Traffic across Membranes

1. Traffic across Membranes BY: Sarah Walsh & ArianaDubov

2. Solute Transport Passive Transport (requires no energy) • Simple Diffusion ~ goes along gradient • Diffusion with a Channel Protein ~ protein acts like a bridge that molecules go through • Diffusion with a Carrier Protein ~ carrier protein is specific to what binds to it ~ protein receptor recognizes molecule and carries it across membrane • DIFFUSION WITH CHANNEL & CARRIER PROTEINS ARE FASCILITATED DIFFUSION Active Transport (requires energy) • goes against gradient • high --> low concentration • Endocytosis • Exocytosis

3. Types of Passive Transport Diffusion with a Channel Protein Diffusion with a Carrier Protein

4. Types of Active Transport Endocytosis Exocytosis Materials from inside the cell get transported outside the cell Ex: when lysosomes break down material inside a cell to get rid of them; vesicles carrying the material fuse with the cell membrane and the particles are released • Materials from outside the cell get transported inside the cell • a) PHAGOCYTOSIS: transport of solid particles b) PINOCYTOSIS: transport of liquid particles

5. Phagocytosis & Pinocytosis

6. Endocytosis & Exocytosis

7. PRACTICE The above picture is an example of: Endocytosis Exocytosis

8. PRACTICE The picture on the right is an example of: Active Transport Passive Transport Fascilitated Diffusion

9. PRACTICE The picture on the right is an example of: Active Transport Fascilitated Diffusion

10. Osmosis • Osmosis ~process where molecules of a solvent pass through a semi-permeable membrane from a solution with a lower concentration to a more concentrated one. ~this process makes the concentrations on each side of the semi-permeable membrane equal. • Isotonic Osmosis ~ When the solute has the same concentration and water potential on both sides of the membrane. Therefore, there is equal flow between the membrane. • Hypotonic Osmosis ~ When the solution has a lower concentration inside the membrane than the solution outside of the membrane. Therefore, there is more flow going into the membrane. • Hypertonic Osmosis ~ When the solution has a higher concentration inside the membrane than the solution outside of the membrane. Therefore, there is more flow going out of the membrane.

11. Types of Solutions

12. Osmosis in Plant & Animal cells Plant Osmosis Animal Osmosis Animal cells osmosis helps animal cells by balancing between important minerals & body solutions when there is too much of a solution inside an animal cell, it will burst, unlike a plant cell, due to it not having a cell wall animal cells need to be in an isotonic solution so they will neither burst nor shrivel • Plant cells • surrounded by hard cellulose walls • plants cells cannot burst because the cellulose walls limit how much water can move in • plant cells are usually hypotonic

13. Plant & Animal cells

14. PRACTICE 1- What is it called when molecules pass through a semi-permeable membrane from lower concentrations to higher concentrations? 2- What is the difference between Hypotonic Osmosis and Hypertonic Osmosis? 3- When a solution has the same concentration on both sides of a semi-permeable membrane, what is it called? 4- What would happen to a cell if it took in too much water? What would happen if there was too little water?