Induction (genetics)
In genetics and biotechnology, induction is the activation of a repressible promoter by an inducer . The promoter- controlled gene product is then produced, e.g. B. a protein (including enzymes ) or a microRNA . Chemical substances such as sugar , heavy metals , oxygen, etc. can occur as inductors , but induction via physical parameters such as temperature or light is also possible.
Lac operon
A classic example is the enzyme induction for lactose degradation in the lac operon , where the repressor molecule normally binds to the promoter of the lac operon and this binding is broken after the addition of lactose to the medium. The release of the repressor is regulated allosterically in that the inducer - in this case allolactose, a modified form of lactose - binds to the repressor and thus causes a steric change in the conformation of the repressor. This change in conformation has the consequence that the repressor can no longer bind to the promoter, it dissociates and thus enables the DNA-dependent RNA polymerase to transcribe the structural genes of the lac operon . These code for three proteins: a transport protein and two enzymes, one of which can split the disaccharide milk sugar into glucose and galactose .
See also
literature
- Reinhard Renneberg : Biotechnology for beginners. 3. Edition. Spektrum Akademischer-Verlag, Heidelberg 2010 edition, ISBN 978-3-8274-2045-9 .
- Lubert Stryer: Biochemie, Spektrum, Heidelberg - Berlin - Oxford 1996 (4th edition), p. 995ff