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5 Cards in this Set
- Front
- Back
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define long noncoding RNA (lncRNA) |
lncRNA=are non-protein coding transcripts longer than 200 nuclotides -they are invovled in regulating gene expression at the level of transciption, spicling and translation |
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describe how X-inactivation occur in mammals,include the role of Xist |
Xist is a lncRNA. that is required for mammalian dosage compenstaion by X- inactivation -on a locus on the X chromosome called X-inactivation center(Xci) produces a 17kb lncRNA called Xist -Xist is transcribed from only one of the X Chromosomes early in development of the embryos -chromosome producing Xist is inactivated by Xist acting in cis to coat that chromosome leading to the formation of heterochromatin (by catalyzing histone modification) |
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describe the steps in splicing, include the roles of splice donors, splice acceptors, branch sites, snRNAs and snRNPs |
occur co-transciptionally 1.snRNA binds to mRNA 2.U1 and U2 bind to 5' splice donor site and branch site repectivley 3.binding of U4,U5 and U6 snRNPs 4.5' end of intron is bonded to A at branch point 5.3'splice acceptor site is cut and 2 exon ligates 6.the excised intron,which has a lariat (lasso) shape, is degraded |
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describe the 5 types of splicing |
1.Exon skipping/inclusion 2.alernative 3' splice sites 3.Alternative 5' splice site 4.mutually exclusive exons 5.intro retention |
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describe the way alternative spliceing can be regualted by both cis and trans acting factors |
??? |
