Question

A) Given the following genotypes of E. coli strains, predict whether the lacZ gene will be inducibly expressed, constitutively expressed, or permanently repressed in the presence of lactose as the only sugar.

Genotype                   

I+O+Z+  will have the lacZ gene __________ ,  because  __________

I-O+Z+   will have the lacZ gene  __________ ,  because __________   

I^SO+Z+   will have the lacZ gene __________ ,  because  __________​     

I+O^CZ+   will have the lacZ gene  __________ ,  because __________​             

I^SO^CZ+ will have the lacZ gene  __________ ,  because  __________    

Answer 1

Answer

In the presence of lactose, the lac Z gene expression will be the following

I+O+Z+  will have the lacZ gene inducibly expressed because all the cis and trans elements are active

I-O+Z+   will have the lacZ gene constitutively expressed because repressor protein does will not express

I^SO+Z+   will have the lacZ gene, permanently repressed because of the super suppressor will express and it binds to the operator.       

I+O^CZ+   will have the lacZ gene  constitutively expressed because the operator is mutated which does not bind with repressor   

I^SO^CZ+ will have the lacZ gene constitutively expressed, because of the operator is mutated which does not allow super-repressor to bind with