You can determine the regulation of an unknown operon based on descriptions like those in the table below. For each row, choose whether the fact would suggest positive or negative or inducible or repressible regulation and indicate your answer with an X in the column. Only one X should appear in each row. In the presence of the signal, the structural genes are expressed. In the presence of the signal, the structural genes are not expressed. In the absence of the signal, the structural genes are expressed. In the absence of the signal, the structural genes are not expressed. The binding of the regulatory protein to the operon results in structural gene expression. The binding of the regulatory protein to the operon prevents structural gene expression. A mutation in the regulatory protein results in constitutive expression of the structural genes. A mutation in the regulatory protein results in no or low expression of the structural genes. Positive? Negative? Inducible? Repressible?

What is a specific region in the trp operon that you could mutate so it expresses the trp operon in conditions of excess tryptophan. Why will this mutation cause this? Operon structure: promoter, operater, structural genes promoter -  DNA region that is the site of RNA polymerase sigma binding and transcription initiation operator – DNA region that influences gene expression through its interaction with a protein (transcription factor) structural genes – gene whose expression is being regulated; encodes a polypeptide or functional RNA

In the regulation of the tryophan operon in bacteria, the co-occurence of transcription and translation plays a key role regulating full activation of operon expression. Diagram and explain how during the conditions of high tryptophan concentration this system regulates the expression of genes in the operon.

The lac operon is a negative inducible system and allolactose will bind to the regulator protein when present. Which of the following is true? the free repressor (not bound by the inducer) cannot bind to the operator. allolactose must bind to the lac repressor protein, preventing it from binding to DNA, in order for the structural genes to be transcribed. allolactose must be absent in order for the structural genes to be transcribed. the presence of allolactose prevents transcription of the the lacl gene, which encodes the lac repressor.

You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan.  Using your knowledge of operons and their regulation   a.Which operons would be functional under these conditions? b.What repressors would be made? (NOTE: name the repressors using their gene names) c.Which repressor(s) would be made in the inactive form? d.Which repressor(s) would be made in the active form? e.Which repressor(s) under these conditions can bind the operator sequence? f.Which repressor(s)under these conditions cannot bind the operator sequence?

To characterize the promoter of the gadA operon you made a series of deletion mutants removing pieces of the promoter to see what would happen. The results are found below: gad promoter gada gadX gadz 450 +1 lacz activity transcription start site pH 2.0 pH 7.0 A gad promoter beta-galactosidase (lacZ) +++ 450 gad promoter beta galactosidase (lacZ) +++ +++ 300 +1 gad promoter beta galactosidase (lacZ) 150 D gad beta galactosidase (lacz) -450 150 E gad promoter beta-galactosidase (lacZ) -450 -300 Based on these results, what can you conclude about the gad promoter? O a. The promoter is only regulated by repression Ob. The promoter is regulated by a mix of activation and repression O c. The promoter is only regulated by activation O d. The promoter has multiple operators and multiple enhancers

Suppose that  a  new  mutation  lacIes, ('es'  stands  for  ‘extra-strength’)  has been discovered in the  lac operon  that allows  the  lac-repressor  to bind even  to  the  lacOc  operator.  Other  properties of  lacIes repressor  remain  normal (that is the same  as  of  lacI+).  Given  this genotype    Is P+ Oc Z+ Y-  / Ies  P+  O+ Z+  Y+  ,  under  which conditions will the gene  lacZ  be  transcribed  to  produce  β-galactosidase and the gene  lacY  transcribed to  produce  permease?     A)  With  lactose,  β-galactosidase and permease are  produced, without  lactose they  are  not produced B)  With  lactose,  β-galactosidase is produced, without  lactose it is not;  permease is never produced C)  β-galactosidase is always produced  and  permease is never  produced D)  With  lactose,  β-galactosidase and permease are  produced, without  lactose they  are  also produced E)  β-galactosidase is always produced  and  permease is produced only  in the  presence of  lactose

A mutation at the operator prevents the regulator protein from binding.What effect will this mutation have in the following types of operons? Q. Regulator protein is a repressor of a repressible operon.

Molecular biology, please explain in detail