1. Microbial Genetics (Micr340) Lecture 15 Regulation of Gene Expression

2. Types of regulation Transcriptional regulation (most common) occurs through proteins called transcriptional regulators Negative regulation: a mutation that inactivates the regulatory gene will allow transcription of an operon, even in the absence of inducer Positive regulation: a mutation that inactivates the regulatory gene will prevent transcription, even in the presence of inducer Post transcriptional regulation Translational regulation

3. Negative regulation lac operon example

4. Operators for lac operon

5. Control region for lac operon

6. Negative regulation gal operon example

7. Effect of additional copies of operator regions

8. Tryptophan biosynthetic operon

9. Negative Regulation of Tryptophan (trp) operon

10. Positive regulation L -ara operon example

11. AraC: A positive regulator & an antiactivator

12. Maltose operons

13. Regulation by attenuation of transcription

14. Attenuation in trp operon

15. Attenuation in trp operon (continued)