In Order to Analyze How Different Components of the Lac

question 75

Multiple Choice

In order to analyze how different components of the lac operon work, scientists created special strains of E. coli, called partial diploids. A partial diploid has one full copy of the lac operon in the bacterial chromosome plus another copy of the lac operon in a plasmid. Hence, for the lac operon (and only the lac operon) the bacterial cell is a diploid. Below is one possible genotype of a partial diploid. The genotype written to the left of the slash (/) is that of the lac operon in the bacterial chromosome, and the genotype written to the right of the slash is that of the lac operon in the plasmid. I⁺ P^- O⁺ Z⁺/ I^- P⁺ O⁺ Z^-
For the partial diploid genotype shown here, determine whether functional -galactosidase is synthesized in the absence and in the presence of lactose (and the accompanying allolactose that is the actual inducer) .

• A)  -galactosidase is produced whether lactose is present or absent.
• B)  -galactosidase is not produced whether lactose is present or absent.
• C)  -galactosidase is produced when lactose is present but is not produced when lactose is absent.
• D)  -galactosidase is not produced when lactose is present but is produced when lactose is absent.

---

Definitions:

2-point Threshold

The minimum distance at which two points of contact can be felt as separate on the skin, a measure of tactile sensitivity.

Tactile Localization

The ability to determine the location on the body where a tactile stimulus has been applied.

Tactile Localization

The ability to determine which area of the skin has been touched, without visual cues.

Touch Receptors

Sensory receptors in the skin that detect tactile stimuli, enabling the sensation of touch, pressure, and vibration.