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Genetics > Chapter Eighteen: Gene Regulation in Prokaryotes > Flashcards

Chapter Eighteen: Gene Regulation in Prokaryotes Flashcards

1
Q

bacteria are ___ and ___ their environment

A

in contact with and respond to

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2
Q

the ability to coordinate the expression of many genes leads to ___ and ___

A

survival and energy savings

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3
Q

luminescent bacteria protect squid from predators by controlling the ___

A

light level to match the moonlight

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4
Q

___ of ATP being used does into protein synthesis, don’t want to ___ when its not necessary

A

80%
make protein

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5
Q

___ participates in all three phases of prokaryotic transcription

A

RNA polymerase

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6
Q

in transcription initiation, RNA polymerase has four subunits (___, ___, and ___); ___ binds to RNA polymerase and recognizes the promoter site and also binds to it

A

two alpha, one beta, and one beta prime
sigma factor

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7
Q

in transcription elongation, RNA polymerase is not bound to ___, but moves along DNA until ___

A

sigma factor
it reaches a termination sequence

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8
Q

there are two kinds of termination in bacteria: ___ and ___

A

rho-dependent and rho-independent

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9
Q

in rho-dependent termination, ___ binds to RNA polymerase and ___

A

rho protein
removes it from RNA

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10
Q

in rho-independent termination, RNA forms a ___

A

hairpin loop

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11
Q

transcription and translation occur ___ in prokaryotes

A

simultaneously

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12
Q

sequences for start and stop of transcription are ___ from sequences for start and stop of translation

A

distinct

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13
Q

mRNA are often ___, meaning multiple genes together can be controlled by one promoter

A

polycistronic

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14
Q

three levels of transcriptional control

A
  1. binding of RNA polymerase to promoter
  2. shift from initiation to elongation
  3. release of mRNA at termination
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15
Q

three levels of posttranscriptional control

A
  1. stability of mRNA
  2. efficient of translation initiation
  3. stability of polypeptide
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16
Q

in a catabolic pathway, molecules are ___

A

broken down

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17
Q

catabolic pathways require ___

A

inducible regulation

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18
Q

inducible regulation means that the pathway is ___ when ___

A

only turned on when molecules to be broken down are present

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19
Q

in an anabolic pathway, molecules are ___

A

built from simpler constituents

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20
Q

anabolic pathways require ___

A

repressible regulation

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21
Q

repressible regulation means that the pathway is ___ unless the cell ___

A

turned off
needs more of the larger molecule

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22
Q

utilization of lactose by E. coli provides a model system of ___

A

gene regulation

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23
Q

two enzymes required for lactose utilization

A

permease and beta-galactosidase (B-gal)

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24
Q

transports lactose into cells

A

permease

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25
Q

splits lactose into glucose and galactose

A

beta-galactosidase

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26
Q

lactose is a disaccharide of ___ and ___

A

glucose and galactose

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27
Q

are permease and B-gal present when lactose is not present

A

yes, in very low levels

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28
Q

lactose is an ___ of the genes encoding permease and B-Gal

A

inducer

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29
Q

stimulation of the synthesis of a specific promoter

A

induction

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30
Q

molecule responsible for induction

A

inducer

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31
Q

lac- mutants can be maintained on media with ___, so lac genes are not ___ for survival

A

glucose
essential

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32
Q

if both glucose and lactose are present, E. coli cells will use ___ first; if there is a lot of ___ present, lactose does not need to be ___

A

glucose
glucose
broken down

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33
Q

lactose induces a ___ increase in B-gal activity

A

1000 fold

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34
Q

studies of lac mutants revealed the ___ of gene regulation

A

operon theory

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35
Q

one signal can simultaneously regulate expression of several clustered genes

A

operon theory

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36
Q

three structural genes in the lac operon

A

lacZ, lacY, and lacA

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37
Q

site to which RNA polymerase binds

A

promoter

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38
Q

controls transcription and translation

A

operator

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39
Q

in the absence of lactose, a ___ binds to the ___ and functions to ___

A

repressor protein
operator
prevent transcription

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40
Q

the lac repressor is a ___ regulatory element

A

negative

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41
Q

when lactose is present, it binds to the ___, which moves off of the ___ because it ___; this allows for ___

A

repressor protein
operator
changes shape
transcription of the structural genes

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42
Q

type of repressor that reversibly changes shape and cannot bind to operator

A

allosteric repressor

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43
Q

when lactose is bound to the repressor protein, RNA polymerase binds to the ___ and initiates ___ of the ___ lac mRNA

A

promoter
transcription
polycistronic

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44
Q

lacZ encodes ___

A

B-galactosidase

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45
Q

lacY encodes ___

A

permease

46
Q

lacA encodes ___

A

transacetylase

47
Q

lacI encodes ___

A

the repressor protein

48
Q

a mutation in lacI that stops the repressor protein from being made causes ___ of the structural genes

A

constitutive expression

49
Q

mutations of the lacO (operator) sequence would cause ___ of the structural genes

A

constitutive expression

50
Q

lacIc mutants have a super repressor that binds to the ___ but cannot bind to the ___; causes ___ in the presence or absence of lactose

A

operator
inducer
repression

51
Q

can diffuse through the cytoplasm and act at target DNA sites on any DNA molecule in the cell

A

trans-acting elements

52
Q

can only influence expression of adjacent genes on the same DNA molecule

A

cis-acting elements

53
Q

lacI+ proteins act in ___

A

trans

54
Q

lacO acts in ___

A

cis

55
Q

lacZYA are ___

A

polycistronic

56
Q

lac repressor binds to the ___

A

operator

57
Q

lac repressor domains correspond to ___

A

functions

58
Q

operator and promoter can be identified by ___

A

DNAse footprinting

59
Q

structure of operator and repressor allows for ___ in binding

A

cooperativity

60
Q

the lac repressor ___ motif binds DNA

A

helix-turn-helix (HTH)

61
Q

the HTH motif is found in hundreds of ___

A

DNA binding proteins

62
Q

duplication and divergence means each HTH motif recognizes a ___

A

different DNA sequence

63
Q

the lac repressor HTH motif recognizes the ___

A

lac operator

64
Q

DNAse footprinting identified the DNA sequence bound by the ___

A

repressor

65
Q

DNAse digests DNA not bound by a ___

A

protein

66
Q

digesting DNA not bound to protein forms ___ on a gel, with a break occurring when ___

A

bands
bound proteins protect the DNA from digestion

67
Q

when he lac repressor is bound to the lac operator, functional binding of ___ to ___ is blocked

A

RNA polymerase to promoter

68
Q

lac repressor tetramer binds to ___

A

two sites

69
Q

the lac operon has ___ operators, each of which contains two recognition sequences for ___

A

three
lac repressor

70
Q

___ has the strongest binding affinity for lac repressor

A

O1

71
Q

maximal repression occurs when ___

A

all four repressor subunits are bound

72
Q

___ repressor subunits bind to O1

A

two

73
Q

two repressor subunits bind to either ___ or ___

A

O2 or O3

74
Q

the lac operon of E. coli is regulated by both ___ and ___

A

lactose and glucose

75
Q

when both lactose and glucose are present, only ___ is utilized

A

glucose

76
Q

lactose induces ___ expression, but only in the ___ of glucose

A

lac mRNA
absence

77
Q

lactose prevents ___ from binding to ___

A

repressor
lacO (operator)

78
Q

lac repressor is a ___ regulator of lac transcription

A

negative

79
Q

lac mRNA expression cannot be induced if ___ is present

A

glucose

80
Q

in the absence of glucose, levels of ___ increase

A

cAMP

81
Q

cAMP binds to ___

A

cAMP receptor protein (CRP)

82
Q

CRP-cAMP is a __ regulator of lac transcription

A

positive

83
Q

CRP-cAMP complex makes ___ with RNA polymerase

A

direct contact

84
Q

without interaction from CRP-cAMP, RNA polymerase can ___ but is less likely to ___

A

bind the promoter
unwind the DNA and initiate transcription

85
Q

overall effect of glucose is to prevent ___

A

lac gene expression

86
Q

anabolic synthesis of tryptophan (trp) is regulated by the ___

A

trp operon

87
Q

structural genes for tryptophan (trp) biosynthesis are expressed only ___

A

in the absence of trp

88
Q

transcription from the trp promoter produces two ___

A

alternative transcripts

89
Q

tryptophan acts as a ___

A

corepressor

90
Q

binding of trp to TrpR repressor allows ___ to bind to ___ and inhibit transcription of the five structural genes

A

TrpR
TrpO

91
Q

in the absence of trp, TrpR repressor cannot ___

A

bind to TrpO to induce transcription

92
Q

gene regulation after transcription ignition occurs by several ___

A

RNA-based mechanisms

93
Q

RNA leader sequences act in ___

A

cis

94
Q

small RNAs (sRNA) act in ___

A

trans

94
Q

two examples of RNA leader sequences

A

attenuation
riboswitches

95
Q

after transcription initiation, RNA ___ can regulate gene expression

A

structure

96
Q

controls termination of transcription in the trp leader

A

attenuation

97
Q

when trp is present, transcription ___ in the trp leader; when trp is absent, transcription ___ in the trp leader

A

terminates
doesn’t terminate

98
Q

RNA leader sequence forms alternate ___ structures

A

stem loop

99
Q

the ___ is a transcription terminator; the ___ prevents formation of the ___, so it is an antiterminator

A

3-4 stem loop
2-3 stem loop
3-4 stem loop

100
Q

a terminator may halt ___ or prevent access to the ___

A

transcription
ribosome

101
Q

when trp is present, transcription ___ due to the formation of ___

A

terminates
3-4 stem loop

102
Q

movement of ribosomes depends on the availability of ___

A

tRNAtrp

103
Q

when trp is present, tRNAtrp is ___ and ___ ribosome movement allows for formation of a ___

A

available
rapid
3-4 stem loop

104
Q

riboswitches bind ___ to regulate ___

A

small molecules
gene expression

105
Q

a riboswitch is an RNA leader with ___, it binds small molecules through a short sequence called an ___, conformation of a second region called the ___ changes in response to first region configuration

A

several conformations
aptamer
expression platform

106
Q

small RNAs usually ___ translation by ___

A

inhibit
base-pairing with the ribosome site

107
Q

small RNAs can also ___ transcription by disrupting ___

A

activate
stem loops

108
Q

some small RNAs lead to mRNA ___

A

degradation

109
Q

___ is produced by transcription of the strand of DNA opposite the template strand

A

antisense RNA

110
Q

antisense RNA may ___ translation by base pairing with the sense strand

A

inhibit

Genetics (24 decks)

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