2. ACTIVE TRANSPORT

3. In many cases, cells must move materials from an area of lower concentration to an area of higher concentration. Higher conc Lower conc

4. Example: Sodium-Potassium Pump Animal cells must pump potassium ions into their cells, although the concentration inside the cell is higher than outside.

5. Potassium, who cares! Potassium is essential for: nerve conduction muscle contraction regulates heartbeat, and more…

6. Active transport the movement of substances through a membrane from a region of lower conc to a region of higher conc. Higher conc Lower conc requires ENERGY Active transport requires energy, in the form of ATP. Lower Higher

7. Active transport uses transport proteins powered by chemical energy. ATP Each transport protein transport a specific molecule. Transport Protein

8. Some substances, such as macromolecules, are too large to pass through the cell membrane by regular transport. These substances are moved across the cell membrane by vesicles. I’m too BIG Vesicle

9. Endocytosis and exocytosis are transport mechanisms that transport large substances. Endocytosis and exocytosis require energy so they are types of active transport. Endocytosis Exocytosis ATP

10. Endocytosis is the process of taking large substances into a cell by engulfing them in a membrane. Endo --- Enter ENDOCYTOSIS ATP

11. Steps in Endocytosis: (1) (2) (3) (1) The cell membrane folds inward surrounding the substance in a pocket. (2) The pocket pinches off inside the cell forming a vesicle. (3) The vesicle fuses with a lysosome where the enzyme s break down the contents.

12. Endocytosis

13. Example (1): Some white blood cells called macrophages engulf and destroy bacteria by endocytosis.

14. Example (2): Some unicellular organisms, such as amoebas, take in food by endocytosis.

15. Exocytosis is the release of a substance out of a cell by the fusion of a vesicle with the membrane. Cells also use this method to expel waste products, or toxins. Cells use this method to secrete substances such as proteins, hormones, and other materials produced in the cell. Exo --- Exit

16. Exocytosis is the release of a substance out of a cell by the fusion of a vesicle with the membrane.