Topic overview

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Transcription synthesizes RNA in the 5′→3′ direction while reading the DNA template 3′→5′. Prokaryotes use one RNA polymerase, with sigma factor supporting promoter recognition and initiation. Eukaryotes use distinct RNA polymerases for major RNA classes, and general transcription factors help initiate transcription at core promoters. The topic also considers how distal regulatory elements and chromatin state influence transcription. Eukaryotic pre-mRNA is processed through capping, splicing, and addition of a poly-A tail; alternative splicing can increase protein diversity. Differences in termination, cellular location, and mRNA organization help distinguish prokaryotic from eukaryotic transcription. Selected clinical and pharmacological examples connect transcription mechanisms to disease and drug action.