A transcription bubble is a molecular structure formed during DNA transcription when a limited portion of the DNA double helix is unwound. The size of a transcription bubble ranges from 12 to 14 base pairs. A transcription bubble is formed when the RNA polymerase enzyme binds to a promoter and causes two DNA strands to detach.[1] It presents a region of unpaired DNA, where a short stretch of nucleotides are exposed on each strand of the double helix.[1][2]
^ abAlberts, Bruce; Johnson, Alexander; Lewis, Julian; Morgan, David; Raff, Martin; Roberts, Keith; Walter, Peter (2015). Wilson, John; Hunt, Tim (eds.). Molecular Biology of the Cell (6 ed.). Garland Science. pp. 306–307. doi:10.1201/9781315735368. ISBN9781315735368.