1. 1.4 Membrane transport

2. A membrane is a barrier. Almost all membranes are semi-permeable. Why?

3. Particles are moved across a membrane in four ways: 1.Simple diffusion 2.Facilitated diffusion 3.Osmosis 4.Active transport

4. 1. Simple diffusion Particles moving from high to low concentrations, particles moving down a concentration gradient. Passive process. Particles move between phospholipids Oxygen can move easily (non-polar molecule). Small polar molecules can pass relatively easily (at a low rate) but larger polar molecules e.g. urea, pass much more slowly. See fig. 6. pg. 36

5. 2. Facilitated diffusion Particles moving through specific channels in the membrane. These channels are typically very narrow, the diameter of the protein channel determines what type of molecule is able to pass through. Passive process. High to low concentration, movement down a concentration gradient. Cells are able to control which types of channels are synthesised, which in turn controls diffusion in/out of the cell. http://highered.mheducation.com/sites/0072495855/student_v iew0/chapter2/animation__how_facilitated_diffusion_works.ht ml

6. 3. Osmosis Movement of water, water moves freely. The net movement of water is known as osmosis. Intermolecular forces (e.g. hydrogen bonds) between substances dissolved in water can restrict its movement. If something has a high concentration of solutes, it will have a low concentration of water. Passive process. High to low centration, down the concentration gradient. http://highered.mheducation.com/sites/0072495855/student _view0/chapter2/animation__how_osmosis_works.html

7. 4. Active transport Substances absorbed against the concentration gradient. Low to high concentration. Active process – REQUIRES energy (uses ATP). Globular proteins inside the membrane (pump proteins) Fig. 10, pg. 38 http://highered.mheducation.com/sites/0072495855/ student_view0/chapter2/animation__how_the_sodiu m_potassium_pump_works.html

8. Read text book pages, find examples of passive/active transport McGraw hill animation, endo/exocytosis? Passive/active transport Design lab???

9. What does passive transport mean? Examples? Task How would you design an experiment to test osmosis?

10. Carrier proteins inside the membrane, carrier proteins combine with a substance/molecule and transport it across the membrane. Does not require energy Very specific

11. Write a short paragraph to explain the difference between Diffusion (simple), Facilitated diffusion & Osmosis

12. Requires energy Moves molecules against the concentration gradient Uses pumps Read pg. 35/36. Summarise the process into a short paragraph

13. Part of the membrane ‘pinches’ off forming a vesicle to transport incoming molecules within the cell.

14. Vesicle joining the membrane, releasing contents into extracellular region