Which of these haploid strains produces β- galactosidase constitutively but does not produce permease?
A) I+ P+ O- Z+ Y+
B) I- P+ O+ Z+ Y-
C) I - P+ O+ Z+ Y+
D) I+ P+ O+ Z- Y-
E) I- P+ O+ Z- Y+

Question

Quizplus · Accepted Answer

The strain described as I- P+ O+ Z+ Y- will produce β-galactosidase constitutively because the I- mutation means the lac repressor cannot bind and inhibit the lac operon, leading to constant expression of β-galactosidase (Z+). However, it does not produce permease because the Y gene, responsible for permease production, has a negative mutation (Y-), preventing its expression.

Which of These Haploid Strains Produces β- Galactosidase Constitutively but Does