RR2 Flashcards
what is major regulator of gene expression
transcriptional control
describe percentages of gene expression
most outcomes of gene expression are dictated by Rates of transcription (73%)
MRNA translation (8%)
protein degradation (8%)
Mrna degradation (11%)
describe overview of transcription - why is polymerization energetically favoured by
high energy bond between alpha and beta phosphate is replaced
describe conventions for transcription rna transcript
dna pol read 3’ –> 5’
usptream = negative
transcription start site = +1
downstream = positive
utr = untranslated regions
what is premrna
not been processed yet
how fast does rna pol 2 advance
rate of 1000-3000 nt/min
not super fast but still fast
describe longest human gene
dmd = dystrophin
takes a day to transcribe once
for the rna pol to transcribe through it
must be very faithful = not make mistakes - cannot just fall off
name 3 stages of transcription
initiation
elongation
termination
describe initiation -3 stages of transcription
polymerase binds to the promoter sequence, locally denatures DNA & Catalyzes
the First phosphodiester linkage
promoter elements Recruit RNA pol, Catalyzes Reaction
+1 Site
describe elongation -3 stages of transcription
polymerase advances 3’–>5’ down template strand
denatures dna and polymerizes rna
generates molecules 5’ –> 3’
describe termination -3 stages of transcription
polymerase recognizes a stop site
releases completed rna
dissociates from dna
sequence gives signal to rna or dna pol to let go and fall of
are prokaryotic and eukaryotic transcription similar
yes but also distinct
Describe sigma factors
confer specificity to rna pol so correct gene transcribed
describe dna binding proteins
regulate rate of rna synthesis by enhancing or impeding rna pol binding to promoter regions
describe sequences in dna proximal to transcribed gene
Critical for efficient transcription
describe transcription for prokaryotes
Transcription is means of adapting - lots of allosteric effects
describe transcription for eukaryotes
essential during embryogenesis - distinguish all cell types - make complex organisms
30 trillion cells and 200 diff cell types
what does polycistronic mean
Prokaryotes
several products from one rna
what does monocistronic mean
eukaryotes
one rna –> one gene product
describe toxin alpha amanitin
mushroom toxin
use ion exchange chromatography
assay each fraction for ability to make rna
describe what toxin alpha amanitin will do to body
drug blocks some rna pols and destroys liver and blocks some rna polymerase
describe sensitivities of dna polymerases to toxin alpha amanitin
rna pol 1 = insensitive
rna pol 2 = very sensitive
rna pol 3 = intermediate sensitivity
describe rna pol 1
pre rrna (28s,18s, 5.5s)
involves in ribosome - components, synthesis
describe rna pol 2
mrna
snrna (small nuclear, produced in splicing)
sirna (small interfering)
mirnas (micro)
involved in encodes protein, rna splicing, chromatin mediated repression, transcriptional control
describe rna pol 3
trna
5s rna
snrna u6
7s rna
other small stable rnas
involved in protein synthesis, ribosome component, rna splicing, signal recognition, various functions, unknown for many
describe similarities between rna pols
They all exist in multimeric complexes
some show significant similarity to bacterial subunits
.most are essential
what is ctd
carboxyterminal domain on rna pol 2
series of repeats - needed to live
if get ride = compromise viability
describe ctd
close to where rna exits
Intrinsically disordered domains
describe clamp domain
when have few nts of rna made = clamp domain will close up tight around dna
= initiated elongation
want to be as possessive as possible
describe phopshorylation of ctd
during transcription, at or after transcription initiation
what colours correspond to actively transcribing and not transcribing genes and why
red = phosphorylated ctd = puffs where being transcribed
green = unphosphorylated ctd
what is phosphorylation of ctd of large subunit associated with
active transcription
morphologically distinct puffs
when does clamp domain enhance possessiveness of rna pol 2
enhances posessivity during elongation
