The Trp Operon

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What is the trp operon? - The trp operon was first discovered by Jacques Monod and his colleagues in1953. It is the operon, set of DNA in the genome which has a group of genes controlled by an operator, used in the production of tryptophan. Trptophan's molecular formula is C11H12N2O2. The trp operon is a repressor operon. A repressor is a protein molecule which attaches to DNA to regulate the expression of genes. It does this by decreasing the level of transcription taking place. The operon is said to be around 6756 base pairs long. The trp operon was originally found in Escherichia Coli, E.Coli. E.Coli can acquire tryptophan either by producing it itself or by extracting it from what the cell is consuming. This is the chemical structure …show more content…
- The trp operon is necessary for the synthesis of tryptophan when it is not already available from the environment. When this occurs transcription is started by the switch controlling the trp operon, the genes are expressed and trptophan is …show more content…
Domain 4 is called 'the attenuator' due to it's presence being needed to reduce mRNA transcription when surrounded by high levels of tryptophan.
How does the trp operon work? – Five genes are necessary to produce tryptophan in E. coli. They are all beside one another in the operon. They are trp E, trp D, trp C, trp B and trp A. Tryptophan being present in large quantities results in the repressor protein being attached to the operator sequence by two tryptophan molecules. The RNA polymerase is then unable to transcribe the tryptophan genes. When tryptophan is not present the genes can be transcribed. This is due to the repressor protein not attaching to the operator.
The trp operon is a repressible system. Repressible and inducible systems have very different outcomes when the effector molecule attaches to the repressor. The force at which the repressor attaches to the operator increases greatly in repressible systems when the effector molecule binds to the repressor, and the repressor binds to the operator and blocks transcription. Looking at the trp operon, when tryptophan, which is the effector molecule, is added to the E.coli environment the system is terminated because the repressor binds at the
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