Transcription

promoter

DNA sequence where RNA polymerase binds & initiates transcription

(prokaryotes) promoters are located at

10 & 35 upstream (towards 5’ end)

promoter sequences are recognized by

sigma factor

elongation overview

as RNA polymerase elongates the mRNA chain, it untwists DNA to create another transcription bubble

rho-dependent termination

Rho protein tags along behind the RNA polymerase

RNA polymerase encounters long G-chain → stalling

Rho protein collides with RNA polymerase

mRNA released from transcription bubble

rho-independent termination

polymerase encountered C-G rich region

mRNA folds in on itself to form hairpin with complementary C-G binding

polymerase stalls & transcribes A-T rich region

3 diff RNA polymerases in euks

pol I - rRNAs

pol II - mRNAs

pol III - tRNAs

promoter region for RNA pol II in eukaryotes

TATA box 

located 25-35 bases relative to initiation site 

eukaryote elongation overview

majority RNA pol II

same as proks

FACT

protein complex facilitates chromatin transcription

pulls histones away from DNA template as RNA polymerase moves along it

termination

RNA pol I & III require termination signals

3 parts of RNA processing in euks

1. CAP at 5’ end to prevent degradation

2. 3’ Poly-A tail prevent degradation & create binding site for protein necessary to export mRNA to cytoplasm

3. introns spliced from exons via spliceosomes

pre-rRNAs are

transcribed, processed, assembled into ribosomes in nucleolus

pre-tRNAs are

transcribed & processed in nucleus

released into cytoplasm