MCB 250 Lecture Notes - Lecture 12: Ribosomal Rna, Polyadenylation, Cytoplasm

• School: University of Illinois
• Department: Molecular and Cell Biology
• Course: MCB 250
• Professor: J Slauch

Document Summary

Rna processing rrna operons are not translated (which means that rho should terminate transcription: this is actively prevented, antitermination gives a pre-rrna transcript, the pre-rrna transcript is then processed mrna processing in eukaryotes. The 5" cap of eukaryotic mrnas: occurs immediately after the 5" end is made before transcription is completed, functions, important for splicing, protection from rnases increased stability, enhances efficiency of translation cap binding. Protein: required for efficient transport from the nucleus. Polyadenylayion of the 3" end: two step process, 1) cleavage and 2) addition of poly a, recognition sequence. 5"-------//----aauaaa- ~20nt (gu rich)---: about 200 as are added, can occur prior to completion of transcription can be >500 bp from 3" end of the transcript, fucntions, protection from rnases increased stability. When polya is finally lost mrna is degraded: enhances translation. Pab (poly a binding protein) mrna splicing. Splicing of eukaryotic trnscripts: many eukaryotic rnas have introns that must be removed, pre-mrna 0- ~60 introns.