Passive Transport
The transport of molecules across a cell membrane by diffusion.
Active Transport
A process that moves chemicals across a cell membrane against a concentration gradient, using energy (ATP).
Diffusion
The process by which molecules of gas or liquid move from an area of high concentration to an area of lower concentration.
Osmosis
Movement of water across a partially permiable membrane from dilute solution to a more concentrated one (without energy)
Facilitated Diffusion
Movement of specific molecules across cell membranes through protein channels
Vesicles
Membrane-bound compartments in eukaryotic cells.
Endocytosis
Cellular uptake of biological molecules via the formation of vesicles from the plasma membrane surrounding the molecule.
Exocytosis
A process in which a vesicle inside a cell fuses with the plasma membrane releasing its contents to the external environment.
Sodium-potassium pump
A carrier protein in membranes that uses ATP to do active transport of sodium ions out of a cell and potassium ions into the cell.
Potassium channel
A carrier protein in membranes which allows potassium to move out of a cell by facillitated diffusion.
Osmolarity
A measure of the concentration of solute particles (which cause osmosis) in a given volume of fluid.
Hypotonic
A solution whose solute concentration is lower than the solute concentration of another solution
Hypertonic
A solution whose solute concentration is higher than the solute concentration of another solution
Kidney dialysis
A process in which a machine uses osmosis and diffusion to filter urea salts and water from blood, in place of the kidneys.
Diffusion gradient
The difference in molecular concentration (the difference in concentrations) that allows diffusion to occur.