2. Chapter 13 Transcription

3. RNA in the Primeval World What came first proteins or nucleic acids? or chicken Or the……… EGG! Life’s Paradox…

4. 1981: Tomas Cech Discovered: n RNA could act as enzymes=Ribozymes! Ribozyme RNA Tetrahymena thermophila

5. RNA structure Reminder of RNA structure. What are differences between DNA and RNA? Review Question:

6. RNAs Functional transfer RNAs Vital for protein translation ribosomal RNAs Forms complexes with proteins Vital for protein translation Informational messenger RNAs Intermediates in decoding genes into proteins And now many more! TRADITIONAL CLASSIFICATION of RNAs

7. Additional functional classes of RNA n Small nuclear RNAs n Small nucleolar RNAs n Small cytoplasmic RNAs n Small Interfering RNAs n MicroRNA n  n  n  n  n  Molecule of the year 2002

8. RNA Transcription  ’  ’ 

9. The Basic Model Let’s look closely at the process of transcription. terminator

10. Transcription unit with more detail

11. Four key components of transcription n Promoter n Transcription start site n RNA coding region n The Terminator

12. Process of Bacterial Transcription n Initiation n Elongation n Termination

13. Prokaryotic Initiation

14.  Prokaryotic: RNA Polymerase Required for Initiation of Transcription Can only continue transcription ωω

15. RNA polymerase binds

16. Prokaryotic Elongation

17. The Search The Binding: “Closed Complex” The Unwinding: “Open complex” Transcription Begins: Sigma factor leaves RNA Polymerase ω

18. Transcription is always 5’ to 3’

19. Prokaryotic Termination

20. Transcription Termination n 2 mechanisms q rho dependent q rho independent

21. Rho Dependent Binding of rho protein Secondary RNA structure Rho protein has helicase activiity!

22. Rho Independent Speed bump

23. Eukaryotic Transcription

25. Eukaryotic Initiation

26. Promoter of RNA polymerase II Affects rate of transcription

27. Promoter recognition and transcription initiation ■BASAL TRANSCRIPTION APPARATUS □General Transcription Factors □RNA Polymerase □Mediator proteins ■Transcriptional Activator Proteins

28. General Transcription Factors (for example: for RNA Polymerase II) 1. TFIIA 2. TFIIB 3. TFIID 4. TFIIE 5. TFIIF 6. TFIIH

29. Binds to minor groove

30. Eukaryotic Transcriptional Termination n Protein dependent termination q But proteins binds DNA not RNA n Protein Independent q but no hairpin loop

31. n Eukaryotes n Arachae n Eubacteria Evolution and Regulatory Sequences TATA BINDING PROTEINS NO TATA BINDING PROTEINS