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Steps>>Transcription - snap + easily meltable...

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*ALL SEQUENCES GIVEN FOR SENSE STRAND 5’ – 3’!* Prokaryotes » Initiation 1. Promoter site – 1) binding site for RNA polymerase [-35] σ factor, 2) site for unwinding [- 10 - AT-rich], 3) mark exact start point [+1 - A] 2. Holoenzyme [RNA Polymerase’s core enzyme + σ factor] – binds to promoter, σ factor falls off, unwinds DNA » Elongation 3. RNA Polymerase – reaches coding region to make mRNA [looks like sense strand], moving along template strand 3’ to 5’, adding ribonucleotides by base pairing 5’ to 3’ on mRNA strand [3’ end] 4. NusA – protein – binds to RNA Polymerase [core enzyme] to slow act of transcription, slow enough for ribosomes to keep up [coupled transcription and translation] » Termination [2 ways depends on gene at end] 5a. Rho-Dependent Termination rho-binding site on mRNA was transcribed into existence, rho [helicase – 5’ to 3’] breaks H bonds between RNA and DNA 5b. Rho-Independent Termination – 2 parts – 1) stem loop 2) string of U’s [A’s on DNA]; force of
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Unformatted text preview: snap + easily meltable U-A H bonds = rip RNA off of DNA 6. RNA Polymerase dissociates after a) rho helps to dissociate b) loosing RNA Eukaryotes no NusA, no factor, more variation [substitution of conserved sequences] Initiation 1. Promoter site - 1) binding site for RNA polymerase [GC & CAAT boxes - TFs], 2) site for unwinding [-25 TATA box], 3) mark exact start point [+1 - A] 2. Transcription Factors [TFs] binds to promoter site at specific conserved sequences each RNA P has a set of TFs 3. RNA Polymerase recognizes/binds to complex of TFs [big complex of TFs & RNA P cover entire promoter Elongation [3 different RNA Polymerases specific to RNA] no NusA 4. RNA Polymerase RNA P I [rRNA except 5s], RNA P II [mRNA], RNA P III [small RNAs tRNA, 5s rRNA] transcribes certain set of genes [3 RNA Ps 3 different categories of promoter] Termination 5. Different for each RNA Polymerase...
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This note was uploaded on 02/19/2012 for the course BIO 325 taught by Professor Saxena during the Fall '08 term at University of Texas at Austin.

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