- Transcription is stopped at termination sites usually they contain “AT” repeats and the AG region that is palindromic and has AT's after. Because of this, the RNA transcription (product) can form a hair pin. 
- This hairpin causes an RNA polymerase to pause and likely causes a conformation change in RNA polymerase that causes it to release from the DNA. – but studies suggest this is a multi step process.
- Rho factor – some termination sites lack the similarities described above – the Rho factor terminates those sequences – it is a helicase that unwinds RNA, DNA and RNA double helices. It attaches to RNA and travels until it finds RNA polymerase that is paused and it pushes RNA polymerase that causes rebinding of DNA which ends transcription. 


Prokaryotic RNA Transcription (Termination )

- Transcription processed 5’ -> 3’ 
- In bacteria, transcription and translation occur nearly simultaneously because of the absence of the nucleus. These are typically the house keeping genes that are continually expressed.


Grand Valley State University

- Transcription is initiated by a promoter – about 40 base pair sized sequences starting on the 5’ end of the start site. 
- -10 and -35 sequence is  the promoter sequence, while initiation occurs downstream  (add image)
- Initiation requires formation of transcription bubble 
- Sigma factors – determine which genes are transcribed. 
– In some bacteria, sigma factors can differentiate when genes are expressed as early, middle, and late genes. 


Prokaryotic RNA transcription (Initiation)

Voet, D., Voet, J. G., & Pratt, C. W. (2013). Chapter 26: Transcription and RNA Processing. In Fundamentals of biochemistry: Life at the molecular level (4th ed., pp. 919-957). Hoboken, NJ: Wiley. Retrieved April 4, 2021, from archive.org.

Learn Before

Related

Learn After