3.5 Passive Transport vs. Active Transport

1. 3.5 Passive Transport vs. Active Transport • Passive Transport: requires NO energy. • Diffusion (dialysis and osmosis) • Facilitated diffusion • Active Transport: requires energy • Active Transport • Endocytosis/Exocytosis

2. Passive Transport • Diffusion and Osmosis require no energy • (Passive Transport)

3. Passive Transport • Some molecules are too large to fit through the phospholipid bilayer. They can only diffuse through proteins. (This is still Passive Transport.) • Facilitated diffusion is diffusion through proteins in the cell membrane. • Example: glucose

4. Active Transport • Active transport uses energy to move things against its concentration gradient. • Active transport occurs through protein pumps. • Energy allows the protein to change shape and pump molecules against the concentration gradient

5. Active Transport: Sodium/Potassium Pump • For Example: • For nerve cells to function properly, there must be a higher concentration of Na outside and higher concentration of K inside the cell

6. Sodium Potassium Pump • (See animation)

7. Endocytosis and Exocytosis • If the material is too large to move through the protein, it must enter/exit in a different way. • Endocytosis(material entering cell) • Examples: food into amoeba, white blood cells • Steps: • Material surrounded by cell membrane • Vesicle pinches off from cell membrane • Vesicle enters cell, contents are released • Empty vesicle digested by lysosome

8. Endocytosis

9. Exocytosis • Exocytosis • Moving material out of the cell. • Examples: protein exported, nerve cells • Steps: • Material in the cell is packaged by the Golgi • Vesicle joins with the cell membrane • Contents are dumped outside the cell and the membrane closes back up

10. Exocytosis