Final answer:
The specificity of K channels for K or Na is mainly the result of the gating mechanism of the channel. The voltage-gated K+ channel opens and closes at specific membrane potentials, allowing the selective movement of potassium ions (K+) across the cell membrane.
Step-by-step explanation:
The specificity of K channels for K or Na is mainly the result of the gating mechanism of the channel. Specifically, the voltage-gated K+ channel has one gate that is sensitive to a membrane voltage of -50 mV. It opens and closes at specific membrane potentials, allowing the selective movement of potassium ions (K+) across the cell membrane. The timing of the K+ channel opening coincides with the inactivation of the voltage-gated Na+ channels, ensuring sequential ion movement during action potentials.