Question

Which is not negatively controlled operon?

Answer 1

Answer:

Positive control: "catabolite repression"

Explanation:

1. Catabolite repression

a. Even bacteria can be picky about what they eat. Glucose is the preferred source of carbon for E. coli; the bacterium will consume the available glucose before utilizing alternative carbon sources, such as lactose or amino acids.

b. Glucose leads to repression of expression of lacand some other catabolic operons. This phenomenon is called catabolite repression.

2. Two components are needed for this form of regulation

a. cAMP

[1]In the presence of glucose, the [cAMP] inside the cell decreases from 10-4 M to 10-7 M. A high [cAMP] will relieve catabolite repression.

[2]cAMP synthesis is catalyzed by adenylate cyclase (product of the cyagene)

Answer 2

hey mate : )

=============================

Glucose present, lactose absent: No transcription of the lac operon occurs. That's because the lac repressor remains bound to the operator and prevents transcription by RNA polymerase. Also, cAMP levels are low because glucose levels are high, so CAP is inactive and cannot bind DNA.

============================

hope it helps ^_^