The rate of passive transport depends on the permeability of the cell membrane, which, in turn, depends on the organization and characteristics of the membrane lipids and proteins. The four main kinds of passive transport are diffusion, facilitated diffusion, filtration and osmosis.
DEFINITION of 'Privately Owned'. A company that is not publicly traded on a securities exchange. The majority of companies are privately owned, usually by either one individual or by a small group of individuals. Although offering securities for sale to the public can be a good way to obtain large amounts of financing, public ownership requires considerable effort to ensure compliance with securities regulations.
Many of the largest private companies today have been owned by the same families for multiple generations. Staying private means the company does not have to answer to its shareholders or choose different members for the board of directors. Some family-owned companies have gone public, and many maintain family ownership and control through a dual-class share structure, meaning family-owned shares have more voting rights. Going public is a final step for private