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Predict the phenotype of a lac Y mutant, which is a mutation in the gene for...

Predict the phenotype of a lac Y mutant, which is a mutation in the gene for lactose permease.

a. The lac genes would be expressed efficiently only in the absence of lactose.

b. The lac genes would be expressed efficiently until the lactose supply already in the cell is exhausted.

c. The lac genes would be expressed continuously.

d. Expression of the lac genes would cease immediately.

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Answer #1

The correct answer is:

b. The lac genes would be expressed efficiently until the lactose supply already in the cell is exhausted.

Lactose cannot enter cell if there is no lactose permease as because the lactose permease is involved with the transport of lactose into the cell through the cell membrane

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