The processing of ribosomal and transfer RNA

The processing of ribosomal and transfer RNA.a) A large transcript is cleaved to produce rRNA and tRNA in E. coli. (b) Human rRNA genes are part of 40-kb repeating sequences that each produce three rRNAsThe processing of ribosomal and transfer RNA.a) A large transcript is cleaved to produce rRNA and tRNA in E. coli. (b) Human rRNA genes are part of 40-kb repeating sequences that each produce three rRNAs

(a) E. coli RNA-coding gene 3! 165 tRNA 23S rRNA SS tRNA DNA 5' rRNA rRNA 0 Transcription produces lntervening a 305 pre-RNA. sequence Mm s' _3' 305 ppe-RNA' 16S tRNA 23SrRNA ss tRNA transcrlpt rRNA rRNA a RNA cleavage releases rRNAs and tRNAs. + + Ribosomal RNA 165 235 SS and - + - Transfer RNA tRNA tRNA (b) Human rRNA transcriptional unit, 13 kb Intergenic spacer l—TS |TS1 ITSZ .H. “27 kb .I DNA5’__-__I__—___/l___3' 285 o Transcription synthesizes a 45$ pre-rRNA transcript. Pre-rRNA 9—? 455 pre-rRNA transcript 185 5.85 285 a Pre-RNA cleavage produces three rRNAs. 5.85 - + h Ribosomal RNA 185 285