DNA Replication RNA Protein TranscriptionTranslation
Bacterial growth on sugars How does the cell know which enzymes to express?
hours [conc.] glucose lactose Bacterial growth on two substrates: Two things to notice: 1.Glucose metabolized before lactose 2.Lag between glucose and lactose growth phases [Monod, Thesis 1942]
Monod realized this was operating like a genetic “switch” –Genes required for lactose metabolism turned off in presence of glucose –But turned on in absence of glucose and presence of lactose Input/Ouput relation:Lactose +- Glucose +-- -+-
crp lacI lacZ lacYlacA Three main components: 1.Genes: encode protein sequence 2.Promoters: RNAP binding sites 3.Operators: Transcription factor binding sites lacZ The lac Operon
The Prokaryotic Promoter NNNNTTGACANNNNNNNNNNNNNNNNNTATAATNNN -35-10 17 bp The promoter is a binding site for the protein RNA polymerase, responsible for transcription
DNA Replication RNA Protein TranscriptionTranslation Transcription factor (protein that repress or activate) Rate usually depends on transcription factor
Gene regulation functions ( rate of transcription as a function of factors or regulators)
Domain of bistability For both genes: maximal expression level should be able to repress the repressor HW: Sketch the phase planes for the 4 different regimes in the model Expression of both R 1 off
Your consent to our cookies if you continue to use this website.