During transcription, pausing can occur early in elongation. Where is pausing most likely to occur?

• A. Only in prokaryotes
• B. During initiation
• C. During termination
• D. Early during elongation (correct)

Answer: (D)

Pausing is a regulatory checkpoint that happens as RNA polymerase moves from starting transcription into productive elongation. Right after promoter clearance, the enzyme often slows or pauses within the first few dozen nucleotides of the transcript. This early elongation pause gives time for regulatory factors to act and for necessary processing steps to occur (for example, in eukaryotes, RNA capping is coordinated here). Because the pause is tied to the transition from initiation to elongation, it is most likely to occur early in elongation rather than during initiation or at termination. While pausing can happen in both prokaryotes and eukaryotes, the defining moment is the early stage after transcription has begun.