Lesson 9 Gen. Reg of Gene expression in Prok.

Levels of gene expression regulation

DNA level

Transcriptional Level

• Transcriptional activators

• mRNA processing

• RNA stability
  Translational level

• Rate of translation

  Post translational

• Protein modification

Regulatory Genes

Genes whose products interact with DNA sequences and affect transcription or translation

Structural genes

Encodes proteins that are used in metabolism or biosynthesis and play a structural role

Regulatory elements

DNA sequences where the proteins produced by regulatory genes recognize and bind

Constitutive expression

Continously expressed uinder normal cellular conditions.

Positive control

Stimulates gene expression, activator

Negative control

Inhibits gene expression, repressor

Inducible

Normally structural genes are not transcribed

Repressible

Normally structural genes are transcribed

DNA Binding proteins

Regulator proteins that bind to DNA sequences and affect gene expression

Domain

60-90 AA and responsible for binding to DNA

Motif

Simple structure WITHIN binding domain

Bacterial genes with related functions are clustered together with

One single promoter and transcribed together into a single mRNA

Operon

A group of bacterial functional genes that are transcribed together.

Operon organization

promoter

Operator: DNA sequence is bound by regulatory protein to regulate transcription. Between promoter and structural genes

Structural genes: encodes the proteins

Types of negative control

Negative inducible

Negative repressible

Positive control types

Positive inducible

Positive repressible