After completing chapter 21 (part 1), students will be able to: Know the central dogma of Biology; know what housekeeping genes are; know the different type of RNA and there roles in the cell; know the relationship between RNA steady state abundance, rate of synthesis, and stability; know what happens during the different stages of replication;. | Chapter 21 (part 1) Transcription Central Dogma RNA Content of E. coli Cells type Steady State Levels Synthetic Capacity Stability rRNA 83% 58% High tRNA 14% 10% High mRNA 3% 32% Very Low E. Coli RNA Polymerase RNA polymerase core enzyme is a multimeric protein a2,b, b’, w The b’ subunit is involved in DNA binding The b subunit contains the polymerase active site The a subunit acts as scaffold on which the other subunits assemble. Also requires s-factor for initiation –forms holo enzyme complex Site of DNA binding and RNA polymerization General Gene Structure 5’ 3’ Transcribed region terminator Promoter Gene Promoters Other s-Factors Standard genes – s70 Nitrogen regulated genes – s54 Heat shock regulated genes – s32 Transcriptional Initiation Closed complex Open complex Primer formation Disassociation of s-factor Pausing induces termination 3’end tends to be AU rich easily to disrupt during pausing. Leads to disassembly of RNA polymerase complex Rho Dependent Termination rho is an ATP-dependent helicase it moves along RNA transcript, finds the "bubble", unwinds it and releases RNA chain Eukaryotic RNA Polymerases type Location Products RNA polymerase I Nucleolus rRNA RNA polymerase II Nucleoplasm mRNA RNA polymerase III Nucleoplasm rRNA, tRNA, others Mitochondrial RNA polymerase Mitochondria Mitochondrial gene transcripts Chloroplast RNA polymerase Chloroplast Chloroplast gene transcripts Eukaryotic RNA Polymerases RNA polymerase I, II, and III All 3 are big, multimeric proteins (500-700 kD) All have 2 large subunits with sequences similar to and ' in RNA polymerase, so catalytic site may be conserved Eukaryotic Gene Promoters Contain AT rich concensus sequence located –19 to –27 bp from transcription start (TATA box) Site where RNA polymerase II binds Transcription Factors TFAIIA, TFAIIB – components of RNA polymerase II holo-enzyme complex TFIID – Initiation factor, contains TATA binding protein (TBP) subunit. TATA box recognition. TFIIF – (RAP30/74) decrease affinity to non-promoter DNA | Chapter 21 (part 1) Transcription Central Dogma RNA Content of E. coli Cells type Steady State Levels Synthetic Capacity Stability rRNA 83% 58% High tRNA 14% 10% High mRNA 3% 32% Very Low E. Coli RNA Polymerase RNA polymerase core enzyme is a multimeric protein a2,b, b’, w The b’ subunit is involved in DNA binding The b subunit contains the polymerase active site The a subunit acts as scaffold on which the other subunits assemble. Also requires s-factor for initiation –forms holo enzyme complex Site of DNA binding and RNA polymerization General Gene Structure 5’ 3’ Transcribed region terminator Promoter Gene Promoters Other s-Factors Standard genes – s70 Nitrogen regulated genes – s54 Heat shock regulated genes – s32 Transcriptional Initiation Closed complex Open complex Primer formation Disassociation of s-factor Pausing induces termination 3’end tends to be AU rich easily to disrupt during pausing. Leads to disassembly of RNA polymerase complex Rho Dependent Termination rho is an .
