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Genetics > Chapter Eighteen: Gene Regulation in Prokaryotes > Flashcards

Chapter Eighteen: Gene Regulation in Prokaryotes Flashcards

(111 cards)

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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
splits lactose into glucose and galactose
beta-galactosidase
26
lactose is a disaccharide of ___ and ___
glucose and galactose
27
are permease and B-gal present when lactose is not present
yes, in very low levels
28
lactose is an ___ of the genes encoding permease and B-Gal
inducer
29
stimulation of the synthesis of a specific promoter
induction
30
molecule responsible for induction
inducer
31
lac- mutants can be maintained on media with ___, so lac genes are not ___ for survival
glucose essential
32
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 ___
glucose glucose broken down
33
lactose induces a ___ increase in B-gal activity
1000 fold
34
studies of lac mutants revealed the ___ of gene regulation
operon theory
35
one signal can simultaneously regulate expression of several clustered genes
operon theory
36
three structural genes in the lac operon
lacZ, lacY, and lacA
37
site to which RNA polymerase binds
promoter
38
controls transcription and translation
operator
39
in the absence of lactose, a ___ binds to the ___ and functions to ___
repressor protein operator prevent transcription
40
the lac repressor is a ___ regulatory element
negative
41
when lactose is present, it binds to the ___, which moves off of the ___ because it ___; this allows for ___
repressor protein operator changes shape transcription of the structural genes
42
type of repressor that reversibly changes shape and cannot bind to operator
allosteric repressor
43
when lactose is bound to the repressor protein, RNA polymerase binds to the ___ and initiates ___ of the ___ lac mRNA
promoter transcription polycistronic
44
lacZ encodes ___
B-galactosidase
45
lacY encodes ___
permease
46
lacA encodes ___
transacetylase
47
lacI encodes ___
the repressor protein
48
a mutation in lacI that stops the repressor protein from being made causes ___ of the structural genes
constitutive expression
49
mutations of the lacO (operator) sequence would cause ___ of the structural genes
constitutive expression
50
lacIc mutants have a super repressor that binds to the ___ but cannot bind to the ___; causes ___ in the presence or absence of lactose
operator inducer repression
51
can diffuse through the cytoplasm and act at target DNA sites on any DNA molecule in the cell
trans-acting elements
52
can only influence expression of adjacent genes on the same DNA molecule
cis-acting elements
53
lacI+ proteins act in ___
trans
54
lacO acts in ___
cis
55
lacZYA are ___
polycistronic
56
lac repressor binds to the ___
operator
57
lac repressor domains correspond to ___
functions
58
operator and promoter can be identified by ___
DNAse footprinting
59
structure of operator and repressor allows for ___ in binding
cooperativity
60
the lac repressor ___ motif binds DNA
helix-turn-helix (HTH)
61
the HTH motif is found in hundreds of ___
DNA binding proteins
62
duplication and divergence means each HTH motif recognizes a ___
different DNA sequence
63
the lac repressor HTH motif recognizes the ___
lac operator
64
DNAse footprinting identified the DNA sequence bound by the ___
repressor
65
DNAse digests DNA not bound by a ___
protein
66
digesting DNA not bound to protein forms ___ on a gel, with a break occurring when ___
bands bound proteins protect the DNA from digestion
67
when he lac repressor is bound to the lac operator, functional binding of ___ to ___ is blocked
RNA polymerase to promoter
68
lac repressor tetramer binds to ___
two sites
69
the lac operon has ___ operators, each of which contains two recognition sequences for ___
three lac repressor
70
___ has the strongest binding affinity for lac repressor
O1
71
maximal repression occurs when ___
all four repressor subunits are bound
72
___ repressor subunits bind to O1
two
73
two repressor subunits bind to either ___ or ___
O2 or O3
74
the lac operon of E. coli is regulated by both ___ and ___
lactose and glucose
75
when both lactose and glucose are present, only ___ is utilized
glucose
76
lactose induces ___ expression, but only in the ___ of glucose
lac mRNA absence
77
lactose prevents ___ from binding to ___
repressor lacO (operator)
78
lac repressor is a ___ regulator of lac transcription
negative
79
lac mRNA expression cannot be induced if ___ is present
glucose
80
in the absence of glucose, levels of ___ increase
cAMP
81
cAMP binds to ___
cAMP receptor protein (CRP)
82
CRP-cAMP is a __ regulator of lac transcription
positive
83
CRP-cAMP complex makes ___ with RNA polymerase
direct contact
84
without interaction from CRP-cAMP, RNA polymerase can ___ but is less likely to ___
bind the promoter unwind the DNA and initiate transcription
85
overall effect of glucose is to prevent ___
lac gene expression
86
anabolic synthesis of tryptophan (trp) is regulated by the ___
trp operon
87
structural genes for tryptophan (trp) biosynthesis are expressed only ___
in the absence of trp
88
transcription from the trp promoter produces two ___
alternative transcripts
89
tryptophan acts as a ___
corepressor
90
binding of trp to TrpR repressor allows ___ to bind to ___ and inhibit transcription of the five structural genes
TrpR TrpO
91
in the absence of trp, TrpR repressor cannot ___
bind to TrpO to induce transcription
92
gene regulation after transcription ignition occurs by several ___
RNA-based mechanisms
93
RNA leader sequences act in ___
cis
94
small RNAs (sRNA) act in ___
trans
94
two examples of RNA leader sequences
attenuation riboswitches
95
after transcription initiation, RNA ___ can regulate gene expression
structure
96
controls termination of transcription in the trp leader
attenuation
97
when trp is present, transcription ___ in the trp leader; when trp is absent, transcription ___ in the trp leader
terminates doesn't terminate
98
RNA leader sequence forms alternate ___ structures
stem loop
99
the ___ is a transcription terminator; the ___ prevents formation of the ___, so it is an antiterminator
3-4 stem loop 2-3 stem loop 3-4 stem loop
100
a terminator may halt ___ or prevent access to the ___
transcription ribosome
101
when trp is present, transcription ___ due to the formation of ___
terminates 3-4 stem loop
102
movement of ribosomes depends on the availability of ___
tRNAtrp
103
when trp is present, tRNAtrp is ___ and ___ ribosome movement allows for formation of a ___
available rapid 3-4 stem loop
104
riboswitches bind ___ to regulate ___
small molecules gene expression
105
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
several conformations aptamer expression platform
106
small RNAs usually ___ translation by ___
inhibit base-pairing with the ribosome site
107
small RNAs can also ___ transcription by disrupting ___
activate stem loops
108
some small RNAs lead to mRNA ___
degradation
109
___ is produced by transcription of the strand of DNA opposite the template strand
antisense RNA
110
antisense RNA may ___ translation by base pairing with the sense strand
inhibit

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