Ion channels allow for the transport of a specific current, causing a the current readings from patch clamping experiments to have defined levels for the number of ion channels open. This is due to the maximum transport rate of the ion channels within the membrane - ion channels always transport at their maximum rate unless the concentration gradient is too low to allow maximal transport.
Having more ion channels open will result in the reduction of a transmembrane voltage, as the ion gradient is reduced when channels open. This is due to their passive transport nature, and therefore cannot move ions against the concentration gradient.
As all channels produce the same depth of deflection in the current graphs obtained from patch clamping, it is possible to say that they all (of the same class) provide the same rate of transport.
The opening and closing of ion channels is highly random. Even when they are not induced to open, occasional openings can be observed due to this random nature.
Voltage-gated Na+ and K+ channels, found in nerve cells, have a voltage-sensing subunit to control their opening. This charged subunit is able to detect the transmembrane potential, being pulled towards the more negatively charged side. Through a lever connecting domain, the conformation of the ion channel subunit can be changed to induce the opening of the channel. This allows the synchronous opening of ion channels in nerve cells, enabling the passage of an action potential along the entire axon of a nerve cell. An action potential is formed by depolarising the membrane potential, causing a change that can be detected by voltage-sensing subunits.