Question

What are examples of positive and negative control of the lac operon? Answer 1. Lactase, which breaks down lactose, is an example of positive control, and cAMP, which binds to CRP, is an example of negative control. 2. cAMP, which binds to CRP, is an example of positive control, and lactase, which breaks down lactose, is an example of negative control. 3. Lactase, which breaks down lactose, is an example of positive control, and glucose, which reduces cAMP, is an example of negative control. 4. Glucose, which reduces cAMP, is an example of positive control, and lactase, which breaks down lactose, is an example of negative control.

Answer 1

4. Glucose, which reduces cAMP, is an example of positive control, and lactase, which breaks down lactose, is an example of negative control.

Step-by-step explanation:

During positive control, the presence of Glucose results in the repression of expression of lac operon. This concept is known as catabolite repression. During negative control, the lac genes are switched off by repressor when the inducer is absent (indicating the unavailability of lactose). But when lactose is present, lac binds the repressor protein and modifies it in order to dissociate it from the operator. The removal of the combination of repressor and inducer helps lac to be transcribed and expressed.