Eukaryotic Transcription Unit 3 PDF

unit 3 : eukaryotic transcription * has 3 RNA polymeraze (RNAP) * located inside the nucleas * eukaryotes ↳ have more DNA · includ...

unit 3 : eukaryotic transcription * has 3 RNA polymeraze (RNAP) * located inside the nucleas * eukaryotes ↳ have more DNA · includes chromating condensed = no transcription relaxed = transcription present * properties of the 3 RNA polymerases RNAD I RNAP 11 RNAP II location nucleolus nucleoplasm nucleoplasm RNA produced URNA precursors of mRNA tRNA , rRNA and and SnRNAs SuRNAs [ sensitivity to resistant 50 % inhibition 50 % inhibition alpha amantin slightly sensative I sensitivity to very sensitive slightly sensitive actin D myosin them apart - kills by blocking transcription and used to tell each of -produced 2 mushrooms amanita phalloidis and amanita bisporigena o produces toxins & antibotic  of * elements eukaryotic transcription ↳ cis elements · DNA -> > promoters · basel promotor elements of DNA > - peice containg some genes · enhancers ↳ trans acting elements · proteins that bind to cis elements · RNA polymerase · transcription factors * what trangenesis ? is ↳ the INA/gene adding fixing something or in also called genetically modified organism (GMO) * structure of class 11 gene ↳ known as promoter ↳ regulatory elements can be upstream or downstream far away or upstream transcription termination site Promoter ↑ intron A ↑ intron B & ↑ b b * b upstream b exon 1 downstream exon 2 regulatory transcription initiation site u element b called enhancors * structure of class 11 promoters and their control elements ↳ all are core promoters · has > - proximal promoter elements > - TATAbOX > - initiator element Sequance Factor TATA box TATAAAA tata binding protein (TBP) box binding factor/necrosis factor CAAT GGCCAATCT CAAT GCbox GGGCGG Stimulatory protein / (SPI) octamer ATTTGCAT Oct specific to lymphoid cells ATF GIGACGT ATF * TATA box ↳ it is conserved sequance recognized by specific protein ↳ for transcription very important ↳ located 26-34 bpupstream transcription initiation site * alternative eukaryote promoter elements ↳ initiator +1 T · weak consensus surround the initation site R- means purine means pyrimidineany nucleotide ↳ CpG Islands · CG rich stretch > - 100bp from start site · not highly active in promoters * modulating eukaryotic transcription ↳ promoter proximal elements · located between -50 and -100 · close to the promoter · their position and orientation has to be maintained ↳ ennancor elements · can happen far from the gene ( phospholerate activity - DNA · LAP30 and RAP74 subunits] > - interacts with DNA at 5' binds"to polymerase and interacts with TFIIB · has enzymatic activity needed to unwind DNA helit] helicase · starts transcription initiation to transcription elongation can be recruted · by polymase to help restart transcription · ATP dependent ↳ TF11H · unwinds DNA at the transcription start point · ATP dependant DNA helicase · phosphorylates RNA polymerase · releases RNA polymerase from the promoter * assembly of RNApII preinitiation complex 1 TFIID J- recognizes TATA box 2 TFIIA]- interact with TBP 3 TFllB] > binds with polymeraze ↑ TFIIF]- interact with polymeraze outside DNA 5 TFIH] kinase with phosphorelase  of the from * release polymerase promoter and inition of transcription ↳ TFIIH adds phosphate group so it loosens the interactions between and TF IID polymeraze ↳ then for elongation goes on * recruitment of the preinitiationComplex TATAless Promoter ↳ TAf interacts with SPI so TFIID will be indirectly bonded to the promoter ↳ TFIID Comes befor TFIIB otranscription factors associated with TATA binding protein * structural organization of the genes coding for RNAs ↳ RNAPI recognizes only one promoter ↳ operon has about 200 copies in human ↳ enzymes that cut RNA · IGS > - intergenic Spacer · ETS > - transcribed extragenic spacer · ITS > - transcribed intragenic spacer regulation of the transcription of RNAPI & in mammals there is a transcription factor called TIF-1A · found in actively dividing cells but absent in nondividing cells & TIF-IA abundant · polymerase I high transcription ↳ TIF-IA IOW · polymerase / low transcription ↳ it interacts with polymerase ↳ required to catalyse the formation of the first phosphodister bond Greleased after the transcription and re used for the next transcription * transcription termination ↳ transcription stops in the intergenic region (IGS) at one of the 18 termination sites located about 256 bp downstream of the mature RNA ↳ transcription termination sites are called sal and have this sequence · AGGTCGACCAGATNTCCG · the sequence function is oreintation dependent it requires the binding of the ↳ transcription termination factorI (TTF1) on the sal sequence transcription the sall ↳ TTFI block around lobp upstream sequance ↳ exonuclease associated to RNAPI cuts 11 bases at 3