Lecture 3 Gene transcription Part3 mRNA processing

In this lecture segment, we examine post-transcriptional mRNA processing after RNA polymerase release, focusing on key steps including 5′ capping (m⁷GpppN formation via the unique 5′–5′ triphosphate linkage), 3′ poly-A tailing (addition of 200–300 adenylates), and splicing (intron removal with lariat formation to join exons). We also explore RNA editing mechanisms—both template-independent (ADAR: A-to-I via inosine formation; APOBEC family) and template-dependent (Trypanosoma brucei GUIDE RNAs for U insertion/deletion)—and assess their critical roles in human biology.