Molecular Genetics of Prokaryotes Problem Set
Problem 3: Phenotype of lac Z- E. coli cells
An E. coli strain is lac Z. The structural gene for ß-galactosidase is encoded at the lac Z locus. How would you describe the regulation of lactose metabolism in these cells?
A.
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normal regulation of lactose metabolism.
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B.
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constitutive expression of lac Z.
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C.
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inability to synthesize the lac Z- gene product, ß-galactosidase.
Cells mutated in the structural gene lac Z which encodes the enzyme ß-galactosidase cannot synthesize the enzyme.
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D.
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lac Z gene is inducible, but unable to be repressed by high glucose.
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E.
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no synthesis of the lac I gene product, the lac repressor.
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