1. Transcription *RNA polymerase (from E. coli )  2  ’  Core Sigma factor Holoenzyme

2. Transcription Functions of a prokaryotic promoter: 1.ON/OFF Switch 2.Speed Switch 3.Alignment

3. Transcription Initiation

4. Transcriptional Elongation:

5. Termination of Transcription Inverted Repeats and Hairpins The repeat at right is symmetrical around its center shown with a dot A transcript of this sequence is self- complementary –Bases can pair up to form a hairpin as seen in the lower panel

6. Termination of Transcription *Rho-independent termination

7.  factor Termination of Transcription *Rho-dependent termination

8. RNA Polymerase binding *Constitutive or basal level transcription

9. Allosteric activation of RNA polymerase

10. Inhibition of transcription DNA-protein interactions

11. Negative Control of the lac Operon

12. Proposed CAP-cAMP Activation of lac Transcription