1. Prokaryotic Gene Regulation Beyond the Lac Operon

6. Manifestations of the Fertility Factor Manifestation Description Hfr The F element is integrated into the genome. When conjugation occurs, the F genes travel across the pilus, dragging the rest of the genome behind it. Eventually, the pilus breaks, so most often the entire genome is not transferred. The bacterial genome can be measured in minutes from the origin of transfer: The amount of time it takes for a particular gene to be transferred from one bacterium to another indicates how far it is from the origin of replication. F' Also called the F' episome. This is a small circular piece of DNA that contains the fertility genes and a few other genes. These other genes are transferred very efficiently from one bacterium to the next because the length of the transferred DNA is short enough that it can move across the breach before the pilus breaks. F This is a small circular piece of DNA carrying only the fertility genes.

10. Pathways Involve Multiple Genes Both biosynthetic and catabolic pathways involve multiple enzymes and thus multiple genes

12. A Complementation Example

27. A Diagram of the Lac Operon

28. Elements of the Lac Operon ELEMENT PURPOSE Operator (Lac O) Binding site for repressor Promoter (Lac P) Binding site for RNA polymerase Repressor (Lac I) Gene encoding lac repressor protein Binds to DNA at operator and blocks binding of RNA polymerase at promoter Pi Promoter for LacI CAP Binding site for cAMP/CAP complex

29. And Another Diagram

31. Induction of the Lac Operon

35. Action of CAP

39. Lac Operon Mutants GENOTYPE PHENOTYPE +IPTG -IPTG Wild Type + - Lac Z- - - Lac P- - - Lac O- + + Lac I- + + Lac I(s) - - Lac O-Lac I(s) + +

42. Diffusible Proteins Act Trans

43. DNA Binding Sites Act Cis

50. The Tryptophan Operon

52. Repression of the Tryptophan Operon