Steps in RNA synthesis 2:elongation The sigma factor is released Sigma during elongation. 5 3 3 5' Transcription begins; Elongation:RNA polymerase moves down the DNA chain,causing temporary sigma released opening of the double helix..a延长阶段 5 3 3 5 RNA chain 5 growthElongation: RNA polymerase moves down the DNA chain, causing temporary opening of the double helix.延长阶段 The sigma factor is released during elongation. Steps in RNA synthesis 2: elongation