Now, for each region of the lac operon on the bacterial chromosome, ? P+ O+Z+ y

Question

Now, for each region of the lac operon on the bacterial chromosome, ? P+ O+Z+ y determine whether the region is wild type (that is, it produces a functional protein or it's a correct protein binding sequence) or whether the region is mutated. Select all that apply The promoter sequence is correct/functional The repressor protein is produced The operator sequence is correct/functional Beta-galactosidase is produced from the lacZ gene. Permease is produced from the lacY gene. Previous Answers Correct This lac operon, ? ?+ O+ Z+ Y, has a normal promoter sequence. Of the two structural genes (lacZ and lacY), only laaZ has a wild-type sequence. In terms of regulation in response to lactose, the operon does not produce any repressor protein (), however the operator sequence is wild type Part D Use the information from Part C to determine how the operon is regulated for this genotype (rpt o z Y) Operon is inducible; lacZ is transcribed only in the presence of lactose. Operon is constitutive; lacZ is transcribed even when lactose is absent. Operon is noninducible; lacZ is never transcribed, even in the presence of lactose. Operon is repressible; lacZ is only expressed in the absence of lactose

Explanation / Answer

Option B- lac operon is constitutive, LacZ is transcribed even in the absence of lactose.

LacI gene codes for lac repressor protein. Lac repressor binds to the operator sequence, preventing expression of lac operon genes in the absence of lactose. Lac repressor is constitutively bound to the lac operator and suppress lac operon expression. Lactose when present in the medium is taken up by the cell and converted to an inducer molecule, allolactose. Allolactose upon binding to lac repressor inactivates it, by preventing its binding to the operator region, leading to induction of lacZ expression. When LacI is mutated, as in I-P+O+Z+Y-, no lac repressor is produced. No lac repressor, so the constitutive expression of lacZ gene.

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