Chapter 3B: Passive Transport

passive transport

the movement of materials across the plasma membrane, down a concentration gradient, that does not require energy

diffusion

passive transport of molecules down a concentration gradient (area of high concentration to low concentration)

concentration gradient

difference in solute concentrations between two adjacent regions

kinetic energy

the energy an object has due to its motion

solute

substance that is dissolved in a solvent.

solvent

the substance in which a solute a dissolved in (dissolving medium)

facilitated diffusion

diffusion of substances across a cell membrane along a concentration gradient with the aid of membrane proteins

protein channel/channel protein

transmembrane protein pore in the phospholipid bilayer that selectively enables the transport of large/polar molecules

carrier protein

membrane transport protein which undergoes conformational change to passively transport materials across a membrane

conformational change

temporary change to the structure/shape of a macromolecule that allows materials to cross through

osmosis

passive diffusion of water from areas of low solute concentration to high solute concentration

osmolarity

measure of total solvent particles in a solute

tonicity

the ability of a solution to cause a cell to gain or lose water - measure of concentration of solutes on either side of a membrane

hypertonic

having a higher solute concentration than another solution

hypotonic

having a lower solute concentration than another solution

isotonic

having an equal solute concentration as another solution

turgid

(plant cells) swollen/firm due to high water content

plasmolysis

(plant cells) with weak and sagging membranes due to a lack of water

flaccid

(plant cell) soft/loose cell lacking turgidity - isotonic solutions

lyse

the bursting of the cell membrane (due to high intracellular water content)

ion

charged atom - positive or negative charge.

aquaporin

channel/transport protein, that facilitates the passive transport of water

turgor

(plant cells) cell wall pressure generated when the contents of the cell press against the cell wall. regulates water content and protects the cell - prevents lysis