Lec%2016_W11 - Questions:whyareDicerandRiscenzymes...

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Questions: why are Dicer and Risc enzymes  present in organisms? RNAi is a defense against foreign nucleic acids. viral infection RNAi is a way that organism naturally turn genes on and  off. Recent discovery of specifically expressed small RNA  sequences called microRNAs (miRNAs) that are  encoded in genome and are used to regulate  development (ex.  lin-4 )
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microRNAs Many organisms, including mammals express  endogenous, small (19–25-nt), non-coding RNAs that  are known as microRNAs (miRNAs or miRs) which have  important roles in widespread functions including  development, cell proliferation, and apoptosis.  But micro RNAs not very specific – all they need is to  match  an 8 nt “seed” sequence, usually in the 3’ UTR of  the target gene – this is not very specific.  Thus one  microRNA can effect many genes. Unlike siRNAs, miRNAs do not usually initiate the RISC-
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This note was uploaded on 04/10/2011 for the course BIMM 101 taught by Professor Butler during the Spring '08 term at UCSD.

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Lec%2016_W11 - Questions:whyareDicerandRiscenzymes...

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