Chapter 14: Gene Regulation Prokaryotes Flashcards

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1
Q

gene regulation

A

process by which a cell controls whether an active protein is produced from a gene

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2
Q

gene regulation can occur at

A

many different levels of

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3
Q

gene expression

A

gene is transcribed into RNA
RNA translated into protein
protein is converted to the active form of the protein

dna - rna - protein- active protein

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4
Q

constitutive gene expression

A

the gene is expressed at the same level, all of the time, in all cell types

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5
Q

example of constitutive gene expression

A

housekeeping genes enzymes for glycolysis

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6
Q

regulated gene expression

A

many genes are expressed under certain conditions, in certain cell types, at certain developmental stages

at other times the gene is present but not used to make mRNA or protein (gene=off)

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7
Q

example of gene regulation in prokaryotes

A

enzymes for lactose metabolism are only expressed when lactose is present the media

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8
Q

examples of gene regulation in eukaryotes

A

genes that code for protective proteins are turned on when the organism is exposed to uv radiation

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9
Q

multicellular organisms undergo

A

cell differentiation

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10
Q

cell differentiation

A

when a cell becomes a specialized cell thpe

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11
Q

all cells have the same dna but

A

not all genes are expressed in every cell

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12
Q

in skeletal muscle cells, the striped look is from

A

actin and myosin

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13
Q

all cells contain the same ___
each cell type will contain different set of __
•some genes are
each cell type will contains different
• specialized cells ___ and ___

A

dna
rna
•turned on and others are turned off
protein
look different and have different functions

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14
Q

developmental gene expression

A

different genes are expressed in the
embryo, fetus, adult

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15
Q

in prokaryotes, Most gene regulation occurs at the level of

A

transcription

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16
Q

transcriptional regulation

A

controls whether dna is transcribed into rna

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17
Q

most common type of gene regulation in prokaryotes and eukaryotes

A

transcriptional regulation

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18
Q

in transcriptional regulation, rna is only made under certain conditions

A

if the gene is on: high levels of mRNA is made and protein will also be made
if the gene is off: no mRNA is made and no protein will be made

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19
Q

less common type of regulation in prokaryotes and eukaryotes

A

translational regulation

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20
Q

translational regulation

A

controls whether mRNA is used to make protein: mRNA is always made and mRNA is translated into protein only under certain conditions

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21
Q

posttranslational regulation

A

protein has been made
controls whether protein is in the active form (functional) or inactive form (nonfunctional)

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22
Q

common type of regulation of proteins in prokaryotes and eukaryotes

A

allosteric regulation
posttranslational

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23
Q

posttranslational regulation:
gene is always

what is or isn’t made?
form of protein

A

on= constitutive expression
rna is always made
protein is always made
protein can be in two different forms=allosteric regulation

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24
Q

posttranslational regulation: if protein is on
if protein is off

form
function

A

is is in the active form
of can perform its function in the cell

it is in the inactive form
the protein is nonfunctional and can’t do what it is designed to do

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25
Q

In eukaryotes, most gene regulation occurs at the level of

A

transcription

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26
Q

transcriptional regulation in eukaryotes

A

controls whether dna is transcribed into pre-mRNA

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27
Q

eukaryotes also have these types of regulation

A

transcriptional, translational, and posttranslational

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28
Q

regulation of RNA splicing

A

controls whether pre-mRNA is processed to a functional mRNA

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29
Q

what is only in eukaryotes?

A

regulation of RNA splicing

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30
Q

alternative splicing
1 pre-mRNA -> ___ protein

A

2
mRNA 1-> protein 1
mRNA 2-> protein 2

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31
Q

in transcriptional regulation genes can be turned

A

on and off

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32
Q

main way genes are regulated is through

A

transcriptional

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33
Q

in prokaryote transcriptional regulation, when a gene is turned on
level of transcription
mRNA
protein

A

very high level of transcription
large amounts of mRNA are made
large amounts of protein are made

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34
Q

in prokaryote transcriptional regulation, when a gene is turned off
level of transcription
mRNA
protein

A

very low level of transcription
very low or no mRNA is made
very low or no protein is made

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35
Q

transcription factor
binding

A

protein that controls whether the gene is transcribed into RNA
binds to DNA in the promoter of a gene
controls whether RNA polymerase can bind to the promoter

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36
Q

types of transcription factors

A

repressors
activators

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37
Q

repressors

A

protein that bind to the promoter of a gene and prevent rna synthesis

either completely blocks it or is like a road block and can’t move past it

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38
Q

when a repressor binds to the promoter,

A

it prevents RNA polymerase from binding to the promoter

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39
Q

if RNA polymerase can’t bind -> ___ mRNA-> __ proteins

A

no
no

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40
Q

what size is RNA polymerase

A

very large

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41
Q

negative control of gene expression

A

depressor binds to DNA and prevent or decrease amount of transcription from a gene

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42
Q

activators

A

proteins that bind near the promoter of a gene and increase or promote RNA synthesis

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43
Q

activators: some genes have ___ promoters so

A

weak
RNA polymerase can’t recognize and bind to these weak promoters efficiently by itself

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44
Q

activator binding process

A

the activator binds to a dna sequence near the promoter
helps the RNA polymerase bind to the promoter
once the RNA polymerase binds to the promoter it makes mRNA

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45
Q

positive control transcription factors

A

activator proteins increase the amount of transcription from a gene

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46
Q

no activator= polymerase ____ bind

A

can’t

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47
Q

the active form of a transcription factor is the form that

A

can bind to DNA and perform its function

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48
Q

the form of a transcription factor is controlled by an

A

effector molecule

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49
Q

effector molecule

A

small molecule that binds to the transcription factor and changes its shape (allosteric regulation)

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50
Q

active form of a repressors

A

the form of a repressor protein that can bind to dna and prevent transcription

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51
Q

active form of an activator

A

the form of a activator protein that can bind to dna and promote transcription

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52
Q

the inactive form of a transcription factor can

A

not bond to dna so does not carry out its function

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53
Q

inactive form of a repressor

A

can not bind to dna so does not prevent transcription
rna is made

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54
Q

inactive form of a activator

A

can not bind to dna so does not promote transcription
rna is not made

55
Q

in bacteria genes involved in the same process or pathway are sometimes clustered into an

A

operon

56
Q

operon

A

promoter + 2 or more coding regions

57
Q

bacterial genes are in

A

operons

58
Q

promoter

A

controls when genes in the operon are transcribed into RNA

59
Q

promoters consist of

A

LacP and regulatory regions = operon and cap site

60
Q

conserved dna sequences are binding sites for
where are the sequences at?

A

transcription factors
promoter

61
Q

binding site for DNA polymerase

A

lacP

62
Q

sigma factor binds to ___ and ____ sequences

A

-35
-10

63
Q

RNA polymerase binds to ____ and begins

A

sigma factor
transcription =RNA synthesis

64
Q

weak promoter has

A

changed sequences

65
Q

transcription factors can’t bind to

A

changed DNA

66
Q

structural genes

A

codes for an enzyme or protein
a number of genes all controlled by the one promoter
each gene codes for a different enzyme or protein involved in the process

67
Q

what are the structural genes names

A

lacZ
lacY
lacA

68
Q

an operon is transcribed into a

A

polycistronic RNA

69
Q

polycistronic RNA

A

one long mRNA that makes more than one protein
has a start and stop for each protein

70
Q

genes are normally off but can be turned on =

A

induced if a certain effector molecule is present

71
Q

inducible operons
example

A

usually code for genes involved in breakdown pathways (catabolic pathways)

lac operons codes for enzymes that break down lactose

72
Q

enzymes for lactose metabolism are produced if
Lactose (allolactose) is
lac operon will be on if

A

Lactose is present
effector
Lactose is present

73
Q

genes are normally on but can be tuned off=

A

repressed if a certain effector is present

74
Q

repressible operons
example

A

Are usually involved in synthesis pathways (anabolic pathways)
trp operon codes for enzymes that make the AA tryptophan

75
Q

enzymes for tryptophan are always made except when
effector
high amounts of tryptophan =

A

high levels of tryptophan are present
tryptophan
trp operon is off

76
Q

the lac operon codes for proteins involved in

A

lactose metabolism

77
Q

1 long mRNA is

A

operon

78
Q

lacZ
Chemical reaction

A

Codes for the enzyme b- galactosidase (breaks down lactose)

lactose-> galactose+glucose(main reaction)
lactose->allolactose

79
Q

lacY

A

codes for lactose permease (transports lactose into the cell)

80
Q

lacA

A

codes for enzyme lactose acetylase

81
Q

the lac promoter has __ regions
describe

A

3
promoter=lacP : region where the RNA polymerase binds
operator=lacO: where the lac repressor binds
cap site: where the cape activator binds

82
Q

LacI

A

codes for lac repressor
has its own promoter
not part of the lac operon

83
Q

The lac repressor is ____ produced=

A

always
consitutively expressed

84
Q

no lactose: lac operon=

A

off

85
Q

lac repressor protein is made in the ____ form

A

active

86
Q

lacI-> ___-> ____

A

mRNA
lac repressor protein

87
Q

when lac repressor binds to the operator it prevents the

A

RNA polymerase from binding to the lac promoter

88
Q

if RNA polymerase can’t bind to the lac promoter ___

A

no RNA or protein will be made form the lac operon

89
Q

lactose present: lac operon=

A

on

90
Q

repressor + allolactose ->

A

Inactive

91
Q

if lactose is present in the media, a small amount ___ the cell

A

enters

92
Q

lactose -> allolactose is by

A

B- galactosidase

93
Q

allolactose bins to lac ___ and converts it to the ___ form =

A

repressor
inactive
turn repressor off

94
Q

inactive form of repressor
effector

A

lac repressor+allolactose
allolactose

95
Q

the inactive form of the lac repressor ___ bind to DNA

A

can’t

96
Q

RNA polymerase binds to the ___ and makes ___

A

promoter
mRNA

97
Q

when RNA polymerase binds, the lac operon is

A

transcribed into a polycistronic mRNA

98
Q

mRNA is translated into __ proteins needed for

A

3
lactose metabolism

99
Q

the lac ___ is transcribed into a polycistronic mRNA which includes

A

operon
1 long mRNA
3 coding regions
start and stop codon for each coding region

100
Q

when lac operon is on, lac proteins are made at a ___ level

A

high

101
Q

permease is needed to

A

(transport protein) bring lactose into the cell are made

102
Q

many molecule of b-galactosidase enzymes are needed to

A

break down lactose

103
Q

when lactose is present :
the lactose repressor is in the ___ form
- bind
- formula
the lac operon ___ be transcribed into a polycistronic mRNA
if the lac operon is expressed, enzymes need to transport lactose into cell and break it down are produced at ___ level

A

inactive
repressor can’t bind to DNA
lac repressor + allolactose
may
high

104
Q

there are __ levels of regulation for the lax operon
the levels are

A

2
repressor and activator (cap)

105
Q

catabolism repression

preferred carbon source
expressed
present and form

A

glucose is the preferred carbon source (food)
genes for glucose metabolism are always expressed= constitutive expression
if glucose is present the genes for the metabolism of other alternate sugars (ex lactose) are turned off= repressed

106
Q

genes for the metabolism of other sugars rather than glucose will only be expressed if

A

glucose if absent and the alternate sugar (lactose) is present

107
Q

the lac operon is highly expressed when

A

lactose is present: the repressor can’t bind to the dna
glucose is absent : activator = cap binds to DNA

108
Q

cap activator greatly increases

A

amount of mRNA made

109
Q

cap activator proteins will bind to regions in the promoter of genes when

A

glucose is absent and turn them on

110
Q

the promoters of operons for alternate sugars are

A

usually weak

111
Q

RNA polymerase can’t recognize and bind to weak promoters without the help of a

A

activator protein

112
Q

contains many mismatches in conserved sequences in promoter

A

weak promoter

113
Q

cyclic AMP (cAMP)

A

controls whether CAP is in the active or inactive form

114
Q

high glucose -> ___ cAMP
low glucose-> ____ cAMP

A

low
high

115
Q

hi glucose ___ the enzyme that makes cAMP

A
116
Q

inactive form of CAP

A

cap by itself

117
Q

cal is in the inactive form when

A

high glucose is present in the cell

118
Q

active form of cap

A

cap + cAMP

119
Q

cap is in the active form when

A

low glucose is present in the cell

120
Q

CAP + cAMP will bind to promoter and help

A

RNA polymerase bind

121
Q

what is transcribed into mRNA

A

lac operon

122
Q

RNA polymerase can only bind if

A

cap activator binds to promoter region and lac repressor does not bind to operator

123
Q

lactose is present: lac repressor __ bind to operator
result

A

will not
lack operon may be transcribed into mRNA
nothing prevents the lac operon from being transcribed (it is no longer repressed)

124
Q

glucose is absent: Cap activator ___ bind to CAP binding site
result

A

will
CAP and cAMP bins to promoter, helps RNA polymerase bind, mRNA is made

125
Q

RNA polymerase can bind to promoter only if
cap
level
repressor
lactose

A

cap activator binds to cap site
low glucose/high cAMP
lac repressor does not bind to the operator
high lactose

126
Q

the lac operon is ___
the genes are normally turned ___ except when

A

inducible
off
lactose is present and glucose is absent

127
Q

low lactose, high glucose-> repressor ___ binds -> __ mRNA

A

Will
no

128
Q

high lactose, High glucose-> repressor ___ bind, RNA polymerase ___ bind-> __ mRNA

A

Does not
does not
no or low

129
Q

high lactose, low glucose-> cap ___ binds, RNA polymerase ___ binds, repressor ___ binds-> ___ mRNA

A

will
will
Does not
high levels of

130
Q

low lactose, low glucose-> cap and repressor ___ bind -> RNA polymerase __ bind -> __ mRNA

A

will
Can’t
no

131
Q

what do you need to express lac operon

A

hi lactose
low glucose

132
Q

glucose level controls

A

cap activity

133
Q

when tryptophan binds to the repressor in the trp operon

A

it will attach to the operator

134
Q

the repressor is normally ____ on the trp operon
lac operon

A

detached
attached