LIFE 120 Lecture Notes - Lecture 32: Rna Splicing, Alternative Splicing, Stop Codon
Document Summary
Chapter 14 lecture 2 with clicker questions in red. Transcription in eukaryotes: transcription occurs in the nucleus. Mrna is transported to the cytoplasm for translation on ribosomes. Rna processing: when - enzymes in the eukaryotic nucleus modify pre-mrna (rna processing) before the genetic messages are dispatched to the cytoplasm, where - pre-mrna is modified in the nucleus, two types of modifications: During rna processing, both ends of the primary transcript are altered. (capping & tailing) Alteration of mrna ends: these modifications share several functions. Facilitating the export of mrna to the cytoplasm. Helping ribosomes attach to the 5 end. Alternative rna splicing: many genes can give rise to two or more different polypeptides, depending on which segments are used as exons. Genes can encode more than one kind of polypeptide if different exons are used. Permits more proteins from smaller genomes: this process is called alternative rna splicing, spliceosomes. Alternative splicing is carried out by spliceosomes.
