3.11 - The Operon Flashcards
1
Q
What is an operon?
A
- It’s a set of genes.
- They are the system for controlling genes that regulats which genes can be switched on and off, depending of the cell’s needs.
- found between the genes and the promoter
- repressors binds to the operator to inhibit transcription
2
Q
What ar two examples of operons?
Where do they exsist?
A
LAC operon & TRP operon
They exsist ONLY within bacteria
3
Q
Briefly describe the LAC operon.
think lactose
A
- controls the genes that produce proteins required to digest lactose
- when no lactose is present, the genes shut off
- a repressor molecule blocks the promoter region so the genes can’t be transcribed.
- when lactose is present, it unblocks the promotor region by pulling the repressor of the DNA, expossing it and activationg the gene.
- when all the lactose has been digested, the repressor rebinds to the promotor, turning the gene off again
4
Q
Briefly describe the TRP operon.
think tryptophan (sleppy chemical in turkey meat)
A
- controls the genes that produces proteins needed to manufacture tryptophan
- this gene is normally left on and only need to be turned off when there is enough/ too much
- when there is too much, the tryptophan molecule itself binds to a repressor & forces it to bind to the promoter region to turn it off
- When tryptophan levels go low again, the repressor detatches, and the gene will be re-activated
5
Q
What do both LAC and TRP operons have in common?
A
- both are examples of negative control
- they use repressor proteins to hinder RNA polymerase activity
