osmosis and diffusion

1. Introductory Concepts in Biology
Diffusion and Osmosis

2. Diffusion
• Movement of molecules
from high to low
concentration – moves
with the concentration
gradient
• No energy required
• Examples: oxygen and
carbon dioxide

3. Diffusion

4. Diffusion
● Diffusion can occur to move molecules in and out
of a cell through the cell membrane.
● Diffusion can also occur within a cell (or fluid) to
disperse molecules evenly throughout.
● Diffusion requires no additional energy and is
“powered” by the natural motion of the molecules.
– When would equilibrium be reached more quickly?
– https://www.youtube.com/watch?v=9ghYur0vqgE

5. Osmosis
• Special form of diffusion.
• Water moves from high
to low concentration
across a semipermeable
membrane.
• Solute “sucks” water
towards it.
• Movement is from area
of high (water)
concentration to low
(water) concentration.