Question

Poisons like cyanide inhibit $N{a}^{+}$ efflux and $K^{+}$ influx during cellular transport. This inhibitory effect is reversed by an injection of ATP. This demonstrates that

• A. ATP is the carrier protein in the transport system
• B. $N{a}^{+}$ - $K^{+}$ exchange pump operates in the cell
• C. ATP is hydrolyzed by ATPase to release energy
• D. Energy for $N{a}^{+}$ - $K^{+}$ exchange pump comes from ATP

Answer 1

Answer: (D)

Energy for $N{a}^{+}$ - $K^{+}$ exchange pump comes from ATP

Cyanide is known to be a toxic chemical compound, as it binds to the fourth complex called the cytochrome c oxidase of the electron transport chain, and inhibit its usual action. Cyanide binds to the iron present in the protein complex and inhibits the transport of electrons to oxygen. As a result, the ATP production also halts, and the passage of electrons are blocked all through the electron transport chain. Cyanide halts the Na+ efflux and K+ influx during cellular transport since the protons are not allowed to return back into the mitochondrial matrix. This inhibitory effect is reversed when ATP is injected which provides consequent energy to the Na+-K+ exchange pump. This demonstrates that Na+-K+ exchange pump gets energy from ATP.

So the correct answer is 'Energy for Na${}^{+}$ - K${}^{+}$ exchange pump comes from ATP'

Na+