- Transcription in eukaryotes is carried out by three RNA polymerases (RNAP I, II, III) that synthesize different RNA molecules and require transcription factors. - RNAP II transcribes protein-coding genes and initiation requires promoter elements like TATA boxes located upstream of genes. - Introns, or intervening sequences, are found within most eukaryotic genes and can exceed exon sequences in length. Introns are excised through different splicing mechanisms for mRNA, tRNA, and rRNA. - Splicing of mRNA introns involves a spliceosome complex containing small nuclear RNAs that catalyzes two transesterification reactions joining exons.