Diffusion – Osmosis, Passive, Active

Simple Diffusion (what is it?)

direct movement of a solute across the semi permeable (differentially permeable) membrane – driven by a concentration gradient, solute diffuses from side with higher concentration to side with lower concentration

Osmosis (Passive – NO Energy Required)

movement of water across a membrane due to imbalance in solute concentrations

(Water moves from high concentration of water → low concentration of water–where there is less water)

Passive Transport (Passive – NO Energy Required)

Transport/Diffusion that does NOT require cellular energy – moves based on concentration gradient

(high → low concentration)

Facilitated Diffusion (Passive – NO Energy Required)

molecules move across a cell membrane through specialized proteins without using cellular energy – still moves based on concentration gradient

(high → low concentration)

Active Transport (Energy Required)

movement of molecules or ions across a cell membrane from an area of lower concentration to an area of higher concentration, going against the concentration gradient

(low → high concentration)

Primary Active Transport (Energy Required)

uses cellular energy (ATP), to move molecules or ions across a cell membrane against their concentration gradient – uses ATP directly

(low → high concentration)

Secondary Active Transport (Energy Required)

movement of molecules across a cell membrane against their concentration gradient by using the energy stored in the concentration/electrochemical gradient, rather than using ATP directly – uses ATP indirectly

(low → high concentration)