Bacterial strategies to evade natural or human-imposed antibiotics are varied an

Question

Bacterial strategies to evade natural or human-imposed antibiotics are varied and include membrane-bound efflux pumps that export antibiotics from the cell.

A review of efflux pumps (Grkovic, S., et al., 2002) states that, because energy is required to drive the pumps, activating them in the absence of the antibiotic has a selective disadvantage. The review also states that a given antibiotic may play a role in the regulation of efflux by interacting with either an activator protein or a repressor protein, depending on the system involved.

1. In a negative inducible system, the presence of antibiotic

A.Promotes the binding of an activator molecule, allowing transcription

B.Promotes the binding of a repressor molecule, inhibiting transcription

C.Interrupts the binding of a repressor molecule, allowing transcription

D.Interrupts the binding of an activator molecule, inhibiting transcription

2. In a positive inducible system, the presence of antibiotic

A.Promotes the binding of an activator molecule, allowing transcription

B.Promotes the binding of a repressor molecule, inhibiting transcription

C.Interrupts the binding of a repressor molecule, allowing transcription

D.Interrupts the binding of an activator molecule, inhibiting transcription

Explanation / Answer

1. In a negative inducible system, the presence of antibiotic:

D.Interrupts the binding of an activator molecule, inhibiting transcription

2. In a positive inducible system, the presence of antibiotic:

A.Promotes the binding of an activator molecule, allowing transcription

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