Will β-galactosidase be produced under the circumstances: 1) first in the absence of lactose and 2) second in the presence of lactose?
Will β-galactosidase be produced under the circumstances: 1) first in the absence of lactose and 2) second in the presence of lactose?
The following shows the genotype of a partial diploid bacterial cell - where one chromosomal region containing the lac operon in E,coli is given, and the other fragment is from a plasmid carrying another lac operon from another source. The two are separated by a slash (/). The possible answers indicate with a ʺ+ʺ or a ʺ-ʺ whether β-galactosidase would be expected to be produced at induced levels under two circumstances: 1) first in the absence of lactose and 2) second in the presence of lactose. (Assume that glucose is not present in the medium.)
Genotype A: I + O+ Z+/ Fʹ I - O+ Z+
Genotype B: I - Oc Z+/ Fʹ I - O+ Z-
Genotype C: Is Oc Z+/ Fʹ I + O+ Z+
Genotype D: I- O+ Z+/ Fʹ I- O+ Z+
Genotype E: I + O+ Z+/ Fʹ I + O+ Z+
Genotype F: I- Oc Z-/ Fʹ I- Oc Z-
Genotype G: I- Oc Z+/ Fʹ I- O+ Z+
Genotype H: Is Oc Z-/ Fʹ Is O+ Z+
Possible Answers:
a.) (+,+)
b.) (- , -)
c.) (+, -)
d.) (-, +)
e.) Cannot Tell
KEY:
I+ = wild-type repressor
I- = mutant repressor (unable to bind to the operator)
Is = mutant repressor (insensitive to lactose)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
No Answers Posted Yet.