Question

When glucose is present, enzyme IIAglc is __________ and LacY is __________. a. phosphorylated; inhibited b. not phosphorylated; inhibited c. phosphorylated; activated d. not phosphorylated; activated

Answer 1

Option B, not phosphorylated; inhibited

Step-by-step explanation:

Glucose 6 acts as a catobolite repressant . A catobolite repressant which is usually a carbon compound inhibits the operon transcription. In the presence of glucose -6, unphosphorylated enzyme IIAGlc inhibits the transportation system and hence prevents the utilization of lactose. Glucose‐6‐phosphate and other non‐PTS carbon causes inducer exclusion thereby leading to dephosphorylation of enzyme IIAGl without getting transported.

Hence, option B is correct