In: Biology
You are growing E. coli in a laboratory. The growth media you are using contains lactose, no glucose and no tryptophan. On a separate sheet of paper - diagram what specific operons would be induced and functional under these conditions. In your drawing:
a. Show how the operon(s) would be regulated using the conditions given above.
b. Be sure to include all regulatory genes, repressors, co-repressors, inducers etc….
c. If transcription & translation is possible, indicate this in your drawing by showing what genes would be expressed.
Your drawing of the operon(s) will be worth 4 points
Use your drawing to answer the following questions (9 points):
On your drawing - answer these questions
10. Explain your answer for question #7
11. Explain your answer for question #8
12. Explain your answer for question #9
1- Lac and Trp
2- No repressor
3- TrpR and LacI
4- No repressor
5- No repressor
6- TrpR and LacI
7- It induces the operon
8- It accelerated the Lac operon
9- the Trp operon is inhibited
10- Allosteric
10th Ans- when lactose enters the cells it gets converted to allolactose which binds to the repressor. since the repressor does not bind to the operator RNA polymerase is allowed to transcribe the gene to mRNA.
11th Ans- when glucose is absent in the medium, cAMP level increases in the cell which activate CAP(class 1 activator) which binds to 22bp sequence on gene that helps RNA pol to move and hence accelerates the lac operon
12th Ans- Trp is a co-repressor that activates TrpR. Activated TrpR binds to the operator and hence the RNA pol is not allowed to move ahead,this leads to the inactivation of Trp operon