1. Lecture 2.1: Membranes and Transport
Unit 2– The Working Cell
Lecture 2.1: Membranes and Transport

2. Membranes and Chemical Activities
Selective permeability
Structure
Phospholipid bilayer
Hydrophilic head
Hydrophobic tail
Phospholipids in water

3. Which molecules get through??
Nonpolar
Polar
Fluid mosaic model…the fluid part of the model

4. The mosaic part of the model
Glycoproteins and glycolipids

5. Proteins and functions

6. Passive Transport Diffusion No energy (passive transport)
Down the concentration gradient
Example in cells

7. Osmosis Passive transport of water Hypertonic solutions
Hypotonic solutions
Isotonic solutions

8. Osmoregulation
Cells in hyper/hypotonic solutions

9. Facilitated diffusion
Down the gradient, with help
Transport proteins
Ex: sugars, amino acids, water

10. Active transport Uses energy Transport proteins work against gradient
with ATP as the
energy source
Na+ and K+

11. Proton pumps
Coupled transport

12. Exocytosis and endocytosis
Getting rid of big molecules
Bringing big molecules in

13. Types of endocytosis Phagocytosis Pinocytosis
Receptor-mediated endocytosis