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Genetics > Gene Regulation > Flashcards

Gene Regulation Flashcards

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1
Q

what are cis regulatory elements

A

proteins that bind to DNA itself - enhancer sequence, basal promoter sequence, proximal control region

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2
Q

what are trans regulatory elements

A

proteins that bind to the cis regulatory elements - enhancers, transcription factors

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3
Q

what does the basal promoter sequence consist of

A

TATA box and CAAT box

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4
Q

what is promoter region responsible for

A

interaction of RNA pol II with its associated factors

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5
Q

whats the point of having both a basal and upstream promoters

A

allow for tight regulation

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6
Q

what do transcription factors do

A

help to grant specificity to RNA pol II regulated transcription

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7
Q

what promotes high levels of transcription?

A

enhancer, proximal promoters

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8
Q

level of expression with just the basal transcription machinery

A

low

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9
Q

where can enhancer be found

A

before gene, introns, or after gene

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10
Q

examples of eukaryotic transcription factors that must dimerize to function

A

leucine zipper, helix-turn-helix, zinc finger

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11
Q

what are DNA binding domain

A

part of transcription factors that only bind to certain DNA sequences

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12
Q

advantages of forming a dimer

A

adds an element of complexity and versatility

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13
Q

what does enhancer do to basal transcription apparatus

A

it stabilizes it thus increasing transcription levels

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14
Q

three modes of repressor action for transcription factors

A

quenching, blocking, competition

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15
Q

when does quenching occur with repressor proteins

A

repressor protein binds directly to the activator and hence can’t bind enhancer

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16
Q

when does competition occur with repressor protein

A

activator and repressor compete for binding to the enhancer

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17
Q

when does blocking occur with repressor protein

A

repressor binds to activation domain of the activator and now cant interact with basal transcriptional machinery

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18
Q

if repressor protein binds to the activation domain of the activator, can it still bind to the DNA

A

yeah but it is non functional

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19
Q

advantage of different genes having the same cis regulatory sequence

A

multiple genes can be regulated together - turned on and off at same time etc

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20
Q

short sequences of DNA within a gene promoter region that are able to bind a specific transcription factor and regulate transcription of genes

A

response elements

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21
Q

what allows the hypoxia inducible factors to bind and regulate transcription of genes

A

short DNA sequences (HREs) in the promoter of the genes

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22
Q

how do hypoxia element factors work

A

they (HIF alpha and HIF beta) must dimerize before they can bind to DNA sequences and regulate expression

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23
Q

what type of elements are the hypoxia inducible factors

A

cis regulatory elements

24
Q

most oxygen breathing species express what highly conserved transcriptional complex

A

HIF-1

25
Q

what does HIF do

A

allows for coordinated cellular response to low oxygen tension

26
Q

name giving to normal cells with oxygen stress

A

normoxia

27
Q

fate of HIF-1 alpha under normal oxygen conditions

A

they are degraded by proteasomes in the cytoplasm and genes for hypoxia response are not expressed

28
Q

fate of HIF-1 alpha under low oxygen state

A

HIF-1 alpha is not degraded and it enters cell nucleus where it forms dimer with HIF-1 beta allowing it to bind to DNA of target genes carrying hypoxia response element (HRE)

29
Q

Induction of expression of a family of genes by transcription factor binding to a common enhancer sequence of many different genes is an example of?

A

cells in hypoxia state

30
Q

what happens inside a tumor that causes it to grow

A

so there is no oxygen inside a tumor hence HIF-1 alpha is not degraded. HIF-1 alpha stimulates angiogenesis (development of new blood vessels) hence giving supply for tumor to grow

31
Q

reason why we learn about hypoxia in relation to how we should treat tumor

A

if we could find a way to inhibit HIF-1 alpha and beta inside tumors we can stop its growth

32
Q

glucocorticoid receptors is what type of transcription factor

A

zinc finger TF

33
Q

What does activated glucocorticoids receptor do in nucleus and cytosol

A

upregulates expression of anti inflammatory genes in nucleus

represses expression of pro inflammatory proteins in cytosol

34
Q

glucocorticoids is used as treatment for

A

glucocorticoid deficiency and to suppress the immune system

35
Q

key thing to note about glucocorticoid response elements DNA sequence

A

they are inverted repeats

36
Q

what happens to glucocorticoid receptors in cytoplasm in absence of glucocorticoids

A

become part of an inactive multi-protein complex

37
Q

when happens when cortisol (glucocorticoids) is present in cytoplasm

A

its receptors dissociate from the multi protein complex, dimerizes, and moves to the nucleus

38
Q

what do glucocorticoids receptors do in nucleus

A

induce or repress target genes

also bind response element DNA in the promoter regions of glucocorticoid-responsive genes

39
Q

what is the myc/max system

A

regulatory mechanism that switches between gene activation and repression

40
Q

in absence of myc, what does max do

A

max dimers with itself (homodimer) and represses gene transcription

41
Q

what does myc do with its transcriptional regulation domain

A

it has to dimer with max first before it can bind to DNA then regulates expression of genes involved in cell cycle progression

42
Q

when is max expressed and myc not

A

in non proliferating cells

43
Q

in presence of myc what happens

A

myc and max dimerize (heterodimer) and activate gene expression

44
Q

difference between myc/max heterodimer and max homodimer

A

myc/max - gene expression (more favorable)

max/max - gene suppression

45
Q

problem with myc over expression in tumors/cancers

A

it will favor forming the heterodimer with max and will promote cell proliferation

46
Q

Processes long primary- miRNAs to pre-miRNA hairpin structures

A

Drosha

47
Q

Base pairing between miRNA and target mRNA give what

A

target specificity

48
Q

what happens if specificity is not complete with miRNA

A

one miRNA can silence many mRNA

49
Q

what further processes pre-miRNA to single stranded RNA and initiates the formation of the RNA-induced silencing complex (RISC)

A

dicer

50
Q

is it common in human for mRNA to be regulated by miRNA

A

yeah

51
Q

how does miRNA regulate gene expression in mRNA

A

it binds to the 3’ UTR and base pairs to it preventing interaction of translational machinery with the 5’ cap structure

basically prevents mRNA from getting translated

52
Q

miRNA are normally involved in what type of regulation

A

cell proliferation

53
Q

what happens to the genes that code for miRNA in tumor cells

A

amplified so they proliferate uncontrollably

54
Q

short interfering RNA (siRNA) is processed by what type of enzyme

A

dicer

55
Q

Double stranded RNA Often transcribed of two opposable promoters in a gene delivery vector

A

siRNA

Genetics (19 decks)

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