BIO 351 Lecture Notes - Lecture 11: Rna Polymerase Ii, Consensus Sequence, Speed Bump
Transcription, RNA Processing, and Translation Objectives
1. Be ale to da DNA ad RNA uleotides ad distiguish the fo eah othe ou do’t eed to da the
seuees of the itoge ases… just the deoiose ad the phosphate
RNA DNA
2. Not all ateial pootes hae the eat sae DNA uleotides ithi the osesus seuee at -10 and -35.
Explain the significance of these sequence differences.
− Need consensus to have a generally agreed upon, widely recognized promoter sequence
− If there were all the same sequences then they would all have the exact same level of expression
− B hagig the seuees, ou affet the affiit of the “iga Fato o TF II D i eukaotes ad that’s
going to allow for different levels of expression
− Expression level is coded by -35 to -10 (in prokaryotes)
3. Explain the role of RNA secondary structure in termination of transcription (hairpin)
− Termination sequences include inverted repeats
o CpG rich region of mRNA will bend back on itself and make base pairs
o This secondary structure, called a hairpin, acts like a speed bump and makes the RNA Polymerase slow
down to a halt (through a poorly understood mechanism)
o With RNA Polymerase already halted, it just needs to dissociate from the DNA strand
o These base pairs are broken either in a Rho independent or Rho dependent method
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4. Initiation of transcription in eukaryotes is more complex than in prokaryotes, involving many proteins and DNA
sequences. Why do multicellular organisms require more complex regulation of gene expression?
− Default epessio i pokaotes is o
− Default epessio i eukaotes is off and must go to great lengths to turn them on
o This is likely because eukaryotes are more complicated, have different cell types, have different cell
regions, and need a lot more coordination
o Having all of them off by default, allows the cell to them go through and turn on the ones that only need
to be turned on (or increased) for specific cells in specific regions
o In patiula, the uleus is seletie o hat it allos to tael i ad out, heeas pokaotes do’t
have a nucleus or specialized organelles
5. What are the roles of TFIID in eukaryotic transcription? Distinguish between transcription factors and
transcriptional activators.
− Transcription Factors (TFs)
o Help RNA Polymerase II position near the promoter in Eukaryotes
o We did’t ae a lot of the, ut e did ae oe
o TF II D is the primary one that interacts with RNA Polymerase
o It anchors itself around the -25 region and serves as a landing platform for RNA Polymerase to land on
o TF II D and many other TFs are necessary for the proper affinity and binding of RNA Polymerase
− Transcriptional Activator Proteins (TAPs)
o Proteins that bind to enhancer regions
o These regions are quite upstream from the start of transcription
o An TAP bound to an enhancer region will bend around and enzymatically interact with RNA
Polymerase, tapping it and giving it the green light to start transcription
6. We have discussed gain/loss of function mutations. How could either of these be explained by changes to
promoter sequences?
− Mutations in the promoter or enhancer region could increase or decrease affinity of their corresponding
proteins
− Mutation in promoter that makes it unrecognizable → LOF
− Mutation in enhancer that makes it unrecognizable → LOF
− Mutation in enhancer that makes for stronger affinity (or perhaps a duplication and the additive effect of
having more enhancer regions) → GOF
7. Distinguish between the roles of promoter sequences and enhancer sequences in eukaryotic gene expression. How
do promoters and enhancers differ in terms of their proximity to the coding region of a gene? What proteins bind
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Document Summary
Transcription, rna processing, and translation objectives: be a(cid:271)le to d(cid:396)a(cid:449) dna a(cid:374)d rna (cid:374)u(cid:272)leotides a(cid:374)d disti(cid:374)guish the(cid:373) f(cid:396)o(cid:373) ea(cid:272)h othe(cid:396) (cid:894)(cid:455)ou do(cid:374)"t (cid:374)eed to d(cid:396)a(cid:449) the se(cid:395)ue(cid:374)(cid:272)es of the (cid:374)it(cid:396)oge(cid:374) (cid:271)ases just the (cid:894)deo(cid:454)(cid:455)(cid:895)(cid:396)i(cid:271)ose a(cid:374)d the phosphate(cid:895) Dna: not all (cid:271)a(cid:272)te(cid:396)ial p(cid:396)o(cid:373)ote(cid:396)s ha(cid:448)e the e(cid:454)a(cid:272)t sa(cid:373)e dna (cid:374)u(cid:272)leotides (cid:449)ithi(cid:374) the (cid:862)(cid:272)o(cid:374)se(cid:374)sus se(cid:395)ue(cid:374)(cid:272)e(cid:863) at -10 and -35. Need consensus to have a generally agreed upon, widely recognized promoter sequence. B(cid:455) (cid:272)ha(cid:374)gi(cid:374)g the se(cid:395)ue(cid:374)(cid:272)es, (cid:455)ou affe(cid:272)t the affi(cid:374)it(cid:455) of the ig(cid:373)a fa(cid:272)to(cid:396) (cid:894)o(cid:396) tf ii d i(cid:374) euka(cid:396)(cid:455)otes(cid:895) a(cid:374)d that"s. If there were all the same sequences then they would all have the exact same level of expression going to allow for different levels of expression. Expression level is coded by -35 to -10 (in prokaryotes: explain the role of rna secondary structure in termination of transcription (hairpin) Initiation of transcription in eukaryotes is more complex than in prokaryotes, involving many proteins and dna sequences.