Practice question

Directionality defined relative to transcription start site +1. Polymerase moves progressively downstream, 3' along template strand, synthesizing RNA complementary. Therefore sequences situated toward terminator beyond +1 designated downstream region includes transcribed gene body, introns, termination signals, and often translational elements. During elongation, polymerase faces positive supercoiling ahead and negative behind migrating downstream. Understanding downstream polarity essential for mapping nascent transcript emergence, co-transcriptional folding, and coupling to translation in bacteria where ribosomes load downstream of polymerase as it advances toward terminator.