Chapter 7 Regulation of Gene Expression
?Regulation of Enzyme Activity
– Constitutive enzymes
– Enzymes induced by specific circumstances
?Two major modes of regulation in the cell
– Control the activity of preexisting enzymes
– Control the amount of an enzyme
Regulation can be performed in gene expression and
enzyme activity level
Inhibition Types
?Feedback inhibition
– the activity of the first enzyme of the pathway
is inhibited by the end product.
?Covalent modification
– The activity of an enzyme is affected by
? attachment of the nucleotide adenosine mono-
phosphate (AMP) or adenosine diphosphate (ADP)
? attachment of inorganic phosphate
? methylation
Regulation of Transcription
?Regulation of transcription,regulation of
enzyme synthesis:
– Induction,the synthesis of an enzyme only
when its substrate is present
– Repression,no enzyme synthesis in the
presence of its product
?Example; The lac operon
Example,Diauxic Growth
?Diauxic growth on mixture of glucose and
lactose (The lac operon)
Attenuation
?Tryptophan Operon,Control systems do not
involve regulatory proteins that bind to the
DNA
Signal Transduction and Two-
Component Regulatory Systems
?Signal transduction,A signal is first
detected by a sensor and then transmitted in
a changed form to the rest of the regulatory
machinery.
?Two-component systems,
– a specific sensor protein located in the cell
membrane
– a partner response regulator protein
Global Regulation
?Often an organism needs to regulate many
different genes simultaneously in response
to a change in its environment.
– Catabolite repression
Questions
? How is gene expression regulated?
? How do induction and repression work to regulate microbial
metabolism
? Describe positive and negative control in transcription level of
regulation
? How does lac operon work to regulate lactose metabolism
? Give an example of attenuation
? Give an example of global control in cell metabolism
? What are signal transduction and two-component regulatory system?
? Describe the difference of gene expression between prokaryotes and
eukaryotes
? What is antisense RNA and its applications?
?Regulation of Enzyme Activity
– Constitutive enzymes
– Enzymes induced by specific circumstances
?Two major modes of regulation in the cell
– Control the activity of preexisting enzymes
– Control the amount of an enzyme
Regulation can be performed in gene expression and
enzyme activity level
Inhibition Types
?Feedback inhibition
– the activity of the first enzyme of the pathway
is inhibited by the end product.
?Covalent modification
– The activity of an enzyme is affected by
? attachment of the nucleotide adenosine mono-
phosphate (AMP) or adenosine diphosphate (ADP)
? attachment of inorganic phosphate
? methylation
Regulation of Transcription
?Regulation of transcription,regulation of
enzyme synthesis:
– Induction,the synthesis of an enzyme only
when its substrate is present
– Repression,no enzyme synthesis in the
presence of its product
?Example; The lac operon
Example,Diauxic Growth
?Diauxic growth on mixture of glucose and
lactose (The lac operon)
Attenuation
?Tryptophan Operon,Control systems do not
involve regulatory proteins that bind to the
DNA
Signal Transduction and Two-
Component Regulatory Systems
?Signal transduction,A signal is first
detected by a sensor and then transmitted in
a changed form to the rest of the regulatory
machinery.
?Two-component systems,
– a specific sensor protein located in the cell
membrane
– a partner response regulator protein
Global Regulation
?Often an organism needs to regulate many
different genes simultaneously in response
to a change in its environment.
– Catabolite repression
Questions
? How is gene expression regulated?
? How do induction and repression work to regulate microbial
metabolism
? Describe positive and negative control in transcription level of
regulation
? How does lac operon work to regulate lactose metabolism
? Give an example of attenuation
? Give an example of global control in cell metabolism
? What are signal transduction and two-component regulatory system?
? Describe the difference of gene expression between prokaryotes and
eukaryotes
? What is antisense RNA and its applications?
