1. Teaching the Concept of Cell Membrane Transport: Na/K pump By Christel Mokono

2. Reminder What is a cell membrane? ► The cell membrane = plasma membrane = a biological membrane that separates the interior of all cells from the outside environment.

3. Lesson 1: Membrane structure Lesson 2: Functions Lesson 3: Diffusion, Osmosis Lesson 4: How molecules cross membranes Lesson 5: The sodium-potassium pump Lesson Sequence ► Membrane transport of large particles ► Transport by membrane proteins

4. Membrane Structure All biological membrane consist mainly of lipids and proteins

5. Membrane Functions Two main functions: ► They form a physical barrier around a cell or organelle, and ► They control the passage of substances into or ‘out of the enclosed area.

6. Diffusion, Osmosis. Key words: osmotic potential, hypotonic, hypertonic, isotonic, concentration gradient, selectively permeable. ► Diffusion = process whereby molecules of two or more substances move about and become evenly mixed. ► Osmosis = process by which water moves through a diffusion of a solvent, such as water, rather than the diffusion of substances dissolved in the solvent.

7. How molecules cross membranes ► Membrane transport of large particles Large particles can move through membranes because the membrane can change shape, pinching of small sacs containing the particles and then automatically resealing itself.

8. ► Transport by membrane proteins ► Some membrane proteins form channels through which substances can cross the membrane by diffusing down their concentration gradients.

9. Active Transport: The Sodium-Potassium Pump - Carrier proteins, some of which require energy, transport some substances through membranes. -The sodium-potassium pump is set of proteins in the plasma membrane that maintains this electrical difference. The pump uses energy from ATP to transfer sodium (Na + ) out of the cell and potassium (K + ) in, moving both against their concentration gradients. Transport of these ions is linked as shown under the following link. (To be visualized !!) http://lessons.harveyproject.org/development/general/transport/Na- K/step%206.htm http://lessons.harveyproject.org/development/general/transport/Na- K/step%206.htm

10. Curriculum Expectations e3.1 explain the anatomy of the respiratory system and the process of ventilation and gas exchange from the environment to the cell (e.g., the movement of oxygen from the atmosphere to the cell; the roles of ventilation, hemoglobin, and diffusion in gas exchange). e3.2 explain the anatomy of the digestive system and the importance of digestion in providing nutrients needed for energy and growth (e.g., the body’s mechanical and chemical processes digest food, which provides the proteins needed to build muscle, and the fibre, water, vitamins, and minerals needed to regulate body processes). e3.3 explain the anatomy of the circulatory system (e.g., blood components, blood vessels, the heart) and its function in transporting substances that are vital to health.

11. Learning/ Teaching strategies The L/T strategies are based on small-group research projects followed by a presentation. The following topics are assigned to students and each group works on of them. ► Diffusion ► Osmosis ► Passive transport ► Active transport ► Na + /K + pump