Question

I remember the professor telling the class LacZ and LacY both are not inducible. Maybe one of them is but not both. Please help explain.

For each of the E. coli strains containing the lac operon alleles listed, indicate whether the strain is inducible, constitutive, or unable to express ?-galactosidase and permease. Provide an explanation for your prediction

C. I+ O+ Z- Y+ / I? O^c Z+ Y?

Answer 1

Lac operon is the Kind of inducible operon while in absence of lactose , operator will be blocked with a   repressor protein, the operon is consist of promoter, operator three genes (lacZ, lacA, and lacZ) which make ?-galactosidase, permease, transacetylase, three of this genes are involved in the breakdown of the lactose molecule. ?-galactosidase breaks lactose glucose, galactose.

All lactose is an example of an inducer, a small molecule lac operon is inducible operon , usually turned off but can be turned on in the presence of the inducer allolactose.The need for lactose sugar source to the bacteria the 3 genes of lac operon are expressed and their proteins are translated lacZ, lacA and lacY. The gene product of lacZ is ?-galactosidase which break lactose into glucose and galactose sugar.

For sequence:

I+ O+ Z- Y+ ; Functional repressor is present(I) , y+is wild type while operator is wild type, the operon is constitutive type .the permease molecule is add when lactose is absent.

The beta-galactosidase is made from lacZ gene.
lac operon, I- OC+ Z+ Y lacZ has a wild-type sequence, regulation in response to lactose, the operon does not produce any repressor protein(I-)the operator is mutated.