1. Types of Cellular Transport
Animations of Active Transport & Passive Transport
Passive Transport
cell doesn’t use energy
Diffusion
Facilitated Diffusion
Osmosis
Active Transport
cell does use energy
Protein Pumps
Endocytosis
Exocytosis
high
low
Weeee!!!
high
low
This is gonna be hard work!!

2. Movement of molecules
Cell membranes only allow some molecules across w/out help:
• Small, non-polar molecules OK
ex. steroids, O2, CO2
• No charged, polar, or large molecules
ex. sugars, ions, water*

3. Movement of molecules
Simple Diffusion: most basic force to move molecules
• Disperse until concentration equal in all areas

4. Transport Across Membranes
Types of transport:
Passive transport
- Simple diffusion
- Facilitated diffusion
- Osmosis
B. Active transport
C. Bulk transport
• Energy Required?
• Directionality?

5. Passive Transport - Simple Diffusion
• NO ENERGY required
- non-polar molecules (steroids, O2, CO2)
• DOWN concentration gradient
• molecules equally distribute across available area by type

6. Passive Transport – Facilitated Diffusion
• NO ENERGY required
• DOWN concentration gradient
• molecules equally distribute but cross membrane with the help of a channel (a) or carrier (b) protein.

7. Passive Transport - Osmosis
• osmosis – movement of water across cell membrane
• water crosses cell membranes via special channels called aquaporins
• moves into/out of cell until solute concentration is balanced

8. Passive Transport - Osmosis
Paramecium example
• regulate water balance
• pond water hypotonic
• water into contractile vacuole
– water expelled

9. Passive Transport - Osmosis
Scenario: in movie theater, watching a long movie.
You are: drinking water
What happens to your blood?
You are: eating popcorn
What happens to your blood?

10. Active Transport • Ex. Na-K ion pump • ENERGY IS required
- Na+ ions: inside to out
• UP/AGAINST concentration gradient
- K+ ions: outside to in
• transport proteins
a. ion pumps (uniporters)
• antiporter: two molecules move opposite directions (UP gradient)
b. symporter/antiporter
c. coupled transport