Chapter 18 Regulation of Gene Expression

Chapter 18 Regulation of Gene Expression - Chapter 18...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 18 Regulation of Gene Expression Prokaryotic Regulation of Genes Microbes used as model systems Bacteria (prokaryotes) Escherichia coli E. coli Viruses (require host cells to make proteins and reproduce) Used to identify that genes are DNA and to explain mechanisms of transcription and translation Bacterial respond to environment by regulating transcription - operon Negative control of Gene Expression Trp Operon System – repressible operon In E. coli anabolic pathway to synthesize tryptophan (5 genes code of enzyme subunits required in the metabolic pathway) Trp operon = 5 genes + promoter (where RNA polymerase binds) Operator – switch is site of repressor protein binding site trp repressor – product of regulatory gene corepressor - tryptophan (as it accumulates in cell acts to turn off synthesis) when tryptophan binds to repressor protein which binds to operator no mRNA is made = operon off Lac Operon System- inducible operon regulatory gene codes for repressor protein RNA polymerase binds to DNA promoter region Operator (switch) Region of DNA strand between promoter and enzyme coding genes Repressor - protein binds to operator to block RNA polymerase
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

Chapter 18 Regulation of Gene Expression - Chapter 18...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online