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Active and Passive Transport

Active and Passive Transport. Chapter 5. 1. Passive Transport . Movement of materials in and out of the cell Requires no energy to happen. Two Types of Passive Transport. Diffusion: When substance moves that is dissolved in water Osmosis: When water moves across the membrane.

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Active and Passive Transport

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  1. Active and Passive Transport Chapter 5

  2. 1. Passive Transport • Movement of materials in and out of the cell • Requires no energy to happen

  3. Two Types of Passive Transport • Diffusion: When substance moves that is dissolved in water • Osmosis: When water moves across the membrane

  4. Solutions are made of 2 parts: • Solute: Substance that is dissolved in water • Solvent: Liquid it is dissolved in (usually water)

  5. Next answer some questions about the pictures on your paper…

  6. Vocab: • Hypertonic:More solutes than the other solution • Hypotonic: Lesssolutes than the other solution • Isotonic: Equal solutes as another solution • Now go back to the pictures above and label the cell and the environment around it as one of the vocab words

  7. Molecules of dye Membrane (cross section) WATER Equilibrium Net diffusion Net diffusion Net diffusion Equilibrium Net diffusion Osmosis Net diffusion Net diffusion Equilibrium (a) (b)

  8. Lower concentration of solute (sugar) Higher concentration of sugar Same concentration of sugar Selectively permeable mem- brane: sugar mole- cules cannot pass through pores, but water molecules can Water molecules cluster around sugar molecules More free water molecules (higher concentration) Fewer free water molecules (lower concentration) Osmosis  Water moves from an area of higher free water concentration to an area of lower free water concentration

  9. Describing a solution • Hypotonic: when a solution is less concentrated than another solution • Example: if around a cell is hypotonic, then water will move into the cell. • Can cause a cell to get so large it may burst (cytolysis)

  10. Hypertonic: When a solution is more concentrated than another solution • If around a cell is hypertonic, water will move out of the cell • Can cause the cell to get very small (in plants will see plasmolysis: wilting)

  11. Isotonic: when two solutions have the same concentration (are at equilibrium) • Causes water to move in and out equally • The cell maintains its shape

  12. Hypertonic solution Hypotonic solution Isotonic solution (a) H2O H2O H2O H2O Normal Shriveled Lysed H2O H2O H2O (b) H2O Turgid (normal) Flaccid Plasmolyzed

  13. Osmosis • Water moves trying to balance out concentrations • Goes from where there is more water to less water

  14. What if….. • Environment around a cell is hypotonic. What direction will the water move? • Salt?

  15. What if….. • The environment around a cell is hypertonic. • What direction will the water move? • Salt?

  16. 2. Active Transport • Requires energy • Goes against the concentration gradient (from lower concentration to higher concentration)

  17. Figure 7.16 The sodium-potassium pump: a specific case of active transport Cytoplasmic Na+ binds to the sodium-potassium pump. EXTRACELLULAR FLUID [Na+] high [K+] low Na+ binding stimulates phosphorylation by ATP. Na+ Na+ Na+ Na+ Na+ [Na+] low [K+] high ATP P Na+ 5 2 1 6 4 3 ADP CYTOPLASM Phosphorylation causes the protein to change its conformation, expelling Na+ to the outside. K+ is released and Na+ sites are receptive again; The cycle repeats. Na+ Na+ Na+ K+ P K+ Loss of the phosphate restores the protein’s original conformation. Extracellular K+ binds to the protein, triggering release of the Phosphate group. K+ K+ K+ K+ P P i

  18. Sodium Potassium Pump • Cells usually have more sodium ions outside and more potassium ions inside • Pump increases number of ions where concentration is already high

  19. When substances are too large to pass through the cell membrane, use endocytosis or exocytosis • Membrane folds around substances and release into cell or out of cell

  20. PHAGOCYTOSIS EXTRACELLULAR FLUID 1 µm CYTOPLASM Pseudopodium Pseudopodium of amoeba “Food” or other particle Bacterium Food vacuole Food vacuole An amoeba engulfing a bacterium via phagocytosis (TEM). PINOCYTOSIS 0.5 µm Plasma membrane Pinocytosis vesicles forming (arrows) in a cell lining a small blood vessel (TEM). Vesicle Figure 7.20 Exploring Endocytosis in Animal Cells

  21. Endocytosis • Material moved into cell • Forms vesicle • Pinocytosis: Liquids • Phagocytosis: Solids

  22. Exocytosis • Material released to outside of cell

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