Final answer:
K+ channels permit the selective passage of potassium ions (K+) and prefer these ions over sodium ions (Na+) due to size exclusion. Human DNA encodes for dozens of different K+ channels, allowing a varied array of functions in physiological processes.
Step-by-step explanation:
K+ channels are specific types of ion channels that allow the passage of potassium ions (K+) through their pores. They are highly selective and prefer K+ over Na+ largely because of the size exclusion mechanism, where the pore size is tailored to match the size of K+ ions when they shed their hydration shell. This selectivity is crucial for maintaining the cell's electrochemical gradient.
In the human body, the K+ channels play a key role in various physiological processes, such as setting the resting membrane potential and shaping action potentials in nerve and muscle tissue. Humans possess a diverse array of K+ channel types encoded by various genes. Although an exact number is difficult to state due to the presence of splice variants and subunit combinations, it is estimated that human DNA encodes for dozens of different K+ channel subunits, which can combine to create a large diversity of channel conformations.