RR2

Question 1

what is major regulator of gene expression

Answer 1

transcriptional control

Question 2

describe percentages of gene expression

Answer 2

most outcomes of gene expression are dictated by Rates of transcription (73%)
MRNA translation (8%)
protein degradation (8%)
Mrna degradation (11%)

Question 3

describe overview of transcription - why is polymerization energetically favoured by

Answer 3

high energy bond between alpha and beta phosphate is replaced

Question 4

describe conventions for transcription rna transcript

Answer 4

dna pol read 3’ –> 5’
usptream = negative
transcription start site = +1
downstream = positive
utr = untranslated regions

Question 5

what is premrna

Answer 5

not been processed yet

Question 6

how fast does rna pol 2 advance

Answer 6

rate of 1000-3000 nt/min
not super fast but still fast

Question 7

describe longest human gene

Answer 7

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

Question 8

name 3 stages of transcription

Answer 8

initiation
elongation
termination

Question 9

describe initiation -3 stages of transcription

Answer 9

polymerase binds to the promoter sequence, locally denatures DNA & Catalyzes
the First phosphodiester linkage
promoter elements Recruit RNA pol, Catalyzes Reaction
+1 Site

Question 10

describe elongation -3 stages of transcription

Answer 10

polymerase advances 3’–>5’ down template strand
denatures dna and polymerizes rna
generates molecules 5’ –> 3’

Question 11

describe termination -3 stages of transcription

Answer 11

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

Question 12

are prokaryotic and eukaryotic transcription similar

Answer 12

yes but also distinct

Question 13

Describe sigma factors

Answer 13

confer specificity to rna pol so correct gene transcribed

Question 14

describe dna binding proteins

Answer 14

regulate rate of rna synthesis by enhancing or impeding rna pol binding to promoter regions

Question 15

describe sequences in dna proximal to transcribed gene

Answer 15

Critical for efficient transcription

Question 16

describe transcription for prokaryotes

Answer 16

Transcription is means of adapting - lots of allosteric effects

Question 17

describe transcription for eukaryotes

Answer 17

essential during embryogenesis - distinguish all cell types - make complex organisms
30 trillion cells and 200 diff cell types

Question 18

what does polycistronic mean

Answer 18

Prokaryotes
several products from one rna

Question 19

what does monocistronic mean

Answer 19

eukaryotes
one rna –> one gene product

Question 20

describe toxin alpha amanitin

Answer 20

mushroom toxin
use ion exchange chromatography
assay each fraction for ability to make rna

Question 21

describe what toxin alpha amanitin will do to body

Answer 21

drug blocks some rna pols and destroys liver and blocks some rna polymerase

Question 22

describe sensitivities of dna polymerases to toxin alpha amanitin

Answer 22

rna pol 1 = insensitive
rna pol 2 = very sensitive
rna pol 3 = intermediate sensitivity

Question 23

describe rna pol 1

Answer 23

pre rrna (28s,18s, 5.5s)
involves in ribosome - components, synthesis

Question 24

describe rna pol 2

Answer 24

mrna
snrna (small nuclear, produced in splicing)
sirna (small interfering)
mirnas (micro)
involved in encodes protein, rna splicing, chromatin mediated repression, transcriptional control

Question 25

describe rna pol 3

Answer 25

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

Question 26

describe similarities between rna pols

Answer 26

They all exist in multimeric complexes
some show significant similarity to bacterial subunits
.most are essential

Question 27

what is ctd

Answer 27

carboxyterminal domain on rna pol 2
series of repeats - needed to live
if get ride = compromise viability

Question 28

describe ctd

Answer 28

close to where rna exits
Intrinsically disordered domains

Question 29

describe clamp domain

Answer 29

when have few nts of rna made = clamp domain will close up tight around dna
= initiated elongation
want to be as possessive as possible

Question 30

describe phopshorylation of ctd

Answer 30

during transcription, at or after transcription initiation

Question 31

what colours correspond to actively transcribing and not transcribing genes and why

Answer 31

red = phosphorylated ctd = puffs where being transcribed
green = unphosphorylated ctd

Question 32

what is phosphorylation of ctd of large subunit associated with

Answer 32

active transcription
morphologically distinct puffs

Question 33

when does clamp domain enhance possessiveness of rna pol 2

Answer 33

enhances posessivity during elongation