Transcription bubble

A transcription bubble is a molecular structure that occurs during the transcription of DNA when a limited portion of the DNA double strand is unwound. RNA polymerase (Main Article: transcription) may then bind to the exposed DNA and begin synthesizing a new strand of RNA. As RNA polymerase progresses down the DNA strand in the 3' to 5' direction, more of the DNA double strand is unwound upstream of the polymerase while DNA downstream of the polymerase re-anneals, moving a transcription bubble in the process that may be seen with specialized staining techniques, spectroscopy or microscopy.

See also: transcription factors, transcription initiation