The table below lists several genotypes associated with the lac operon in E. coli. For each, indicate with a "+" or a "-" whether ?-galactosidase would be expected to be produced at induced levels
?-Galactosidase Production
Genotype No Lactose With Lactose
(a) I + O+ Z+/F' I - O+ Z+
(b) I - Oc Z -/F' I - Oc Z -
(c) I - Oc Z+/F' I - O+ Z+
(d) I s Oc Z -/F' I s O+ Z+
I + = wild-type repressor
I - = mutant repressor (unable to bind to the operator)
I s = mutant repressor (insensitive to lactose)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
(a) - +
(b) - -
(c) + +
(d) - -
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