Biochem Abnormal Amnio RNA syn
Terms
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- describe the components of a transcription unit
- promoter, through terminator
- genes transcribed left to right use which strand as template
- use the bottom strand as template
- genes transcribed right to left use which strand as template
- use top strand
- -35, -10
-
-35: where RNA pol initially interacts
-10 pribnow - how many RNA pols do prok have?
- one
- describe RNA pol in transcription
-
holoenzy with six subunits
sigma - binds promoter, stabalizes/enhances affinity for binding
beta - active site/catalytic binds nucleoside triphosphates
beta' - binds DNA template
omega - renatures polymerase after its been dissociated
alpha - assembly and regulation
syn first 9nt's then initiation ends and sigma released - Rho indep termination of transcription, whats in the stem?
-
GC
RNA pol is released - RHO dependent
-
atpase six subunits
binds C rich recog site in RNA chain
5'3' helicase catches up with RNA pol when it pauses
REQ ATP -
PROK rRNA
precursor?
30S?
50S? -
30S precursor
16S 23S 5S
30S - 16S
50S - 23S 5S -
Euk rRNA
precursor
40S
60S -
TRanscribed and nontranscribed spacers
40 - 18S,
60 - 5.8 28 5TRNA(pol III) - RNA pol II
-
more than 10 subunits
two largest are catalytic activity
C-terminal domain (phos'd by TFIIH to proceed from initiation to elongation)
binds dna non spec -
RNA pol I in euk
General transcription factors -
UBF1 - binds core promoters
SL1 -binds ubf1
RNApol I is then recruited - initiator is purine or pyrimidine rich?
-
pyrimidine
conserved sequence around start of transcription - What else is in the promoter besides the core promoter
- URE - upstream regulatory elements, bind specific transcriptional activators
- TRanscriptional activators have what two domains
-
DNA binding - zn finger hlh homeo domains, leu zipper
transcription activation - glu rich, facilitates interaction with other factors - activation domain of transcriptional activator does what
- initiation and elongation rate
- What is important about TAF's?
- one of them has a HAT activity
- what are HDACs
- histone deacetylases remove actyl groups from histon tails
-
EUK pre-initiation complex
PIC -
TBP binds minor groove - only member to make direct contact
TFIID = TBP + TAF's
TFIIA/B join stabilizing its binding
TFIIF (atp dep helicase)brings in RNA pol II
TFIIE joins - Initiation of transcription in euk
-
first phosphodiester bond forms using ATP hydrolysis
TFIIH (helicase) and TFIIJ join
TFIIH phosphorylates C terminal domain of RNA pol II - how do you move from preinitiation complex to initiation?
-
TFIIH phosphorylates C terminal domain of RNA pol II
release GTF's, after 60-80 nt's rest of TFII's are released - Wilms disease
-
WT-1 is a tumor suppressor
repressor activity of WT-1 inactivated when it's mutated in WILMS TUMOR - Post transcriptional (have made the mRNA) processing in euk tRNA
- tRNA addition of CCA, 3' end trimmed, 5' end trimmed, intron in anticodon stem removed, base modifications
- POST Transcriptional(have made the mRNA) processing in EUK
- tRNA, mRNA cap/tail(ATP, not req for getting out of nucleus), splicing,
-
Four groups of introns and how you remove them
I
II*
III*
IV -
I and II - ribozyme autocat, lower euk
II and III- lariat, autocat(self splicing)
III spliceosome
IV endonuclease and ligase (yeast) - Spliceosome
-
snRNA's and snRNP's (U1-6 lots of uracil)
REQ ATPfor assembly - name the three splice sites
-
donor GU 5'
acceptor AG 3'
A branch site - How does the spliceosome work
-
U1 binds donor
U2 binds branch
U4-6 bind and spliceosome is complete
Activated A cleaves exon-intron
2'5'linkage
acceptor cleaved - beta thalassemia
- improper splicing