Chapter Sixteen: Bacterial Genes Flashcards

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1
Q

an adult human carries ___ bacteria, which is about the same as the number of human cells

A

30-50 trillion

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2
Q

most bacteria are in the ___, but they are also found in the ___, ___, and ___

A

intestines
skin, mouth, and respiratory tracts

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3
Q

___ are common for people with intestinal bacteria issues

A

fecal transplants

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4
Q

bacteria are ___ to ___ in length

A

200nm to 500micrometers

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5
Q

bacteria lack a ___ and ___

A

nucleus and membrane bound organelles

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6
Q

bacteria store their DNA in a single ___ folded into a ___

A

chromosome
nucleoid body

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7
Q

most bacteria have a ___, and some antibiotics inhibit ___ because human cells don’t have this characteristic

A

cell wall
cell wall synthesis

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8
Q

bacteria have adapted to a ___ of habitats

A

range

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9
Q

four possible habitats for bacteria

A
  1. on land
  2. in aquatic environments
  3. parasites
  4. symbionts inside another life form
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10
Q

bacterial ___ must be adapted to its environment

A

metabolism

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11
Q

some bacteria obtain energy from ___, others from ___

A

ammonia
sunlight

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12
Q

three natural processes that bacteria play a role in

A
  1. decomposition of materials for nutrient cycling
  2. important in nitrogen cycling
  3. some eat oil
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13
Q

bacteria that eat oil

A

bioremediation bacteria

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14
Q

a ___ fraction of bacteria is pathogenic

A

small

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15
Q

pathogenic bacteria invade ___ and produce ___

A

tissues
toxins

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16
Q

proteins that interfere with cell function or destroy cells

A

toxins

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17
Q

toxin that results in paralysis by interfering with communication between nerves and muscles

A

tetanus toxin

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18
Q

pretty much any bacteria that gets ___ will kill you

A

into your blood (septic)

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19
Q

the typical bacterial genome is composed of ___

A

one circular chromosome

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20
Q

there are ___ of DNA in most common studied bacteria

A

4-5Mb

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21
Q

the DNA molecule condenses by ___ and ___

A

supercoiling and looping

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22
Q

each bacterium replicates its chromosome and then divides by ___ into two daughter cells

A

binary fission

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23
Q

bacterial genomes are ___ with genes

A

tightly packed

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24
Q

___ of E. coli DNA encodes proteins; ___ of human DNA encodes proteins

A

90%
5%

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25
Q

E. coli have no ___ in their genome

A

introns

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26
Q

E. coli K12 genome has ___ genes

A

4288

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27
Q

genomes of ___ of E. coli strains have been sequences

A

100s

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28
Q

genes that are found in all strains of a species

A

core genome

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29
Q

there are about ___ core genes for E. coli

A

1000

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30
Q

functions of core genes

A

characteristics of life: nutrient assimilation, metabolism, waste removal, responding to environment, transcription and translation, replication, etc.

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31
Q

core genome plus all genes that are found in some strains of a species but not others

A

pangenome

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32
Q

the E. coli pangenome consists of about ___ genes

A

15,000

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33
Q

do bacterial genes contain transposons

A

yes

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34
Q

small bacterial transposons that do not contain selectable markers

A

insertion sequences (IS)

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35
Q

like the ends of DNA transposons in eukaryotic cells, the ends of IS elements are ___

A

inverted repeats of each other

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36
Q

each insertion sequence includes a gene that encodes ___

A

transposase

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37
Q

insertion sequences can disrupt ___

A

gene function

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38
Q

IS can rearrange bacterial genomes by causing ___ or ___

A

deletions or inversions

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39
Q

a bacterial transposon carrying transposase and drug resistance genes flanked by ISs

A

Tn elements

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40
Q

___ carry additional DNA

A

plasmids

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41
Q

plasmids are small circles of ___

A

double stranded DNA

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42
Q

plasmids are used as ___

A

cloning vectors

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43
Q

plasmids may contain genes that ___ or ___

A

benefit host bacterium or contribute to bacterial pathogenicity

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44
Q

plasmids that provide resistance to antibiotics

A

resistance plasmids

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45
Q

antibiotic resistance is often due to the presence of ___ on a plasmid

A

composite IS/Tn transposons

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46
Q

resistance plasmids can be transferred from ___ to ___ in nature easily

A

one bacteria to another

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47
Q

resistance plasmids are ___ for humans taking antibiotics

A

not good

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48
Q

the collective analysis of genomic DNA from an entire community of microbes

A

metagenomics

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49
Q

the initiative to identify all species of microorganisms that are symbionts with humans, and to correlate differences in microorganism populations with phenotypic differences and disease states

A

human microbiome project

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50
Q

there have been ___ species of bacteria identified in the human microbiome project

A

10,000

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51
Q

individuals vary in ___ of bacteria they carry

A

species

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52
Q

proteins that work under unusual conditions

A

extremophiles

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53
Q

a type of extremophile DNA polymerase

A

Taq DNA polymerase

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54
Q

extremophile bacteria that grow well in high pH have enzymes that are used in ___

A

laundry detergents

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55
Q

bacteria must be grown and studied in ___

A

cultures

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56
Q

bacteria are grown as ___ in liquid media

A

cell suspension

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57
Q

bacteria are grown as ___ on solid nutrient agar plates

A

colonies

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58
Q

the most studied and best understood bacterial species

A

E. coli

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59
Q

E. coli normally inhabits ___

A

intestines of warm-blooded animals

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60
Q

E. coli can grow in the complete absence of ___ or in ___

A

oxygen
air

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61
Q

lab strains of E. coli are not ___, but other strains can cause ___

A

pathogenic
intestinal diseases

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62
Q

E. coli are ___, meaning they can grow in minimal media

A

phototrophic

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63
Q

E. coli cells divide every ___

A

20 minutes

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64
Q

most bacteria carry ___ copy of each gene, making them ___

A

one
monoploid

65
Q

because bacteria are monoploid, all mutations express ___

A

their phenotype

66
Q

five categories of bacterial mutants

A
  1. affect colony morphology
  2. affect resistance to bactericides
  3. create auxotrophs
  4. affect catabolism
  5. affect essential genes
67
Q

unable to reproduce in minimal media

A

auxotroph

68
Q

mutations that create auxotrophs produce defective ___ that are required to synthesize complex compounds needed to survive

A

enzymes

69
Q

a process that establishes conditions in which only the desired mutant will grow

A

genetic selection

70
Q

a process in which colonies are examined for a particular phenotype

A

genetic screen

71
Q

genes of bacteria specified by three lowercase italicized letters refer to the ___ of the gene

A

function

72
Q

leuA, leuB, leuC, and leuD are genes that encode enzymes needed to synthesize ___

A

leucine

73
Q

wild-type alleles are designated with ___ and mutant alleles are designated with ___

A
74
Q

the passing or transferring of genes from parent to offspring, occurs in sexually reproducing organisms

A

vertical gene transfer

75
Q

the introduction and incorporation of DNA from an unrelated individual or from a different species

A

horizontal gene transfer

76
Q

three mechanisms for gene transfer in bacteria

A
  1. transformation
  2. conjugation
  3. transduction
77
Q

bacterium that provides the DNA that is being transferred

A

donor

78
Q

bacterium that receives the DNA, which can result in an altered phenotype

A

recipient

79
Q

competent cells can take up DNA fragments from surrounding environment

A

transformation

80
Q

when bacteria take up DNA fragments spontaneously from their environment

A

natural transformation

81
Q

DNA transfer that can be accomplished in the lab by making the cells competent

A

artificial transformation

82
Q

genes close together have a ___ of co-transformation than genes further apart

A

higher

83
Q

donor DNA is transferred directly to the recipient through a connecting tube

A

conjugation

84
Q

bacteria conjugation require ___

A

cell-to-cell contact

85
Q

the ___ contains genes for synthesizing connections between donor and recipient cells

A

F plasmid

86
Q

donors for conjugation are F___, meaning they carry a ___

A

+
F plasmid

87
Q

recipients for conjugation are F___, meaning they do not carry a ___

A

-
F plasmid

88
Q

process of conjugation

A
  1. F pilus binds to F- cell wall
  2. pilus retracts and cells are drawn together
  3. gene transfer occurs
89
Q

after conjugation, both cells are ___ and can conjugate with other ___ cells

A

F+
F-

90
Q

F plasmid has three ___, which are identical to those found at various positions on the bacterial chromosome

A

IS elements

91
Q

formed when an F plasmid integrates into the bacterial chromosome through recombination between IS elements

A

high frequency recombinant (Hfr) cells

92
Q

an F plasmid that can integrate into the bacterial genome

A

episome

93
Q

Hfr strains differ in the ___ and ___ of the integrated episomes

A

location and orientation

94
Q

Hfr strains retain all ___ and can be a ___ for conjugation with an F- strain

A

F plasmid functions
donor

95
Q

transfer of DNA starts in the F plasmid at the ___

A

origin of transfer

96
Q

___ located next to F plasmid sequences are transferred to the recipient

A

chromosomal sequences

97
Q

transferred chromosomal DNA recombines into ___ in recipient

A

homologous DNA

98
Q

process of gene transfer between Hfr donors and F- recipients

A
  1. F plus of Hfr cell establishes connection with F-cell
  2. single strand of integrated F plasmid is cut
  3. Hfr chromosome replicates itself as transfer happens
  4. F plasmid followed by chromosomal DNA passes into recipient cell
  5. donor DNA is replicated in host cell
  6. cells separate
  7. crossover between homologous regions on donor and recipient DNA
  8. recipient cell remains F- but carries some genes from Hfr chromosome
99
Q

genes can be ___ by gene transfer during conjugation

A

mapped (located)

100
Q

the ___ experiment was used to map genes by gene transfer in conjugation

A

interrupted-mating experiment

101
Q

genes that immediately follow the origin of transfer in Hfr chromosome are ___

A

transferred first

102
Q

order of transfer reflects the ___

A

gene order on the chromosome

103
Q

a conjugative plasmid that carries many genes required for the transfer of DNA

A

F’ plasmid

104
Q

F’ plasmid is formed by excision of ___ and ___

A

F plasmid and some adjacent bacterial chromosomal DNA

105
Q

F’ plasmids replicate ___ in bacterial cells

A

independently

106
Q

F’ plasmids can be transferred to F- cells by ___

A

conjugation

107
Q

F’ plasmids can be used for ___ studies

A

complementation

108
Q

cells carrying the F’ plasmid are called ___; cells without the F’ plasmid are called ___

A

F+
F-

109
Q

conjugation of F- with F’ can make partial diploids called ___

A

merodiploids

110
Q

merodiploids are partial diploids that contain ___

A

two copies of some genes

111
Q

when assessing a mutation impacting tryptophan biosynthesis: if the merodiploid shown can grow without tryptophan, the two trp mutations are ___

A

in different genes

112
Q

a method of transfer in which donor DNA is packed into a bacteriophage and transferred into the recipient when the phage infects it

A

transduction

113
Q

phages are ___ in nature and most bacteria are susceptible to ___ phages

A

widely distributed
one or more

114
Q

phages that always enter the lytic cycle after infecting a cell

A

virulent phages

115
Q

phages that can enter either the lytic or lysogenic cycle after infecting a cell

A

temperate phages

116
Q

the bacterial cycle of phage-infected cells resulting in cell lysis and release of progeny phage

A

lytic cycle

117
Q

5 steps of the lytic cycle

A
  1. phage injects its DNA into bacterial cell
  2. phage proteins are expressed and take over protein synthesis and DNA replication machinery of infected cell
  3. phage DNA replication occurs
  4. phage particles are assembled with phage DNA and phage protein
  5. infected cell bursts and releases 100-200 new viral particles able to infect other cells
118
Q

the population of phage particles released from host bacteria at the end of the lytic cycle

A

lysate

119
Q

type of transduction that can result in the transfer of any bacterial gene between related strains of bacteria

A

generalized transduction

120
Q

generalized transduction is the incorporation of ___ of bacterial DNA from donor into bacteriophage particles

A

random fragments

121
Q

transfer of different bacterial genes together in one phage by transduction

A

cotransduction

122
Q

frequencies of cotransduction depends directly on ___

A

the distance between the two genes

123
Q

cotransduction frequencies are ___ for genes that are close together and ___ for genes that are further apart

A

higher
lower

124
Q

for temperate phages, the choice between lytic or lysogenic phage depends on ___

A

many factors, including environmental conditions

125
Q

bacteria that harbor in an integrated temperate phage

A

lysogen

126
Q

temperate phage that has integrated into host chromosome

A

prophage

127
Q

temperate phage commonly used in research

A

bacteriophage lambda

128
Q

prophages do not produce the ___ needed for ___

A

viral proteins
more viral particles

129
Q

lysogens can be induced to enter the ___

A

lytic cycle

130
Q

how does a lysogen enter the lytic cycle

A

prophage is excised from chromosome, undergoes replication, and then new virus particles form

131
Q

in some excisions of prophages, a small amount of ___ is excised with the prophage and packaged with viral DNA

A

bacterial genes adjacent to the prophage

132
Q

bacteriophage carrying mainly phage DNA but also one or a few of the bacterial genes that lie near the site of prophage insertion

A

specialized transduction phages

133
Q

bacteriophage-mediated transfer of a few bacterial genes located next to the prophage in the bacterial chromosome

A

specialized transduction

134
Q

integration of ___ initiates the lysogenic cycle

A

phage lambda DNA

135
Q

recombination between ___ on phage lambda and the bacterial chromosome allows integration of the prophage

A

att sites

136
Q

___ produces a specialized transducing phage

A

abnormal excision

137
Q

bacterial DNA adjacent to the integration site can be ___ with viral DNA and then ___ to recipient cell

A

packaged
transferred

138
Q

___ is an important mechanism for rapid adaptation to environmental changes

A

gene transfer

139
Q

genomic analysis has revealed ___ of gene transfer mechanisms in many bacterial species

A

widespread occurrence

140
Q

large DNA segments transferred from one bacterial species to another

A

genomic islands

141
Q

genomic islands originated from ___

A

horizontal gene transfer

142
Q

many genomic islands contain genes that encode ___ and ___

A

integration-like enzymes and genes that promote fitness of the recipient

143
Q

genes that promote fitness of the recipient are things like ___, ___

A

antibiotic resistant, metabolic enzymes

144
Q

segments of DNA in disease-causing bacteria that encode several genes involved in pathogenesis

A

pathogenicity islands

145
Q

Pathogenicity islands appear to have been transferred into the bacteria by horizontal gene transfer from a ___

A

different species

146
Q

pathogenicity islands came from the lateral transfer of a package of genes from a ___ to a ___

A

pathogenic species
nonpathogenic species

147
Q

can identify a mutant bacterial gene by ___ transformation

A

plasmid library

148
Q

to identify the mutant in an arginine auxotroph, transform mutant bacteria with ___, identify clones that grow ___

A

plasmid genomic library
without arginine

149
Q

gene ___ is used to make mutations in specific genes

A

targeting

150
Q

penicillin interferes with ___

A

synthesis of the bacterial cell wall

151
Q

penicillin binds to ___, inhibit its ___, and prevents ___

A

transpeptidase
enzymatic activity
cross-linking

152
Q

N. gonorrhoeae acquired a plasmid from H. influenzae that had the ___

A

penicillin resistance gene (penr)

153
Q

penr encodes ___

A

penicillinase

154
Q

penA encodes ___, a mutation in this decreases ___

A

transpeptidase
affinity for penicillin

155
Q

penB encodes ___, a mutation in this decreases ___

A

porin
entry of penicillin into cell

156
Q

a porin is a ___ that regulates ___

A

protein in the outer cell wall
entry into the periplasm

157
Q

mtr encodes ___, a mutation in this increases ___

A

repressor of an efflux pump
pumping of penicillin out of the cell

158
Q

three things that combat the problem of drug resistance

A
  1. reduce antibiotic use
  2. develop novel classes of antibiotics
  3. make existing antibiotics more effective
159
Q

MDRO stands for ___

A

multidrug resistant organism