Cells at Work Active Transport

Active Transport Your cells at work!!! Even though cells utilize passive transport to move most molecules into the cell, there are times when it is necessary for a cell to move molecules against their concentration gradient. Active transport is the movement of molecules from a low concentration area (less crowded) into a high concentration area (more crowded). This type of movement requires energy. To remember the difference between active versus passive transport, you can think of it like riding a bike up or down a hill. If you are riding a bike uphill (from low to high) it requires energy - like Active Transport. If you are riding a bike downhill (from high to low) it does not require energy like Passive Transport! ***Knowing the difference is an essential skill for this unit. There are many times that the cell must move "stuff" against the concentration gradient. For example, your nerve cells will only send signals if there is a high concentration of sodium ions outside the cell and a high concentration of potassium ions inside the cell. In order to move molecules into high concentrations, the cell uses protein pumps. (The sodium/potassium pump is the name of the protein that prepares your nerve cells to send signals!) These pumps require energy (ATP) to force these ions through the cell membrane into already high concentrations. When molecules are just too big to fit through the cell membrane or even through a membrane protein, your cell must do some serious work to get that "stuff" in or out. Some cells have the ability to wrap its' cell membrane around a particle in order to pull it into the cell. This process is called endocytosis - when the cell membrane wraps around a particle to pull it into the cell. When your cells use endocytosis to pull in solid particles it is called phagocytosis. When your cells use endocytosis to pull in liquid particles, it is called pinocytosis. Your body's immune system utilizes phagocytosis to catch foreign invaders. You have white blood cells that will simply engulf bacteria or other foreign invaders by phagocytosis! You also have many cells that produce proteins for export from the cell. Your cell will release large quantities of "stuff" using the cell membrane in a process called exocytosis. Exocytosis is basically the reverse of endocytosis - exocytosis exiting the cell, endocytosis into the cell. In short, all methods of active transport must push molecules against their concentration gradients using energy. Protein pumps move smaller molecules through the cell membrane. Endocytosis and Exocytosis, use the cell membrane to engulf substances then move them in or out of the cell. All of these methods use energy (ATP)!!! 1. Color the following picture that shows active transport using phagocytosis: PHAGOCYTOSIS. AMOEBA. AMOEBA CELL MEMBRANE. VACUOLE MEMBRANE.. PREY. B B NUCLEUS 2. What types of cells need to have a high concentration of sodium ions outside the cell and a high concentration of potassium inside the cell? (Na) (Na) ← No 3. What type of active transport is shown in this picture? (NC) 4. What direction are molecules being moved in active transport? ACTIVE TRANSPORT. POTASSIUM IONK. 5. Where in the cell are Protein Pumps located? SODIUM IONNG 6. What is the difference between Endocytosis and Exocytosis? 7. Why is it important that you have white blood cells that perform endocytosis? 8. What transport method do you think the Golgi apparatus uses to ship packages of proteins out of the cell? 9. What is the difference between Phagocytosis and Pinocytosis? 10. Use the bicycle analogy to explain the differences between active and passive transport. NA