8.1 Cellular Transport
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
The diffusion of water across a selectively permeable membrane is called osmosis.
The diffusion of water across a selectively permeable membrane is called osmosis.
Some molecules can pass through the plasma membrane by diffusion. When the cell does not use energy to move these particles across the membrane it is classified as passive transport. Passive transport of materials across the membrane using transport proteins is called facilitated diffusion. Movement of materials through a membrane against a concentration gradient is called active transport and requires energy from the cell. Endocytosis {Endo (within) cytosis (cell) } is a process in which a substance gains entry into a cell without passing through the cell membrane.