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Unformatted text preview: Elongation: RNA polymerase builds the RNA 2.4. Termination sequences: form hairpin loops in the RNA that destabilize RNA polymerase, and/or rho protein binds to a recognition site just upstream of the hairpin loop, moves downwards & separates the DNA & RNA. Fig. 8.11c In prok., no further modification of RNA, though 5 end has 3 phosphates on it. 2.5. There are 3 RNA polymerases in eukaryotes. RNA pol. II produces mRNA (& snRNA). Pol I and III are for tRNA and rRNA. 7 Modifications of RNA in eukaryotes, Figs. 8.13 & 14. The 5 methlyated cap RNA polymerase may go on for 100s of bases past the signal for the poly-A tail at 3 of the transcript. An enzyme complex cleaves the RNA just downstream of the signal and adds a set of As. Multiple RNA can be transcribed from the same gene in both euk. and prok. 2.6. Splicing out of introns in eukaryotes (see Figs. 8.15-.16). The spliceosome is made of snRNA & proteins. The 5 end of the intron is cut first & folded over to meet a branch point to form a lariat. Then the proteins....
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