Unit 2 Cell Transport

cell membrane function

Controls what enters and leaves the cell

Homeostasis

process by which organisms maintain a relatively stable internal environment

selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

phospholipid bilayer

Plasma membrane layers composed of phospholipid molecules arranged with hydrophilic heads facing the outside and hydrophobic tails facing the inside.

Hydrophilic

water loving

Hydrophobic

Water fearing

concentration gradient

difference in the concentration of a substance from one location to another

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

osmosis

Diffusion of water through a selectively permeable membrane

passive transport

Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient