Biology 1002B Lecture Notes - Lecture 17: Intron, Proteasome, Microrna
11 Apr 2017
School
Department
Course
Professor
Document Summary
Outcome is that appropriate proteins within a family are synthesized in cell types/tissues they function most optimally in. Variations in the rate of mrna breakdown: involves regulatory molecule (steroid hormone) directly/indirectly affects mrna breakdown steps (slows or increases rate of the steps) Post-transcriptional control by masking proteins: masking proteins that bind to mrnas to make them unavailable for protein synthesis. Regulation of gene expression by small rnas: rna interference (rnai) noncoding single-stranded rnas can bind to mrnas and affect their translation, includes micrornas and short interfering rna. Mirna produced by rna encoded in genome, sirna produced from double stranded rna not encoded by nuclear genes: mirna-induced silencing complex (mirisc) binds to sequences in 3" utrs of target mrnas. If mirna and mrna pair imperfectly, double-stranded segment formed between mirna and mrna blocks ribosomes from translating mrna. Target mrna is not destroyed, but its expression is silenced.
