18 Lectures PPT for Eukaryotic Gene Expression 
Chapter
18
Regulation of Gene
Expression
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: Conducting the Genetic
Orchestra
• Prokaryotes and eukaryotes alter gene expression in response to their changing environment • In multicellular eukaryotes, gene expression regulates development and is responsible for differences in cell types
• RNA molecules play many roles in regulating gene expression in eukaryotes
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 18-1
Concept 18.1: Bacteria often respond to environmental change by regulating transcription
• Natural selection has favored bacteria that produce only the products needed by that cell
• A cell can regulate the production of enzymes by feedback inhibition or by gene regulation
• Gene expression in bacteria is controlled by the operon model
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 18-2
Precursor
Feedback
inhibition
trpE gene
Enzyme 1 trpD gene
Regulation of gene expression Enzyme 2
trpC gene
trpB gene
Enzyme 3 trpA gene
Tryptophan
(a) Regulation of enzyme activity (b) Regulation of enzyme production Operons: The Basic
Concept
• A cluster of functionally related genes can be under coordinated control by a single on-off
“switch”
• The regulatory “switch” is a segment of DNA called an operator usually positioned within the promoter
• An operon is the entire stretch of DNA that includes the operator, the promoter, and the genes that they control
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
• The operon can be switched off by a protein repressor • The repressor prevents gene transcription by binding to the operator and blocking RNA polymerase • The repressor is the
18
Regulation of Gene
Expression
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: Conducting the Genetic
Orchestra
• Prokaryotes and eukaryotes alter gene expression in response to their changing environment • In multicellular eukaryotes, gene expression regulates development and is responsible for differences in cell types
• RNA molecules play many roles in regulating gene expression in eukaryotes
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 18-1
Concept 18.1: Bacteria often respond to environmental change by regulating transcription
• Natural selection has favored bacteria that produce only the products needed by that cell
• A cell can regulate the production of enzymes by feedback inhibition or by gene regulation
• Gene expression in bacteria is controlled by the operon model
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 18-2
Precursor
Feedback
inhibition
trpE gene
Enzyme 1 trpD gene
Regulation of gene expression Enzyme 2
trpC gene
trpB gene
Enzyme 3 trpA gene
Tryptophan
(a) Regulation of enzyme activity (b) Regulation of enzyme production Operons: The Basic
Concept
• A cluster of functionally related genes can be under coordinated control by a single on-off
“switch”
• The regulatory “switch” is a segment of DNA called an operator usually positioned within the promoter
• An operon is the entire stretch of DNA that includes the operator, the promoter, and the genes that they control
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
• The operon can be switched off by a protein repressor • The repressor prevents gene transcription by binding to the operator and blocking RNA polymerase • The repressor is the