopolysaccharide (LPS) contains lipid A, ____, and O side chain oligosaccharides.

A

core polysaccharide

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1
Q

What are pili?

A

long, slender, hair-like structures on the bacterial surface that help adhesion

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1
Q

What is a virus that infects bacteria?

A

bacteriophage

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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

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2
Q

How does isoniazid work?

A

it inhibits lipid synthesis in Mycobacteria

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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

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4
Q

_____ appears to function like intermediate filaments in eukaryotes.

A

CreS

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4
Q

During exponential growth, the rate of cell division is _____.

A

maximal

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4
Q

In nature, bacteria spend most of their time in the ____ phase.

A

stationary

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5
Q

How do chloramphenicols work?

A

bind to the 50S ribosomal subunit and inhibits peptidyl transferase and peptide bond formation

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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

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7
Q

What is respiration?

A

ATP generated by an e- transport chain using O2 as the terminal e- acceptor

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8
Q

What do the O side chain oligosaccharides do?

A

function as somatic antigens (O antigen)

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8
Q

What are flagella?

A

organs of motility that originate in the cytoplasmic membrane

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8
Q

How do tetracyclines work?

A

bind to the 30S ribosome and inhibit binding of aminoacyl tRNA

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9
Q

FtsZ resembles _____ in eukaryotes.

A

tubulin

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9
Q

The _____ of gram-negative bacteria is located on the outer leaflet; the inner leaflet contains _____.

A

lipopolysaccharide (LPS); phospholipids

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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

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11
Q

What is the internal osmotic pressure for a gram-positive bacterium?

A

about 20 atm

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12
Q

What is another name for pili?

A

fimbriae

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12
Q

What is the death phase?

A

a decrease in the number of viable bacteria

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12
Q

Which drugs inhibit nucleic acid synthesis?

A

1) quinolones 2) rifampicin

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13
Q

____ and ____ resemble actin in eukaryotes.

A

MreB; ParM

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14
Q

In gram-negative bacteria, the tetrapeptides are cross-linked from DAP to ____.

A

D-ala

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15
Q

Which drug inhibits RNA polymerase and interferes with transcription initiation?

A

rifampicin

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16
Q

Most capsular polysaccharides are _____, and some are used as vaccine components.

A

antigenic

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16
Q

How does vancomycin work?

A

inhibits the utilization of lipid-linked intermediate in peptidoglycan synthesis

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17
Q

What does polycistronic mean?

A

encode for more than one protein product

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18
Q

Bacterial mRNAs may be _____.

A

polycistronic

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19
Q

What is the lag phase?

A

when the bacteria are “adjusting” by inducing new enzymes and establishing a proper intracellular environment

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20
Q

_____ consists of a polymer of repeating units of 2 hexose sugars, N-acetylglucosamine (GlcNAc) and N-acetylmuramic (MurNAc) acid.

A

Peptidoglycan

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21
Q

Heterotrophic bacteria obtain both ____ and _____ by subjecting nutrients to fermentation and respiration.

A

energy; reducing power

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22
Q

Lipoteichoic acids are attached to _____ and help _____.

A

the underlying cytoplasmic membrane; anchor the cell wall to the membrane

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22
Q

What is another name for the bacterial cytoplasmic membrane?

A

inner membrane (in gram-negative bacteria)

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22
Q

What is the purpose of the cytoplasmic membrane?

A

it’s the barrier btw the inside and outside of the bacterial cell

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22
Q

Which drug interferes with folate metabolism by inhibiting dihydrofolate reductase?

A

trimethoprim

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23
Q

Lipopolysaccharide (LPS) contains lipid A, core polysaccharide, and _____.

A

O side chain oligosaccharides

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23
Q

If the environment remains favorable, bacteria are capable of _____ growth and division.

A

unlimited

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23
Q

What is selective toxicity?

A

using a drug concentration that affects the bacteria and is tolerated by the host

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23
Q

What drugs binds to the 50S ribosomal subunit and inhibits peptidyl transferase and peptide bond formation?

A

chloramphenicols

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23
Q

_____ are structural analogs of p-aminobenzoic acid (PABA), which is a component of folic acid.

A

Sulfonamides

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24
Q

Which drug inhibits alanine racemace, preventing the formation of muramyl pentapeptide in the peptidoglycans?

A

cycloserine

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25
Q

____ have a thick, extensively cross-linked peptidoglycan layer that also contains teichoic acids.

A

Gram-positive bacteria

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26
Q

Which drug inhibits the utilization of lipid-linked intermediate in peptidoglycan synthesis?

A

vancomycin

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27
Q

What is sporulation?

A

generation of spores because of a lack of C, N, or P

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28
Q

What is phage conversion?

A

a change in the phenotype of a host bacterium as a consequence of gene expression encoded by a bacteriophage

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29
Q

Sulfonamides are structural analogs of _____, which is a component of folic acid.

A

p-aminobenzoic acid (PABA)

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30
Q

How do the macrolides and lincomycins work?

A

bind to the 23S ribosomal RNA and the 50S subunit and inhibit peptidyl transferase

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32
Q

The lipopolysaccharide (LPS) of gram-negative bacteria is located _____; the ______ contains phospholipids.

A

on the outer leaflet; inner leaflet

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32
Q

Describe the bacterial chromosome.

A

usually a single, double-stranded, circular DNA molecule (but can be linear or multiple)

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33
Q

In gram-positive bacteria, the tetrapeptides are cross-linked from L-lys to ____ with an intervening peptide such as pentaglycine.

A

D-ala

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35
Q

What is peptidoglycan made of?

A

a polymer of repeating units of 2 hexose sugars, N-acetylglucosamine (GlcNAc) and N-acetylmuramic (MurNAc) acid

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36
Q

What is fermentation?

A

organic compounds serve as both e- donors and acceptors; no net oxidation of substrates; usu anaerobic conditions

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37
Q

Teichoic acid, found in gram-positive bacteria, has a repeating _____ backbone covalently attached to the peptidoglycan layer.

A

polyglycerol-P or polyribitol-P

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37
Q

Counterclockwise flagellar motion results in ____; clockwise results in _____.

A

swimming; tumbling

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37
Q

What drug binds to the 30S ribosome and inhibits binding of aminoacyl tRNA?

A

tetracyclines

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39
Q

_____ have a thin, sparsely cross-linked peptidoglycan layer and other major components located exterior to it.

A

Gram negative bacteria

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40
Q

How does cycloserine work?

A

inhibits alanine racemace, preventing the formation of muramyl pentapeptide in the peptidoglycans

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42
Q

Gram-positive bacteria have a thick, extensively cross-linked peptidoglycan layer that also contains ____.

A

teichoic acids

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43
Q

What are the 2 forms of energy currency in the bacterial cell? What enzyme interconverts them?

A

1) ATP 2) electrochemical gradients (proton motive force) — membrane ATPase

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44
Q

Which drug is a cationic surfactant that disrupts the outer and cytoplasmic membrane?

A

polymyxins

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45
Q

How is trimethoprim selective?

A

bacteria are 50,000 times more sensitive to it than the host

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46
Q

What are the functions of the cytoplasmic membrane? (5)

A

1) electron transport system 2) transport of metabolites 3) biosynthesis of lipids 4) DNA replication 5) flagellar rotation

47
Q

Plasmids in pathogenic bacteria often encode _____; _____ carry genes that determine resistance to antibiotics.

A

virulence factors; R-factors

48
Q

What are capsules?

A

loose, gelatinous outer surface layers consisting of complex polysaccharides that enhance virulence

49
Q

_____ play a role in bacterial conjugation.

A

Sex pilli

51
Q

Where does lysozyme cleave the peptidoglycan?

A

the glycosidic bond between MurNAc and GlcNAc

52
Q

What is the nucleoid?

A

a distinct region of the cytoplasm where the DNA of bacteria is located

53
Q

The ____ phase is when the bacteria are “adjusting” by inducing new enzymes and establishing a proper intracellular environment .

A

lag

55
Q

The _____ is typically much greater in gram-positive bacteria.

A

extent of cross-linking

55
Q

What drugs target the outer and cytoplasmic membrane?

A

polymyxin

56
Q

What are obligate intracellular bacteria?

A

bacteria that can only grow within a eukaryote

58
Q

Teichoic acid, found in _____, has a repeating polyglycerol-P or polyribitol-P backbone covalently attached to the peptidoglycan layer.

A

gram-positive bacteria

59
Q

Lipopolysaccharide (LPS) contains _____, core polysaccharide, and O side chain oligosaccharides.

A

lipid A

60
Q

What are polyribosomes?

A

several ribosomes interacting with a single mRNA

62
Q

What enzyme hydrolyzes peptidoglycan?

A

lysozyme

63
Q

These residues are linked to tetrapeptide chains that contain aas only found in bacterial cell walls.

A

N-acetylmuramic (MurNAc)

64
Q

_____ forms a rigid mesh that surrounds the cytoplasmic membrane.

A

Peptidoglycan

64
Q

In gram-negative bacteria, the tetrapeptides are cross-linked from ____ to D-ala.

A

DAP

65
Q

What drug inhibits lipid synthesis in Mycobacteria?

A

isoniazid

66
Q

How does metronidazole work?

A

interferes with anaerobic metabolism

68
Q

What does peptidoglycan do?

A

it surrounds the cytoplasmic membrane and forms a rigid mesh

69
Q

MreB and ParM resemble ____ in eukaryotes.

A

actin

70
Q

How do capsules enhance virulence?

A

they enable the bacteria to resist phagocytosis

70
Q

What drug interferes with anaerobic metabolism?

A

metronidazole

71
Q

What are the 4 distinct phases of the bacterial growth curve?

A

1) lag phase 2) exponential/logarithmic phase 3) stationary phase 4)

73
Q

What organelles/cellular components do bacteria have, as opposed to eukaryotes?

A
  1. cell wall (peptidoglycan) 2. 70S ribosome
74
Q

What are the bacterial 70S ribosomes related to?

A

eukaryotic mitochondria

75
Q

The DNA genomes of _____ can integrate into bacterial chromosomes and often carry genes that encode bacterial toxins, virulence factors, or resistance to antibiotics.

A

temperate bacteriophages

76
Q

What is a plasmid?

A

an extra-chromosomal, self-replicating DNA molecule usu not essential for bacterial viability

78
Q

Name 3 bacterial cytoskeletal structural elements.

A

1) FtsZ 2) MreB 3) CreS

79
Q

Which drugs bind to the 23S ribosomal RNA and the 50S subunit and inhibit peptidyl transferase?

A

macrolides and lincomycins

80
Q

What is the stationary phase?

A

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
Q

How do quinolones work?

A

inhibit DNA gyrase and topoisomerase

83
Q

_____ distribution means the flagella are on one end of the cell.

A

Polar

85
Q

The distinct region of the cytoplasm where the DNA of bacteria is located is called the ____.

A

nucleoid

87
Q

What ribosomes do bacteria have?

A

70S

88
Q

Most flagella are antigenic, and the _____ used to classify enteric bacteria are flagellar antigens.

A

H antigens

88
Q

What are the minimum requirements for growth for most bacteria?

A

nutrient medium containing inorganic ions, a carbon source, and an energy source

90
Q

Why does a bacterium have a rigid cell wall?

A
  1. to resist osmotic lysis 2. to maintain cell shape
90
Q

What is the generation time?

A

doubling time

91
Q

The outer membrane of gram-negative bacteria contains _____, _____, and _____.

A

lipopolysaccharides; lipoproteins; porins

93
Q

Name 3 amino acids found only in bacterial cell walls.

A
  1. meso-diaminopimelic acid (DIP) 2. D-glutamic acid 3. D-alanine
94
Q

_____ flagellar motion results in swimming; _____ results in tumbling.

A

Counterclockwise; clockwise

96
Q

What do antibodies to pili do?

A

block bacterial adherence and confer resistance to infection

97
Q

_____ are important for bacterial chemotaxis.

A

Flagella

97
Q

What is an extra-chromosomal, self-replicating DNA molecule usu not essential for bacterial viability called?

A

a plasmid

98
Q

What is the internal osmotic pressure in a gram-negative bacterium?

A

about 5 atm

100
Q

What are autotrophic bacteria?

A

bacteria that obtain their C exclusively from CO2

101
Q

Which drugs bind to target proteins on the 30S ribosome to inhibit protein synthesis?

A

aminoglycosides

102
Q

Name 4 drugs that inhibit metabolism in bacteria.

A

1) sulfonamides 2) trimethoprim 3) isoniazid 4) metronidazole

104
Q

How is the cytoplasmic membrane different than the plasma membrane of animal cells?

A
  1. usually contains no sterols 2. has a much higher protein content (60-70%)
105
Q

What is N-acetylmuramic (MurNAc)?

A

a hexose sugar that makes up peptidoglycan; is linked to tetrapeptide chains that contain aas that are only found in bacterial cell walls

106
Q

______ is determined by both intracellular cytoskeletal elements and by rigid components of the cell wall.

A

Bacterial cell shape

106
Q

Which drug inhibits the final transpeptidation rxn in cross-linking peptidoglycan?

A

beta-lactam

107
Q

How do beta-lactams work?

A

inhibit the final transpeptidation rxn in cross-linking peptidoglycan

108
Q

How does trimethoprim work?

A

interferes with folate metabolism by inhibiting dihydrofolate reductase

110
Q

What is the inoculum?

A

the starting cells

112
Q

What are the components of the bacterial cytoplasm? (3)

A

1) ribosomes 2) nucleoid 3) chromosome (plasmids)

113
Q

Where is the genetic material found in a bacterium?

A

in the cytoplasm

114
Q

Organisms that grow in the presence of O2 produce _____, such as ____ or _____.

A

toxic oxygen metabolites; hydrogen peroxide; superoxide

115
Q

What is N-acetylglucosamine (GlcNAc)?

A

a hexose sugar that makes up peptidoglycan

116
Q

What are porins?

A

transmembrane channels that allow hydrophilic molecules of

117
Q

How does rifampicin work?

A

inhibits RNA polymerase and interferes with transcription initiation

118
Q

Sulfonamides are structural analogs of p-aminobenzoic acid (PABA), which is a component of _____.

A

folic acid

120
Q

What organelles/cellular components do bacteria lack, as opposed to eukaryotes?

A
  1. a nuclear membrane 2. ER 3. mitotic spindle 4. mitochondria 5. chloroplasts
121
Q

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.

A

stationary

122
Q

In gram-positive bacteria, the tetrapeptides are cross-linked from L-lys to D-ala with an intervening peptide such as ______.

A

pentaglycine

124
Q

Bacterial cell shape is determined by both_____ and by _____.

A

intracellular cytoskeletal elements; rigid components of the cell wall

126
Q

What does the cytoplasmic membrane consist of?

A

a lipid bilayer of phospholipids and proteins

127
Q

How do aminoglycosides work?

A

bind to target proteins on the 30S ribosome to inhibit protein synthesis

128
Q

Gram negative bacteria have a _____ and other major components located exterior to it.

A

thin, sparsely cross-linked peptidoglycan layer

129
Q

How do bacterial cells divide?

A

binary fission

130
Q

The extent of cross-linking is typically much greater in _____.

A

gram-positive bacteria

132
Q

Which drugs target the peptidoglycan?

A

1) beta-lactams 2) vancomycin 3) cycloserine

133
Q

What is Lipid A?

A

the toxic component of endotoxin

135
Q

What are fastidious bacteria?

A

bacteria that need growth factors like aas, vitamins, purines, pyrimidines, and inorganic ions

136
Q

Heterotrophic bacteria obtain both energy and reducing power by subjecting nutrients to _____ and _____.

A

fermentation; respiration

137
Q

What is anaerobic respiration?

A

bacteria using inorganic substrates such as nitrate or nitrite as the terminal e- acceptor

138
Q

There is no ____ surrounding the bacterial DNA.

A

nuclear membrane

139
Q

What is a change in the phenotype of a host bacterium as a consequence of gene expression encoded by a bacteriophage called?

A

phage conversion

140
Q

Name 5 major antibacterial targets.

A

1) cell walls (peptidoglycan) 2) outer and cytoplasmic membrane 3) protein synthesis at the ribosome 4) nucleic acid synthesis 5) metabolic inhibition

142
Q

CreS appears to function like _____ in eukaryotes.

A

intermediate filaments

143
Q

How do sulfonamides work?

A

inhibit the formation of folic acid, preventing nucleic acid synthesis

145
Q

How does polymyxin work?

A

it’s a cationic surfactant that disrupts the outer and cytoplasmic membranes

146
Q

____, found in gram-positive bacteria, has a repeating polyglycerol-P or polyribitol-P backbone covalently attached to the peptidoglycan layer.

A

Teichoic acid

147
Q

During sporulation, bacteria differentiate to form _____ that have no _____.

A

highly resistant, dehydrated forms (spores); metabolic activity

148
Q

Bacteria that grow in the presence of O2 produce ______ or ______ that protect them against toxic ROS.

A

catalase/peroxidase, superoxide dismutase (SOD)

149
Q

Which drug inhibits DNA gyrase and topoisomerase?

A

quinolones

150
Q

Flagella can be ____ or ____ in their distribution.

A

peritrichous; polar

151
Q

_____ are attached to the underlying cytoplasmic membrane and help anchor the cell wall to the membrane.

A

Lipoteichoic acids

152
Q

How are sulfonamides selective?

A

bacteria cannot utilize pre-formed folic acid (humans can) and synthesize folic acid on their own (humans do not)

153
Q

Because there is no nuclear membrane, _____ can occur in bacteria.

A

transcription and translation can occur as a coupled process

154
Q

______ distribution means the flagella are all over the surface.

A

Peritrichous

155
Q

What are heterotrophic bacteria?

A

bacteria requiring an organic carbon source

156
Q

What drugs are inhibitors of protein synthesis at the ribosome?

A

1) aminoglycosides 2) tetracyclines 3) chloramphenicol 4) macrolides

157
Q

____ resembles tubulin in eukaryotes.

A

FtsZ

Lindsey's D&D Unit 3 (12 decks)

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