6 Questions
What is the characteristic feature of a Rho-independent terminator?
It has a G-C rich stem.
What is a key protein involved in Rho-dependent termination?
Rho factor
How many bases are typically found after the loop in a Rho-independent terminator?
7-9 bases
What is the approximate size of the Rho factor protein?
46-kD
Which activity is associated with the Rho factor in facilitating Rho-dependent termination?
Helicase activity
What happens to chain elongation when RNA polymerase encounters a transcription-termination signal?
It stops.
Study Notes
Rho-Independent Termination
- Characterized by a G-C rich stem and a 7-9 base U-run after the loop
- U-DNA pairing is very weak, allowing for dissociation
Rho-Dependent Termination
The Rho Factor
- A 46-kD protein that is active as a hexamer
- Binds to specific sequences on RNA (50-90 bp)
- Has helicase activity, separating RNA-DNA
How it Works
- Binds to RNA tail and moves along the transcript until it catches up to the polymerase (Hot Pursuit Model)
- Causes RNA-DNA separation through its helicase activity, leading to termination
Key Points of RNA Synthesis
- Occurs in three stages: initiation, elongation, and termination
- RNA polymerases are complex multimeric proteins that catalyze transcription
- RNA chain elongation occurs within locally unwound segments of DNA
- Transcription-termination signals halt RNA synthesis
- Transcription, translation, and mRNA degradation often occur simultaneously in prokaryotes
Learn about rho-independent and rho-dependent termination mechanisms in transcription, including the role of the rho factor and its helicase activity.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
