Cell Transport Mechanisms

1. Cell Transport Mechanisms

2. Moving molecules across the Cell Membrane Two methods: Passive Transport Active Transport

3. Passive Transport Allows molecules to ____________ according to natural laws of physics Everything tends towards___________ Three types of passive transport mechanisms: - - -

4. Passive Transport – Diffusion Movement of molecules is __________ When they bump into each other, they _________________ When they are __________ concentrated, they bump into each other _____________________ This forces molecules to move from areas of ________ concentration to areas of ________ concentration High Concentration _________a ___________________ “_______________” Low Concentration

5. Passive Transport – Diffusion = ___________ When molecules have reached equal concentrations in both locations, diffusion ends. Molecules _________ moving, but they move in ______________ equally. _________________.

6. Diffusion across a Membrane Examples: small molecules (CO2,O2) small lipids alcohol Prediction? Prediction?

7. Passive Transport – Osmosis Moves ________ molecules across cell membrane (into or out of cells) Molecules still move down the concentration gradient Purple dots are solutes, not water molecules

8. Passive Transport – Osmosis Predict Results

9. Passive Transport – Osmosis Osmotic Pressure – Pressure created by the presence of water in the cell …cell _______or ________ Example: Blood cell in low/high salt solutions

10. Passive Transport – Osmosis Hypertonic Solution: Conc. of solutes outside cell is ________ Animal Cell 5% salt 2% salt Plant Cell Water _______ cell

11. Passive Transport – Osmosis Isotonic Solution: Conc. of solutes outside cell is _________inside cell Animal Cell 5% salt 5% salt Plant Cell Water ____________cell _____________ _____ _______ ______________

12. Passive Transport – Osmosis Hypotonic Solution: Conc. of solutes outside cell is _________ Animal Cell 2% salt 5% salt Plant Cell Water ________ cell

13. Passive Transport – Facilitated Diffusion Molecules still move down the concentration gradient, but cannot pass phospholipids on their own. Rely on __________ imbedded in membrane to “________” them across Proteins are specific to _____________________________________ _____________ ______________ Examples: water salt ions glucose

14. Active Transport Moves molecules __________ the concentration gradient from areas of _________ concentration to areas of __________ concentration. Restores ________ Takes _______ to “go _______” _____________move molecules into or out of cell ______ gradient. Outside Cell Inside Cell

15. Active Transport Endocytosis Moving molecules ________cells ___________: “cellular _________” ___________: “cellular _________” Exocytosis Moving molecules _____cells

16. Endocytosis Molecules move into a “pocket” of the cell membrane

17. Endocytosis “Pocket” pinches off the membrane into cytoplasm

18. Endocytosis ________ has now formed and can move around inside cell

19. Exocytosis _______ pinches off ________________

20. Exocytosis Free vesicle migrates towards cell membrane

21. Exocytosis Vesicle contacts cell membrane and begins to fuse with it

22. Exocytosis As vesicle becomes part of plasma membrane, contents spill out of cell

23. Endocytosis and Exocytosis These two processes occur at roughly the same rate = __________________________________________