1. Structure and Function
Cell Membranes
Structure and Function

2. Animal Cell Membrane

4. Semi-permeable Membranes
Cell membranes are semi-permeable, also called selectively permeable
Water moves across the membrane freely
Small molecules like oxygen and carbon dioxide diffuse through the phospholipids
Sugars and amino acids diffuse through channel/transport/carrier proteins
Ions (charged particles) do not move across the membrane freely
Macromolecules do not move across the membrane freely

5. Passive Transport
Diffusion – the movement of substances from an area of higher concentration to an area of lower concentration
Osmosis – the movement of water from an area of higher water content to an area of lower water content
Tonicity : Hypertonic, Hypotonic, & Isotonic Solutions

6. Active Transport
The movement of a substance against the concentration gradient (from lower concentration to higher concentration
Active transport requires the use of energy

7. Membrane proteins play an important role in passive and active transport

8. Very large molecules may be taken in by endocytosis

9. Exocytosis secretes substances

10. Cellular Tunes