18.1 An Overview of Gene Regulation and Information Flow

The flow of information from DNA to active protein suggest three possible mechanisms:
- Transcriptional control: The cell could make mRNAs only for proteins it needs.
- Translational control: The cell could prevent the mRNAs for unneeded proteins from being translated.
- Post-translational control: After translation, many proteins have to be activated by chemical modification, such as the addition of a phosphate group, in order to function.
An inducer is a small molecule that triggers transcription of a specific gene.

18.2 Negative and Positive Control of Transcription

Negative control occurs when a regulatory protein called a repressor binds to DNA and shuts down transcription
Positive control occurs when a regulatory protein called an activator binds to DNA and triggers transcription
Cells that are abnormal because they produce a product at all times instead of regulating expression of the product are called constitutive mutants.
Jacob and Monod coined the term operon to describe a set of coordinately regulated bacterial genes that are transcribed together into one polycistronic mRNA.
The group of genes involved in lactose metabolism was termed the lαc operon.
The repressor binds to a DNA sequence in the lαc operon called the operator.
In allosteric regulation, a small molecule binds to a protein and causes it to change its shape and activity.
A protein known as the catabolite activator protein (CAP) has long been viewed as exerting positive control of many operons in E. coli, including the lαc operon.
Negative feedback control is a form of control in which the final product of a pathway inhibits the production of the product.
The only difference is that for the trp operon the small molecule regulator is called a co-repressor, because it works with the repressor to make it active.

Global gene regulation is the coordinated regulation of many genes.
Regulon is a set of separate genes and operons at contain the same regulatory sequences and are controlled by a single type of regulatory protein
A key part of the regulatory logic of the SOS system is that it is under the control of one of its own genes.

The flow of information from DNA to active protein suggest three possible mechanisms:
- Transcriptional control: The cell could make mRNAs only for proteins it needs.
- Translational control: The cell could prevent the mRNAs for unneeded proteins from being translated.
- Post-translational control: After translation, many proteins have to be activated by chemical modification, such as the addition of a phosphate group, in order to function.
An inducer is a small molecule that triggers transcription of a specific gene.

Negative control occurs when a regulatory protein called a repressor binds to DNA and shuts down transcription
Positive control occurs when a regulatory protein called an activator binds to DNA and triggers transcription
Cells that are abnormal because they produce a product at all times instead of regulating expression of the product are called constitutive mutants.
Jacob and Monod coined the term operon to describe a set of coordinately regulated bacterial genes that are transcribed together into one polycistronic mRNA.
The group of genes involved in lactose metabolism was termed the lαc operon.
The repressor binds to a DNA sequence in the lαc operon called the operator.
In allosteric regulation, a small molecule binds to a protein and causes it to change its shape and activity.
A protein known as the catabolite activator protein (CAP) has long been viewed as exerting positive control of many operons in E. coli, including the lαc operon.
Negative feedback control is a form of control in which the final product of a pathway inhibits the production of the product.
The only difference is that for the trp operon the small molecule regulator is called a co-repressor, because it works with the repressor to make it active.

Global gene regulation is the coordinated regulation of many genes.
Regulon is a set of separate genes and operons at contain the same regulatory sequences and are controlled by a single type of regulatory protein
A key part of the regulatory logic of the SOS system is that it is under the control of one of its own genes.