BIO 202 Lecture Notes - Lecture 30: Ribosome, Start Codon, Hydrolysis
24 Apr 2017
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Document Summary
Most eukaryotic genes and their rna transcripts have a long noncoding stretch of nucleotides that lie between coding regions. Pre-rna for eukaryotes contains introns and exons [unlike prokaryotes that are already matured] Pre-rna (cid:374)eeds to ha(cid:448)e a 5" (cid:272)ap a(cid:374)d poly-a-tails added in and introns sliced out. Exons need to be joined together when introns are removed. Exons are eventually expressed, usually translated into amino acid sequences. Spli(cid:272)i(cid:374)g, 5" (cid:272)appi(cid:374)g a(cid:374)d poly-a-tail takes place in the nucleus, where transcriptions happens. Spliceosome is a complex of rnas and proteins. Within spliceosome, base pairing between the pre-mrna and snrna promotes cleavage and ligation (splicing) Consensus sequences are at intron/exon junction and branch point. Ribozyme: rna molecule with enzymatic activity [like an enzyme] Some genes can encode more than one kind of polypeptide, depending on which segments are treated as exons during rna splicing. Such variations are called alternative rna splicing. You can generate different combinations on a single strand of gene.
