The Table Below Lists Several Genotypes Associated with the Lac $\beta$

question 56

Essay

The table below lists several genotypes associated with the lac operon in E.coli.For each,indicate with a "+" or a "-" whether functional $\beta$ -galactosidase would be expected to be produced at induced levels.
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\text { B-Galactosidase Production }$
$\begin{array}{lccc}\text { Genotype }& \text { No Lactose } &\text { With Lactose } \\\hline \text { (a) } I+O+Z+/ F^{\prime} I-O+Z+\\\text { (b) } I-O c Z+/ F^{\prime} I-O+Z-\\\text { (c) Is Oc Z+/ } F^{\prime} I+O+Z+\\\text { (d) } I-O+Z+/ F^{\prime} I-O+Z+\\\end{array}$

$I^{+}=$ wild-type repressor
$I$ - = mutant repressor (unable to bind to the operator)
$\mathrm{I}^{s}=$ mutant repressor (insensitive to lactose)
$\mathrm{O}^{+}=$ wild-type operator
$\mathrm{O}^{c}=$ constitutive operator (insensitive to repressor)

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