1. Active Transport IB Biology

2. Key Words Active transport Sodium-Potassium pump Endocytosis Exocytosis ATP Pinocytosis Phagocytosis Intracellular vesicle Concentration gradient

3. Active Transport “The movement of molecules and ions across the plasma membrane from a low to a high concentration” Works against the concentration gradient

4. Active transport and the cell Active transport can involve substances being actively pumped into or out of a cell

5. Role of the plasma membrane in active transport Certain protein molecules present in the plasma membrane act as CARRIER PROTEINS Carrier proteins (pumps) recognise specific ions and transfer them across the plasma membrane Energy for this process supplied by ATP which is made during respiration

8. Sodium-Potassium Pump Exchange one type of an ion for another Actively pumps out sodium ions Actively pumps in potassium ions Process occurs simultaneously

9. GROUP THOUGHT: What are the optimum conditions required for active transport to take place at the maximum possible rate? CONSIDER: Temperature Availability of oxygen Concentration of respiratory substrate (e.g. glucose) If a factor directly affects a cell’s respiration rate then it will also affect the rate of active transport

10. Endocytosis 1.Cell engulfs and takes in relatively large quantities of materials 2.Plasma membrane folds inwards to become a ‘pouch’ 3.Pouch closes off and detaches from the cell membrane -Now known as an intracellular vesicle

11. 2 types of endocytosis: 1.Phagocytosis (cell-eating)Phagocytosis -engulfing of large solid particles (e.g. bacteria by white blood cells) -contents of vesicle are then digested

12. 2.Pinocytosis (cell-drinking) -formation of small liquid –filled vesicles by cell membrane -means by which a cell often acquires hormones, lipids and proteins

13. Exocytosis Reverse of endocytosis Vesicles formed inside the cell fuse with plasma membrane This allows their contents to be expelled from the cell Intracellular products like hormones, enzymes and glycoproteins can be secreted from the cell

16. Watch a summary of these processes!