Lecture 23 done

Lecture 23 done - Lecture 23: Eukaryotic RNA Processing 2...

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Lecture 23: Eukaryotic RNA Processing 2 1. Does the “one gene - one protein” hypothesis hold true in eukaryotes, as it does (mostly) for prokaryotes? Explain. -In eukaryotes: “complex genes” one gene Several different transcripts/ mRNAs (complex transcripts) Several different proteins (isoforms) with several different functions. -In humans, about 35-60% of genes are complex -Generated by: alternative splicing of pre-mRNAs; alternative 3’ end processing (cleavage & polyadenylation); and finally alternative promoter usage 2. How does alternative splicing contribute to protein diversity? Alternative splicing allows multiple proteins to be produced from a single strand of mRNA. With different combinations of different exons being removed, as well as introns, many different proteins can be produced from a single mRNA. 3. How does alternative splicing regulation contribute to tissue-specific gene expression? -When specific spliced products of a given gene are favored over others in specific tissues, at specific developmental stages or in response to specific physiological stimuli. Requires specific RNA-binding proteins “splicing regulators” that determine which intro/exon junctions are favored by the splicing machinery. -Alternative splicing can be regulated by RNA-binding proteins that bind to specific sequences near regulated splice sites. Splicing repressors may sterically block the binding of splicing factors to specific sites in pre-mRNAs or inhibit their function. Splicing activators enhance splicing by interacting with splicing
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This note was uploaded on 06/08/2009 for the course BCH 120 taught by Professor Luben,norman,henry during the Spring '09 term at UC Riverside.

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Lecture 23 done - Lecture 23: Eukaryotic RNA Processing 2...

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