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cell proliferation > transcription and splicing > Flashcards

transcription and splicing Flashcards

(55 cards)

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1
Q

how many base pairs of DNA sequence does the human genome contain

A

3 billion

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2
Q

how must the expression of genes be regulated

A

both spatially and temporally

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3
Q

how many classes of RNA polymerase do eukaryotic cells contain

A

3

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4
Q

what are the 3 types of RNA polymerase

A

RNA polymerase I-III

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5
Q

what does RNA polymerase I do

A

transcribes ribsomal RNA in the nucleus - components of ribosomes (rRNA)

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6
Q

what does RNA polymerase II do

A

transcribes messenger RNA (mRNA: protein coding) in the nuceloplasm

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7
Q

what does RNA polymerase III do

A

transcribes 5S rRNA, tRNA and other small RNAs in the nuceloplasm (translation of mRNA into protein)

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8
Q

how frequent are histones on a DNA strand

A

every 110 base pairs

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9
Q

how many subunits do eukaryotic RNA polymerases contain

A

~12

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10
Q

what does the largest subunit in RNA polymerase II have

A

a carboxy-terminal domain (CTD) consisting of multiple repeats of a heptamer

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11
Q

what do promoter regions do

A

recruit RNA polymerase and opens DNA

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12
Q

what does 5’ UTR signal for

A

initiation of translation

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13
Q

what is transcription

A

the copying of a DNA strand onto an RNA strand

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14
Q

what does 3’ UTR contain

A

translational termination signals

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15
Q

what are the 4 stages of transcription

A

template recognition, initiation, elongation and termination

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16
Q

what occurs during template recognition

A

RNA polymerase binds to duplex DNA, and DNA is unwound at the promoter

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17
Q

what happens during initiation

A

chains of 2-9 bases are synthesized and released

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18
Q

what happens during elongation

A

RNA polymerase synthesizes RNA, unwound region moves with RNA polymerase, RNA polymerase reaches the end of the gene

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19
Q

what happens during termination

A

RNA polymerase and RNA are released

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20
Q

what must happen before RNA polymerase can bind to the promoter

A

chromatin must be opened

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21
Q

what are basal transcription factors

A

transcription factors required by RNA polymerase II to form the initiation complex at all RNA polymerase II promoters - factors are identified as TFIIX (X=letter)

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22
Q

what are coactivators

A

factors required for transcription that do not bind DNA, but are required for DNA-binding activators to interact with the basal TFs

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23
Q

what is a TATA box and what does it consist of

Study These Flashcards
A

a common component of RNA polymerase II promoters which consist of an A-T-rich octamer located ~25bp upstream of the startpoint

24
Q

what is the TATA-binding protein (TBP)

Study These Flashcards
A

a component of the positioning factor that is required for each type of RNA polymerase to bind its promoter

25
what is the basal TF for RNA polymerase II
TFIID
26
what is initiation followed by
promoter clearance and elongation
27
which basal TFs are required to melt DNA to allow polymerase movement
TFIIE and TFIIH
28
what is required for promoter clearance and elongation to begin
phosphorylation of the C-terminal domain (CTD) or RNA polymerase II
29
what are enhancer regions
sequences which transcription factors bind to
30
where are enhancer regions located
can be upstream OR downstream from the promoter
31
what do enhancers form complexes of
activators that interact with the promoter
32
what are reppressors
a protein that inhibits expression of a gene, may act to prevent transcription by binding to an enhancer or silencer
33
what do enhancers typically activate
the promoter nearest to itself
34
what are mediator complexes
controls transcription by recruiting either protein-coding RNA or non-coding RNA genes to promote or repress transcription initiation - they adapt easily
35
how do enhancers work
by increasing the concentration of activators near the promoter
36
what is p53a
a TF
37
what does a cap at the 5' end of mRNA enable
reading by a ribosome
38
what happens during splicing
pre-mRNA exon-intron junctions are broken, and exons are joined to create mature mRNA
39
how are 5' methylated caps formed
by adding a G to the terminal base of the transcript via a 5'-5' link
40
where does the capping process take place
during transcription
41
what are the splice site consensus sequences
5' splice site = GU 3' splice site = AG
42
how are splice junctions read
in pairs
43
how many stages does splicing occur in
2
44
what are the stages in splicing
- first the 5' exon is cleaved off - the intron is then released as a lariat when it is cleaved at the 3' splice site, and the left and right exons are then ligated together
45
when can splicing occur
during or after transcription
46
what is splicing connected to
the mRNA export and stability control
47
what is alternative splicing
exons from the same gene are joined in different combinations, leading to different mRNA transcripts
48
what are the different modes of alternative splicing
- intron retention - alternative 5' splice sites - alternative 3' splice sites - exon inclusion/skipping - mutually exclusive exons - combinatorial exon selection - alternative promoter/splicing - alternative polyadenylation/splicing
49
what are the 3' ends of mRNAs generated by
cleavage and polyadenylation
50
what is the sequence AAUAAA a signal for
cleavage to generate a 3' end of mRNA that is polyadenylated
51
what do poly(A)polymerases do
add ~200 A residues to the 3' end of the RNA
52
where do the specificity factor and endonuclease cleave RNA
downstream of AAUAAA
53
what does the poly(A) tail control
mRNA stability and influences translation
54
what are siRNAs
~21-22 nucleotides long incorporated into RNA-induced silencing complex (RISC) involved in gene regulation, transposon control and viral defence
55
what are miRNAs
~19-22 nucleotides long incorportated with argonaute proteins into RNA-induced silencing complex involved in post-transriptional gene regulation

cell proliferation (12 decks)

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