7 - Cells

1. 7 - Cells 7.3 – Cell Transport

2. To function, all cells must regulate what enters and exits the cell

3. Passive Transport • Movement of material across the membrane without the use of energy • Molecules move from high concentration to low concentration solutions • Solution – mixture in which all of the particles are evenly distributed

4. Active Transport • Movement of material in or out, against the concentration gradient, which requires energy • Concentration gradient – difference in the concentration of a solution across a boundary • Molecules go from low concentration to high concentration

5. Passive Transport

6. Diffusion • Movement of molecules in a solution from an area of high concentration to an area of low concentration, down its concentration gradient (difference) • Moves until concentration reaches equilibrium (equal throughout)

7. Even at equilibrium, molecules are still moving around, but concentration will not change

8. In cells, molecules that can pass through membrane will diffuse in and out based on concentration (O2 + CO2)

9. Facilitated diffusion • Large molecules (such as glucose) diffuse through protein channels in membrane • Channels help (facilitate) them diffuse • Some channels only allow certain molecules through (they are specific)

11. Osmosis • Movement of water across a membrane, from high water concentration to low water concentration • Based on solute concentration • Solute – part of the solution that is dissolved into the liquid (ex: the salt in saltwater) • Solvent – the liquid part of a solution that dissolves another substance (ex: the water in saltwater)

12. Moves from low solute concentration (high water conc.) to high solute concentration (low water conc.)

13. Osmotic pressure – force of water pressing on the membrane of a cell

14. Comparing solutions: • Terms used to compare the concentration of one solution to another: • Hypertonic – more concentrated than… • Hypotonic – less concentrated than… • Isotonic – equal concentration

15. Cells and Osmosis • When cells are placed in a… • Hypotonic solution (solution is less concentrated than cell) • Water will move into the cell • Cell will swell because of increased water • Animal cell – cell may burst if osmotic pressure increases • Plant cell – cell wall prevents cell from bursting

16. When cells are placed in a… • Hypertonic solution (solution is more concentrated than cell) • Water will move out of the cell • Cell will shrivel because of decreased water • Animal cell – whole cell shrivels • Plant cell – Inner membrane shrivels, cell wall holds shape

17. When cells are placed in an… • Isotonic solution (solutions are the same concentration) • Water will move in and out of the cell equally

19. Active Transport

20. Active Transport • Movement of material in or out, against the concentration gradient, which requires energy • Concentration gradient – difference in the concentration of a solution across a boundary • Molecules go from low concentration to high concentration

21. Molecular transport • Protein pumps – proteins in membrane carry large molecules and ions across membrane

22. Bulk transport • Large molecules and solids are taken in through membrane

23. Endocytosis – • Materials taken in by forming pockets in membrane • Pocket deepens until it forms a vesicle or vacuole, containing the material

24. Phagocytosis – food particles taken in, and forms a food vacuole • White blood cells do this to destroy damaged cells and contaminants (bacteria) • Pinocytosis – liquid is taken in to form vacuole

25. Exocytosis – • Vesicle containing material fuses with cell membrane and releases the material out of cell

26. Endocytosis and Exocytosis