In the lactose operon of E. coli, which of the following genotypes produces functional $\beta$-galactosidase constitutively?

Question

Quizplus · Accepted Answer

The lac operon consists of three structural genes, lacZ, lacY, and lacA, involved in lactose metabolism, along with a promoter (P), an operator (O), and a regulatory gene (lacI). The genotype I^- represents a mutation in the operator region that prevents the binding of the Lac repressor protein, resulting in the constitutive expression of the operon. The genotypes P⁺ and O⁺ represent mutations in the promoter region that increase or decrease the expression of the operon, respectively. The genotype Z⁺ represents a mutation in the lacZ gene, which encodes β-galactosidase, and can result in a non-functional or partially functional enzyme. The genotype Y^- represents a mutation in the lacY gene, which encodes lactose permease, and can result in a non-functional or partially functional protein. Therefore, only genotype D, I^- P⁺ O⁺ Z⁺ Y^-, includes a functional lacZ gene and a mutation in the operator that allows for constitutive expression of the operon, producing functional β-galactosidase at all times.

In the Lactose Operon of E β\betaβ -Galactosidase Constitutively? A)I+ P+ O+ Z- Y+ B)I+ P+ O+

In the Lactose Operon of E $\beta$ -Galactosidase Constitutively?
A)I⁺ P⁺ O⁺ Z^- Y⁺
B)I⁺ P⁺ O⁺