The lac repressor protein is bound to the operator region of the lac operon when there is no lactose in the medium. When introduced in lactose, it binds to an allosteric site on the repressor causing its to change conformation and release from the operator. This allows the polymerase that is bound to the promoter region to proceed transcription of the lac operon genes (LacZ, Lac A, and Lac Y). Translation of these genes forms enzymes that enable the organism to break down lactose for energy.
<span>Answer: Opening of Na+ and K+
Explanation:
Acetycholine binding opens Na+ and K+ ion channels in the receptors that allow simultaneous passage of Naâş into the muscle fiber and Kâş out of the muscle fiber. More Naâş ions enter than Kâş ions exit, which produces a local change in the membrane potential called the end plate potential.
Binding of acetycholine to receptor proteins opens Na+ and K+ channels resulting in jump in resting membrane potential(RMP) from -90mV to +75mV forming an end-plate potential (EPP).</span>
