Transcription bubble.

Definition

The transcription bubble is a localized region where the DNA double helix unwinds, allowing RNA polymerase to access the template strand for RNA synthesis. It typically encompasses about 17 base pairs and moves along the DNA as transcription proceeds.

5 Must Know Facts For Your Next Test

1. 1. The transcription bubble forms at the promoter region of a gene where RNA polymerase binds.
2. 2. During prokaryotic transcription, the bubble remains approximately 17-18 nucleotides in length.
3. 3. Both the initiation and elongation phases of transcription involve the formation of a transcription bubble.
4. 4. The RNA-DNA hybrid within the bubble is usually around 8-9 base pairs long.
5. 5. Termination of transcription involves the closing of the transcription bubble and release of the newly synthesized RNA molecule.

Review Questions

• 1. What is the typical length of a transcription bubble in prokaryotic cells?
• 2. At which phase(s) of transcription does the transcription bubble form?
• 3. How does termination affect the state of a transcription bubble?

Related terms

RNA Polymerase: An enzyme that synthesizes RNA from a DNA template during transcription

Promoter:

A specific DNA sequence where RNA polymerase binds to initiate transcription

Termination Site: A region in DNA that signals for RNA polymerase to stop transcribing and release the newly made RNA