The expression of the lac structural genes is _______ when lactose is absent from the culture medium and is _______ when lactose is added because lactose binds to the _______ and inactivates it.

A: low; high; lac operator
B: high; low; lac operator
C: low; high; lac promoter
D: low; high; lac repressor
E: high; low; lac inducer


Answer: D: low; high; lac repressor

Biology & Microbiology

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Indicate whether this statement is true or false

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The sternum is a major site of red blood cell

formation. The bones in the sternum must be ___ bones.

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