Transport Across the Membrane (6.3)

1. Transport Across the Membrane (6.3)

2. 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

3. Crossing the Border 1. Passive Transport • (no NRG required) • High Concentrations to Low • Diffusion • Facilitated Diffusion • Osmosis 2. Active Transport • (NRG required) • Low Concentrations to High

4. Passive Transport • No energy use • Random motion and concentrations Difference in concentration of a substance = the concentration gradient • If a solution is in “Equilibrium”… • concentrations are equal • The movement of substances from: “high concentrations to low concentrations” It is called: “Down the concentration gradient”

5. No NRG Needed here brah’ Slide O’ Science The Passive Transport High Concentration Low Concentration Down The Gradient

6. 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

7. Diffusion in Picture

8. Osmosis • A type of Passive Transport (Diffusion) • Specifically the diffusion of water • 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

9. Water Hypertonic solution If there is a high concentration of solutethere must then be a LOW concentration of water!! Hyper = more solute Hypo = more H2O What is the direction of the flow of water?

10. Water Hypotonic solution

11. Isotonic Solution

12. Quick Review • A hypertonic cell would have a higher concentration of solute than the solution it is in? • Yes, hyper = more solute • In a hypotonic solution, the movement of water is into the cell? (True or False?) • Water moves from High to Low • HYPO = More H2O, • TRUEwater moves INTO the cell

13. 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! Facilitated Diffusion Why? Hydrophobic Area

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

15. Review • What are the 3 types of passive transport • What are the 3 ways water can move across a membrane? (osmosis) • Does passive transport move up or down the concentration gradient?

16. 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

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

18. Exit Ticket • What are the 2 types of transport across the membrane called? • What are the types 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?