Move it!

1. Move it! • Materials such as water, nutrients, dissolved gases, ions, and wastes must constantly move in two-way traffic across a cell's plasma membrane. • Cellular membranes function like gatekeepers, • letting some molecules through but not others. • while certain molecules pass freely through the "gates," others move only when the cell expends energy

2. Crossing the Border • Passive Transport (no energy required) • Moves from high to low concentration. • Diffusion • Osmosis • Facilitated Diffusion • Active Transport (energy required) • Low Concentrations to High

3. Passive Transport • No energy needed to move material. • Random motion and concentration of molecules. The difference in the concentration of the substance is called the concentration gradient Movement of substances is from: “high concentrations to low concentrations” “Down the concentration gradient” because the material wants to be in equal amounts inside and outside of the cell.

4. No NRG Needed here yo’, Slide O’ Science The Passive Transport High Concentration Low Concentration Down The Gradient

5. Examples of Diffusion • Food coloring • Will gradually move through uncolored water… • WHY? • Concentrations WANT to be in equilibrium • Water turns a light blue • Air Freshener • Will gradually spread to all • WHY? • Concentrations WANT to be in equilibrium • Is why scent is strong at first and then gets weaker

6. Diffusion in Picture

7. Osmosis This is the diffusion of water through a cell membrane. • 3 Ways this can occur • #1 Water diffuses out of cell • Hypertonic solution • #2 Water diffuses into a cell • Hypotonic solution • #3 No net movement of water • Isotonic solution

8. Water Hypertonic solution Look at the water – there is more space for water inside the cell than inside the cell because of the solid. Therefore, the water moves out of the cell into the solution. Cell will Shrink!

9. Water Hypotonic solution Look at the water – there is more space for the water outside the cell than inside the cell because of the solid. Therefore, the water moves into the cell. Cell will swell!

10. Isotonic Solution There is an equal amount of water inside and outside of the cell. This means that there is an equal amount of water moving inside and outside. The cell will stay the same size!

11. The Crossing Guards of the Membrane • Transport Proteins!! • channels” allow those substances to cross that cannot on their own: • Ion Channels allow K+ and Na- to cross into cell • Some channels always open • some open in response to stimulus • Still no use of energy! Why? Hydrophobic Area

12. Facilitated Diffusion • Carrier proteins transport substances “down their concentration gradient” • Move down gradient with NO energy use

13. ACTIVE TRANSPORT • RequiresNRG to be used by the cell… Why? • UP the concentration gradient • specific transport protein pumps opposite direction of diffusion • requires chemical energy supplied primarily by the mitochondria! • How your nerve cells work! NRG

14. Phew! This takes too much WORK Slide O’ Science The Active Transport High Concentration Low Concentration UP The Gradient

15. Exit Ticket • What are the 2 types of transport across the membrane called? • What are examples of Passive transport? • Contrast Passive transport and Active Transport. • Where does the NRG come from for Active Transport? • Which direction on the concentration gradient does active and passive transport move?