Question

discuss the lac operon model of gene expression regulation

Answer 1

• the lac operon in e coli contains genes involved in lactose metabolism. it is expressed only when lactose is present and glucose is absent.

• two regulators turn the operon "on" and "off" in response to lactose and glucose level: the lac repressor and catabolite activator protein (CAP).

• The lac operon acts as a lactose sensor. it it normally blocks transcription of operon, but stops acting as a repressor when lactose is present. The Lac repressors senses the lactose indirectly, through its isomer allolactose.

• catabolite activator protein acts as a glucose sensor. it activates transcription of operon, but only when glucose levels are low. CAP senses glucose indirectly, through The "hunger signal" molecule cAMP.