Presentation is loading. Please wait.

Presentation is loading. Please wait.

Gene regulation Biology, 5 October 2010 Donald Winslow Operons in prokaryotes.

Similar presentations


Presentation on theme: "Gene regulation Biology, 5 October 2010 Donald Winslow Operons in prokaryotes."— Presentation transcript:

1 Gene regulation Biology, 5 October 2010 Donald Winslow Operons in prokaryotes

2 Gene regulation in prokaryotes References: Griffiths et al., 9th ed., Ch. 10, pp Hoefnagels, Biology, 1 st ed., Ch. Pp Klug et al., Concepts of Genetics, 9th ed., Ch. 17 pp , ,

3 Regulatory proteins & binding sites on DNA Regulatory proteins Domains Allosteric site Binds to allosteric effector Presence of effector reflects conditions in cell DNA-binding domains binds to binding site on DNA Sometimes other sites bind to other regulatory proteins Binding sites on DNA Promoter is recognized by RNA polymerase

4 Prokaryotic gene regulation Switch operon on or off in response to stimuli Positive regulation Activator binds to activator-binding site Negative regulation Repressor binds to operator prevents transcription

5 Lactose metabolism in E. coli Repressor gene is transcribed to produce repressor protein. When lactose is absent, repressor protein binds to operator and prevents transcription of structural lactose-metabolism genes. When lactose is present, lactose binds to repressor protein and changes its shape so it can no longer bind to operator. Transcription of structural lactose-metabolism genes is blocked.

6 Catabolite repression


Download ppt "Gene regulation Biology, 5 October 2010 Donald Winslow Operons in prokaryotes."

Similar presentations


Ads by Google