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e x a m IV Flashcards

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1
Q

negative control

A

gene transcription is actively repressed

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2
Q

with repressor:

A

no transcription

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3
Q

without repressor:

A

transcrption

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4
Q

positive control

A

gene transcription is induced

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5
Q

with activator protein

A

transcription

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6
Q

without activator protein

A

no transcription

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7
Q

effector molecule

A

regulates the function of activators and repressors

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8
Q

with effector bound to repressor:

A

transcription

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9
Q

without effector bound to repressor:

A

no transcription

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10
Q

what does effector to do to repressor protein

A

changes confirmation

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11
Q

with effector bound to activator:

A

translation

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12
Q

without effector bound to activator:

A

no translation

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13
Q

allosteric effector

A

binds to the allosteric site of regulatory protein leading to conformational change

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14
Q

effector present in activator site

A

protein binds to binding (allosteric site)

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15
Q

effector present in repressor site

A

effector causes protein to be removed from active binding site

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16
Q

permease

A

transports lactose into cell

permeate

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17
Q

beta-galactosidase

A

cleaves lactose to produce galactose & glucose

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18
Q

the lac system is used in…

A

prokaryotes

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19
Q

what induces the synthesis of beta-galactosidase and permease?

A

addition of certain sugars

  • glucose
  • lactose
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20
Q

how many promotors are there for multiple genes in prokaryotes?

A

ONE

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21
Q

I gene codes for

A

repressor protein

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22
Q

repressor protein controls…

A

responsiveness to lactose

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23
Q

what does lactose do?

A

binds to repressor protein
removes repressor from DNA
lac Z and lac Y gene are expressed

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24
Q

I- mutant

A

defective repressor protein
causes operon to be ON all the time
continuous mRNA transcription

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25
Is (supressor) mutant
suppression of gene expression lactose can no longer bind to repressor galactosidase or permease are NEVER expressed
26
Operator
specific region downstream from promotor | DNA sequence that the repressor binds to
27
Oc mutant
causes repressor protein to not be able to bind to operator | b-galactosidase & permease are ALWAYS ON
28
lac promoter
physically blocks RNA polymerase from working | stop sign in front of operator
29
two consensus sequences for efficient RNA polymerase binding in prokaryotes
``` -35 region pribnow box (-10 base pairs) ```
30
lac operon is shut down when...
lactose is not present
31
POZY
promoter operon lac z gene lac y gene
32
glucose blocks the induction of lactose metabolism...
because glucose is more energetically favorable | glucose is processed first over lactose
33
adenylate cyclase produces
cAMP
34
what does cAMP bind to
CAP | catabolic activator protein
35
what does cAMP-CAP do?
binds promotor and facilitates RNA polymerase bind and transcription initiation STABILIZES the protein
36
what does glucose do to the lac system?
glucose metabolite block activity of adenylate cyclase ATP--> cAMP conversion is shut down cAMP-CAP complex is not formed no expression of lac operon
37
cis regulatory element
in the same segment of DNA as the gene of interest
38
trans regulatory element
factors produced by other genes that act on the gene of interest not located in the same spot of the bacterial chromosome
39
trp operon
controlled by 5 biosynthetic genes | encoded for within a single operon
40
how is trp operon regulated
tryptophan levels
41
primary control of trp protein
trp repressor binds tryptophan and turn off the operon when tryptophan levels are adequate binds to operator to block RNA polymerase movement aka: on/off switch due to adequate levels of tryptophan
42
secondary control of trp protein
stem & loop folding to ensure used to either terminate | loop forms when in excess of tryptophan
43
when high tryptophan
stem & loop form | termination of transcription
44
when low tryptophan
ribosome is stalled at trp codons | transcription continues
45
why gene reg is more complicated in eukaryotes than prokaryotes:
each gene is separately controlled by a single promoter numerous proteins contribute to gene reg multiple DNA switches ground state is OFF
46
what is required for binding RNA polymerase to eukaryotic promoters?
GC-rich box CAAT box TATA box
47
changing promotor sequences will lead to...
dramatic reduction of transcription
48
general transcription factors
recruit RNA polymerase II to TATA box
49
specific transcription factors
directly bind to DNA to influence transcription of target genes help or hinder pre-initiation complex stabilize RNA polymerase binding
50
why is DNA looped?
it is exposed to more activators, enhancer sites, repressors | all helps with stability
51
what is DNA binding domain needed for?
specific transcription factors to bind to enhancer/silencer DNA sequence
52
activation domain
needed to interact with proteins bound to promoter to speed up / slow down transcription
53
GAL-4
yeast transcription factor for lactose metabolism
54
what regulatory gene is lac-z linked to?
GAL-4
55
synergism
interaction between two factors; combined effect is greater than the SUM of the two
56
nitric oxide synthetase
makes NO in cells
57
what happens when interferon gamma & LPS act alone
little or no increase in NOS
58
what happens when interferon gamma & LPS work together?
LARGE increases in NOS mRNA
59
heterochromatin
darkly stained regions of the chromosome | some gene expression
60
euchromatin
lightly stained regions | main site of gene expression
61
nucleosome
8 separate proteins multiple coiled on top of each other fit inside nucleus
62
histones
group of proteins that packages DNA into chromatin
63
function of chromatin remodeling
displace nucleosomes to allow transcription factors to bind to DNA regulatory regions
64
SWI-SNF protein
moves nucleosomes out of the way
65
histone acetyltransferase (HAT)
adds acetyl group to histone tails
66
histone deacetyltransferase (HDAT)
removes acetyl groups from histones | --> decreased transcription
67
beta-inferon
encodes antiviral protein inferno | is activated at high levels with viral infection
68
enhanceosome
moves nucleosomes out of the way for access to TATA box
69
GCN5
coactivator protein that acetylates nucleosome
70
CBP protein
coactivator with histone acetylase activity | recruits RNA polymerase II
71
epigenetics
study of inherited changes in gene expression without a change in the underlying DNA sequence
72
epigenetics is...
the inheritance of HOW the gene is expressed not WHAT genes are expressed
73
silencing is generated in DNA methylation without...
any change in the DNA sequence
74
what happens to one of the X chromosomes in females?
inactivated through methylation so double the genes aren't expressed

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