LIFESCI 3 Chapter Notes - Chapter 16.2: Addition Reaction, Branch Point, Snrnp
Document Summary
Pre-mrna is spliced to produce mature, translation competent mrna. Rna splicing shows how protein-coding sequences evolve and cause diseases. Specific phosphodiester bonds are broken and joined to excise introns. Spliceosome: complex of rna and proteins responsible for mrna splicing. Determines whether a given set of splice sites will be used. Some introns in mitochondrial, chloroplast, and bacteriophage transcripts are self- splicing. Catalyze their own excision from a primary transcript without proteins. Eukaryotic mrnas are synthesized as precursors containing introns. Bacteria: polypeptide chain is encoded by a dna sequence that is colinear with the amino acid sequence. No interruption in the dna template until polypeptide information is complete. Most of the rna in eukaryotic primary transcripts is degraded before leaving the nucleus. Regions of complementarity interspersed with looped out regions of dna that do not base pair with mrna. Introns can regulate the amount of mature mrna produced. Some introns include open reading frames that encode regulatory proteins.
