a) when lactose is absent, the repressor is active, RNA Polymerase cannot bind to the promoter and the structural gene are not formed.
b) when lactose is present, the lac repressor is inactive, RNA Polymerase can bind to the promotor and the structural genes are formed.
Explanation:
The lac operon in E.coli has genes required for lactose metabolism.
It is expressed only when lactose is present in the medium and glucose is absent.
According to the glucose and lactose level the operon is switched on or off.
The lac repressor or allolactose and catabolite activator protein is present in lac operon.
Glucose is the primary source of energy but bacteria loves to fuel down lactose. To use lactose as an energy source lac operon works.
a) when lactose is absent, the repressor is active, RNA Polymerase cannot bind to the promoter and the structural gene are not formed.
b) when lactose is present, the lac repressor is inactive, RNA Polymerase can bind to the promotor and the structural genes are formed.
The lac repressor is a protein that inhibits transcription of lac operon in the absence of lactose.
Answer:
Nitrogen fixing bacteria
Explanation:
Nitrogen-fixing bacteria are the microbial organisms that play an important role in the conversion of atmospheric nitrogen gas into reactive nitrogen such as ammonia, nitrogen oxide, and nitrous oxide. These types of bacterias are comprised of an enzyme known as the 'nitrogenase enzyme' that allows the nitrogen gas to mix with hydrogen and eventually produces ammonia.
This ammonia is then concentrated in the soil and is later taken up by the plants which are highly essential for them as they ammonia are their main source of nitrogen. This helps in the growth, development, and expansion of the overall plant body.
