1. BIOLOGY
Unit 2 Notes:
Cell
Membrane
Transport

2. (1) Cell Membrane Transport
• Why Do Cells Do This?
Cells need to move useful nutrients /
molecules in and out of the cell .
• Types:
– Diffusion
– Facilitated Diffusion
– Osmosis
– Active Transport

4. (2) Diffusion
• Movement of particles from high to low
concentration, across a concentration
gradient, until reaching equilibrium.
• Does NOT require any energy (or ATP).
• Picture:

6. (3) Facilitated Diffusion
• The assisted movement of large molecules
across protein channels, from high to low
concentration, until reaching equilibrium.
• Does NOT require any energy (or ATP).
• Picture:

8. (4) Osmosis
• The diffusion of water.
• The movement of water molecules from
high to low concentration, across a
gradient, until reaching equilibrium.
• Does NOT require any energy (or ATP).
• Picture:

10. (5) Osmotic Environments
• Isotonic:
Equal amounts of water
inside and outside the
cell.
-PICTURE-
• Hypertonic:
Higher concentration of
water inside the cell, than
outside.
-PICTURE-
• Hypotonic:
Lower concentration of
water inside the cell, than
outside.
-PICTURE-

12. (6) Active Transport
• The forced movement of particles, AGAINST
a gradient, from low to high concentration.
• Requires the use of energy (or ATP).
• Picture: