北京大学：《微生物学》课程PPT教学课件（英文版）Chapter 7 Regulation of Gene Expression

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

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 Regulated Components of Metabolism DNA、X Transcription mRNA Tra anslation Protein (enzyme) Catalysis Regulation of enzyme activity Compound A Compound B

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

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

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

Example: Diauxic Growth Diauxic growth on mixture of glucose and lactose (The lac operon)

△ ttenuation Tryptophan Operon: Control systems do not involve regulatory proteins that bind to the DNA

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

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

Global Regulation Often an organism needs to regulate many different genes simultaneously in response to a change in its environment. – Catabolite repression

Ouestions 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

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?