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RNA processing II
Question | Answer |
---|---|
rRNA splicing | Ribozyme mediated removal of IV sequence. Requires internal guiding sequence. cut at 5' splice junction creating 5'exon with OH group. Rho independent termination of transcription. |
mRNA splicing in Euk | 2 splice event: GU 5' and AG 3'. Pyrimidine tract that is highly rich in C/U, signal in intron. Branch site contains internal A which initiates 1st transesterfication. |
Alternating splicing | Generate multiple protein products from same primary transcript. Tropomyosin uses exon skipping. Calcitonin is an exon 4 related polyadenylation. |
Exonic Regulating Elements | Sequences that regulate the choice of certain exons & the exclusion of certain introns |
Beta-thalassenia | Nt change at an intron-exon junction which leads to aberrant splicing. Inadequate b-globin chains to pair with alpha. Mutation in intron creating new AG leads to errors in splicing. |
Myotonic Dystrophy | Autosomal Dominant. Instead of CGG there is CUG expansion. |
Sequestration | Mutant tri-nt repeat expansion binds and sequesters a splicing regulatory factor. hijacks & binds a paramount regulatory factor. |