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lecture_6__05 - A few differences between eukaryotic and...

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A few differences between eukaryotic and prokaryotic transcription: in eukaryotic cells, RNA polymerase has many more subunits and adaptor proteins which help the enzyme to recognize the promoter and to respond to stimuli regulatory elements in eukaryotes can be very far away (millions of base-pairs) from the gene that they regulate, while prokaryotic promoters do not have complex regulatory regions far away from the ORF. Eukaryotic regulatory elements are usually called "enhancers " the eukaryotic equivalent of the -10 element is conserved in eukaryotes and is called the "TATA box ", but the other sequence elements are not conserved there are no operons in eukaryotic cells; each gene has its own promoter in eukaryotes, the distance between the TATA box and the transcriptional start site is variable, but usually about 30 nucleotides upstream of the start eukaryotes have 3 nuclear RNA polymerases; Pol II transcribes mRNA
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Transcription initiation:promoter elements a sequence element containing the sequence TATA (or other TA-rich sequence) is usually present in the promoter region of a gene, upstream of the transcription start site. A specific complex of transcription factors (TFIID in eukaryotes) binds at the “TATA box” and then recruits the larger RNA polymerase complex. The assembly of all of the factors in the RNA polymerase “ holoenzyme ” induces transcription initiation Fig. 17.7
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