Ch 3.3 Transcription- Mechanisms Flashcards
Where does transcription occur in Eu and Bac
Eu nucleus
Bac cytoplasm
Where does translation happen in Eu and bac
Eu and bac cytoplasm
Is rna processed in Eu or bac
Eu yes
Bac no
Transcription process
3
1) rna pol binds/ assembles at gene promoter
2) transcription starts and added downstream (+1 site / transcription start site)
3) passes through terminator then ends
Rna pol
3
Reads (3-5)
Made 2 subunits
Rna pol separates dna strands, makes rna, closes dna behind it
Promoter
2
Where rna pol binds/ initiate transcription
Used to bind sigma factor protien (use to recruit rna pol )
Promoters in bac
4
-10, -35 refers position upstream location +1 site
1) sigma factor binds promoter recruits rna pol complex
2) rna pol separates dna strands starts adding rna nucleotides at +1 site
3) sigma factor recruits and rna pol continues down stream, make rna chain
Holoenzyme
Sigma factor and rna pol
-10,-35 boxes
Define which direction the sigma factor binds and where rna pol faces when it binds
Define template strand
How tightly sigma factor binds form transcription control
Promoters Eu
TATA box
Other upstream sequences called enhancers: enhance initiation of transcription
How to recruit rna pol in Eu
TATA binding protein binds tata box
Other proteins begin assemble together around it (general transcription factor)
Basel transcription complex
Min protein assembly needed initiate transcription
Rna pol, TBP, general transcription factors
Transcription start site
Where transcription starts in Eu
What controls gene expression
Promoter
Terminator in bac
Stops after terminator
Growing rna forms hairpin signal rna pol to stop and release
Terminator Eu
Length after terminator transcribed varies
Multiple thing affect
Where do Dna binding proteins bind?
Base pairs (especially major grove) have lots atoms for it to bind
how strongly proteins bind to DNA determine…
If it’s function is successful (ex recuit) rna pol
Transcription control can be regulated by
How often/ tightly Sigma factor sticks to dna promoter
Promoter sequences
2
Diff sequences can bind with sigma factor more/less tightly
Not all promoters equal
What is invoked in Eu rna processing
3
1) splicing
2) 5’ capping
3) poly- adenylate tails
Splicing in Eu
3
Non coding introns taken out left with only exons
Coding sequence usually start/ end with exons
Sometime exons removed resulting in splice variants
What are the 5’ cap and 3’ poly-A tail for
Increase stability
Help regulate transcription
Cap used for protein binding
Help export mRNA from nucleus
Types mRNA
Primary
Mature: final mRNA ( needs sliceosome (rna and proteins))
