As a result, per capita income in Northwest Arkansas has converged with the national average. As of 2012, income per capita in Northwest Arkansas was about $36,000, about $6,000 below the national average. After adjusting for the lower cost of living in the region, per capita income in Northwest Arkansas was at that time, in effect, $40,000, just $2,000 shy of the national average.
Protein channels are important to facilitate the transport of ions and other larger molecules across the plasma membrane.   Large molecules cannot just diffuse thorough the â¦ membrane. In addition, polar molecules cannot diffuse through the membrane since it would be energetically unfavorable for them to negotiate the hydrophobic interior of the plasma membrane. Therefore, protein channels are essential in membrane transport.
Because ions are charged and water-soluble, they must move through small tunnels or channels (specialized proteins) that span the cell membrane's lipid bilayer. Each channel is specific for only one type of ion. There are specific channels for sodium ions, potassium ions, calcium ions and chloride ions. These channels make the cell membrane selectively permeable to various ions and other substances (like glucose).