Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Genetics 380 > Gene Regulation In Prokaryotes > Flashcards

Gene Regulation In Prokaryotes Flashcards

1
Q

constitutive genes

A

“on” all the time aka housekeeping genes; their proteins perform functions that are necessary for basic function, vitality, and maintenance of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

regulated genes

A

aka inducible/repressible genes; increased/decreased as cell’s needs change (ex: lac operon and trp operon)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Pribnow box

A

specific regulatory sequence in a promoter region; #s indicate position relative to transcription start sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

sigma factor

A

allows RNA polymerase to bind to DNA; several different types; each one interacts w different promoters & turns of different genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

cis-operating factors

A

affect activity on same DNA molecule in which they reside (ex: promoter sequences bind sigma factor more efficiently than others aka strong promoters which produces higher rate of transcription)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

every copy of a gene has…

A

…its own promoter region as well as coding sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

trans-operating factors

A

molecules that bind to regulatory sequences; made by genes on main chromosome and diffuse over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

activator proteins

A

trans-operating; bind to sigma factor & inc. transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

repressor proteins

A

trans-operating; decrease binding of sigma factor and decrease transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

operon

A

enable organism to activate or inhibit expression of several proteins in response to one regulatory molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

inducible operons

A

usually off; get turned on when cell needs their proteins (ex: operons that encode enzymes that catabolize nutrient molecules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

repressible operons

A

usually on; get turned off when their proteins are no longer needed (ex: operons that encode enzymes that synthesize amino acids or other important molecules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

operon contains:

A

structural genes; promoter; operator; regulator gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

structural gene in operon

A

encodes the proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

promoter in operon

A

site where molecules that control activity in operon bind; must be bound by RNA polymerase for transcription to occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

operator in operon

A

site to which molecules that control activity in operon bind; where the repressor can bind to prevent transcription or activator can bind to promote transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

regulator gene in operon

A

not contiguous w operon - it lies at a variable distance from operon; makes a protein that regulates whether operon is on or off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

negative control

A

regulator protein is a repressor; when repressor bind to operator of operon, it prevents RNA polymerase from binding to operon’s promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

positive control

A

regulator protein is activator; RNA polymerase bind promoter weakly; binding of the activator protein to activator binding site enables RNA polymerase to bind to the promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

negative inducible operon

A

regulatory gene makes repressor protein which is made in active form; inducer induces transcription by inactivating repressor and preventing it from binding to operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

positive inducible operon

A

regulatory gene makes activator protein which is made in inactive form; inducer induces transcription by activating activator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

negative repressible operon

A

regulatory gene makes repressor protein which is made in inactive form; corepressor represses transcription by activating repressor and enabling it to bind to operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

positive repressible operon

A

regulatory gene makes activator protein which is made in active form; repressor represses transcription by inactivating activator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

lac operon

A

negative and positive control; contains structural genes lacZ, lacY, and lacA; inducible: not needed unless lactose is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
lacZ
encodes beta-galactosidase which breaks lactose into glucose and galactose
26
lacY
encodes permease which transport lactose into the cell
27
lacA
encodes transacetylase (function unknown)
28
lacI
controller of inducibility encodes lac repressor which bind the operator and prevents transcription; lies at a distance from operon so repressor is trans-acting factor
29
allolactose
lactose is converted to allolactose which bind to repressor and prevent it from binding to operator; transcription occurs proteins are made lactose gets catabolized; when level of lactose drops repressor represses transcription again
30
Jacob and Monod
discovered mechanism for gene regulation in lac operon using E. coli strains that had mutations in different portions of lac operon
31
E. Coli experiment
using partial diploids w plasmid w own copy of lac operon ; during conjugation donor bacterium gives recipient plasmid copy of lac operon
32
lacY and lacZ
work independently; Jacob and Monod
33
lacZ+ lacY- or lacZ- lacY+
these genotypes could make both beta-galactosidase and permease; Jacob and Monod
34
mutation in one copy of beta-galactosidase or permease
does not affect protein production from other copy of that gene (cis acting factor); cell had one working copy of each gene and could metabolize lactose; Jacob and Monod
35
Z, Y and A genes
not completely independent of each other; translation of Z is stopped in mRNA Y and A mRNAs will not get translated; nonsense mutation in one of operon's genes can cause no translation of any of the downstream genes
36
mutation in lacI (Jacob and Monod)
caused repressor protein to be inactive so transcription was always on (lacI- genotype)
37
lacI+ lacZ-/lacI- lac Z+
does not produce beta-galactosidase in absence of lactose which means repressor protein from main chromosome's I gene could diffuse to bind other copy o f operon in plasmid (repressor is trans-acting factor); doesn't produce BG only when lactose is present bc functional repressor molecules that are made by main chromosome's I gene must be inactivated by allolactose in order for there to be transcription
38
superrespressor mutations
prevents inducer (allolactose) from binding to repressor leaving repressor always active and inducer unable to induce transcription (genotype = lacIs); trans acting factor will repress both copies of operon even in presence of lactose
39
lacIs lacZ+/lacI+ lacZ+ or lacIs lacZ+/ lacI- lacZ+
does not produce beta-galactosidase even when lactose is present
40
lacOc genotype
discovered by Jacob and Monod; prevented repressor from binding - transcription was always on
41
lacOc lacZ+/lacO+ lacZ+
produces beta-galactosidase all the time even when lactose is absent because the repressor cannot bind the operator
42
lacI+ lacO+ lacZ-/lac+ lacOc lacZ-
produces beta-galactosidase all the time even when lactose is absent bc plasmid's Oc mutation drives transcription of plasmid's Z+ gene
43
lacI+ lacO+ lacZ+/lacI+ lacOc lacZ-
produces beta-galactosidase only when lactose is present bc plasmid Z- gene will not make function beta-galactosidase under any conditions this nullifies the Oc mutation's effect on beta-galactosidase production
44
cis-acting element
lacP- genotype; promoter mutations that prevent the RNA polymerase from binding to the promoter
45
lacI+ lacP+ lacZ+/lacI+ lacP- lacZ+
produces beta-galactosidase normally when lactose is present (from the main chromosome); promoter mutation in the plasmid doesn't prevent transcription in the main chromosome - promotor is a cis acting element
46
positive control
when glucose is present the bacterium will prefer to use it for energy vs. lactose and will shut down the lac operon
47
activator binding site
little way upstream from lac operon
48
glucose present
cAMP is low there is little CRP -cAMP complex to bind to activator binding site and transcription stops
49
glucose drops
cAMP rises allowing CRP and cAMP to bind resulting in activation of the lac operon
50
trp operon
contains 5 structural genes that work together to synthesize the amino acid tryptophan; needed for cell to be active except in presence of ample tryptophan; regulatory gene makes repressor protein which is made in inactive form; negative repressible operon
51
tryptophan
corepressor of trp operon; when present it binds the repressor and allows repressor to bind operator transcription stops until the level of tryptophan decreases; concentration of tryptophan determines if ribosome can smoothly translate leader mRNA which determines if structural genes of trp operon get transcribed
52
regulon
group of operons that are controlled by activators and repressors that diffuse throughout nucleoid
53
2nd means of negative control of trp
can be attenuated
54
leader gene (trpL)
trp operon; lies between operator and five structural genes whose proteins synthesize tryptophan; RNA polymerase transcribes leader mRNA + ribosomes translate leader mRNA creating leader peptide
55
region 1 in trp operon
in leader sequence - contains 2 consecutive tryptophan codons
56
regions 2, 3, and 4 in trp operon
region 3 can form stem loop structure by binding w region 2 or region 4 but not both (prefers to bind to region 2)
57
region 4
RNA polymerase binds just after region 4 to transcribe structural genes
58
regions 3 and 4
bind together stem loop blocks RNA polymerase binding site
59
regions 2 and 3
bind region 4 is open and RNA polymerase can bind and transcribe the structural genes
60
high tryptophan levels
ribosome has no trouble reading through two tryptophan codons bc there is plenty of tryp
61
low tryptophan
ribosome stalls as it tries to translate the leader peptide bc it has trouble finding the tryptophan-tRNAs it needs; this allows step loop to form between regions 2 ad 3 which allows RNA polymerase to bind around region 4 and transcribe the structural genes of the trp operon
62
archaeal transcription factors
can activate and repress transcription (ex: pyrococcus furiosus)
63
TrmBL1 protein
represses genes that make transport proteins for other sugar and activates genes for gluconeogenesis (synthesis of glucose)
64
TrmBL1
binds downstream of B recognition element and TATA box of the genes that encode maltodextrin and maltose/trehalose and prevents RNA polymerase from transcribing them; also binds to site upstream of B recognition element and TATA box of genes that encodes enzymes that synthesize glucose and recruits TBP, TFB, and RNA polymerase to the site activating transcription
65
TrmBL1 uses
one binding site to repress transcription and a different binding site to induce transcription
66
signal transduction pathways (2 component regulatory systems) activate transcription factors
(1) molecules from environment bind to extracellular domain of transmembrane protein that sensor kinase - when signal molecule binds sensor kinase phosphorylates itself (autophosphorylation) (2) phosphate group is transferred to response regulator which is a transcription factor that is activate by phosphorylation (3) response regulator then activates/inhibits its target genes
67
microbes activate genes via quorum sensing
glowing bacteria; secrete activator AHL which can activate several genes to make fluorescent protein called luciferase; when only a few bacteria AHL diffuses into environment and doesn't enter bacterial cells; once enough bacteria AHL concentration in envir. gets high enough for AHL to diffuse into bacterial cells and AHL turns on the genes that make luciferase bacteria glow
68
quorum sensing
uses diffusible transcription activators
69
virulence factors are activated via quorum sensing
staphylococcus aureus causes serious wound infections + pneumonia - quorum sensing enables them to secrete their toxins; make inducer AIP transport out of cell w enough bacteria AIP binds to sensor kinase ArgC causing it to autophosphorylate; phosphate transferred to transcription activator ArgA which induces activity in genes that encode virulence proteins that help bacterium adhere to/invade your cells and secrete toxins
70
stringent response in bacteria
low concentration of nutrients in environment; synthesis of rRNA and tRNA and ribosomes stops; amino acid synthesize increase which enables synthesis of new proteins to compensate for lack of certain nutrients in environment (ex: enzymes to synthesize amino acids that are now no longer available)
71
translation regulated by antisense RNAs
have sequences complementary to certain genes' mRNAs can bind to these mRNAs and increase/decrease translation depending on which mRNA
72
enabling translation by altering 2ndary structure of mRNA
RpoS mRNA has 2ndary structure near 5' end that gets cleaved by RNAse making impossible for ribosome to translate mRNA; DsrA siRNA binds to 5' end of RpoS mRNA changing mRNA's 2ndary structure and changing cut site for RNAse enabling translation
73
translation regulation by antisense RNAs
ex: decreasing translation - ompF gene encodes channel that allows water and ion to pass into cell when environment has high osmolarity micF gene (encodes mRNA interfering complementary RNA: iRNA) is activated micF RNA binds to 5' region of ompF mRNA inhibiting ribosome binding and translation which prevents cells from accumulating too high ion concentration
74
riboswitches
region where proteins and other molecules can bind and control if translation takes place or not; product inhibition - end product of synthetic pathway is regulatory molecules when it binds this inhibits ribosome binding to mRNA and inhibits protein production
75
ribozymes and end product inhibition
regulates translation; RNAs contain region where molecules can bind and cause mRNA to cleave itself (ribozymes); RNAs make genes that synth. various molecules when too high concentration of product molecule it binds to ribozyme and causes mRNA to cleave itself

Genetics 380 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions