Cellular Transport

1. Cellular Transport

2. Cellular Transport • All particles move and have kinetic energy (energy of motion). • Movement is random and usually in a water solution. • Cells are mostly made of water and there is a constant flow of ions and particles.

3. IV. 2 Types of Cellular Transport • Passive transport = movement of molecules across the membrane by using the molecules kinetic energy. The cell exerts NO energy! • Active transport = transport of materials against the concentration gradient and requires cellular energy.

4. V. Passive Transport • 3 types of passive transport: 1. Diffusion = the net movement of particles from an area of HIGHER concentration of particles to an area of LOWERconcentration of particles.

5. Diffusion… • Molecules move randomly until they are equally distributed. • Diffusion continues until the concentration of substances is uniform throughout.

6. Diffusion… • Dynamic equilibrium – continual movement but no overall change in the concentration; • Movement of materials into and out of the cell at equal rates maintaining dynamic equilibrium with its environment.

8. Diffusion… • Diffusion depends on the concentration gradient. • Concentration gradient is the difference between the concentration of a particular molecule in one area and the concentration in an adjacent area. • Ex: gas exchange in the lungs (oxygen from air to blood and carbon dioxide from blood to air).

10. V. Passive Transport 2. Facilitated Diffusion = type of passive transport that increases the rate of diffusion with the use of carrier proteins. • Ex: Facilitated diffusion of glucose.

11. Facilitated Diffusion

12. How facilitated diffusion works • http://www.youtube.com/watch?v=I4123hUU8xo

13. V. Passive Transport 3. Osmosis = the diffusion of water molecules from an area of HIGH water concentration to an area of LOW water concentration.

14. V. Passive Transport: OSMOSIS • Occurs in response to the concentration of solutes dissolved in water! • Solutes are dissolved substances in a solution. • Cytoplasm is mostly water containing many dissolved solutes.

15. V. Passive Transport: OSMOSIS • Because no TWO molecules can occupy the same space at the same time, the MORE solutes there are in a certain volume of water; the FEWER water molecules there can be in the same water.

16. V. Passive Transport: OSMOSIS • Plant and animal cells behave differently because plant cells have a large water vacuole and a cell wall.

17. How OSMOSIS works • http://www.youtube.com/watch?v=w3_8FSrqc-I

18. V. Passive Transport: OSMOSIS • Ex: Osmosis occurring in a slug (animal) cell.

19. V. Passive Transport: OSMOSIS • Isotonic solution = a solution in which the concentration of dissolved substances (solutes) is the SAME as the concentration of solutes inside the cell. • Osmosis DOES occur since a concentration gradient is not established. Water Continue to move in both directions

20. What happens to cells when placed in an isotonic solution? • Plant cell – becomes normal • Animal cell - normal

21. Animal cell Plant cell

22. V. Passive Transport: OSMOSIS B. Hypotonic solution = a solution in which the concentration of solutes is LOWER than the concentration of solutes inside the cell.

23. What happens to cells when placed in a hypotonic solution? • Animal cell – water will move thru plasma membrane into the cell. This causes the cell to swell and the internal pressure increases. • Cell lyses (bursts)!

24. What happens to cells when placed in a hypotonic solution? • Plant cell – swell • The vacuole and cytoplasm increase in volume • The cell membrane is pushed harder against the cell wall causing it to stretch a little. • The plant tissue becomes stiffer (turgid).

26. V. Passive Transport: OSMOSIS C. Hypertonic solution = a solution in which the concentration of dissolved substances is HIGHER than the concentration inside the cell.

27. What happens to cells when placed in a hypertonic solution? • Animal cell – will shrivel because of decreased turgor pressure.

28. What happens to cells when placed in a hypertonic solution? • Plant cell – will lose water from vacuole and a decrease in turgor pressure will occur; so it is plasmolyzed. • Turgor pressure = internal pressure of a cell due to water held there by osmotic pressure • Plasmolysis = the loss of turgor pressure causing the plasma membrane to pull away from the cell wall • Causes the plant to wilt

30. D. Summary of Cell Behavior in Different Environments:

31. OSMOSIS PROBLEMS First we need to understand 2 vocab words: • Solute – the substance that dissolves (salt, sugar) • Solvent – the substance in which the solute dissolves (water)

32. OSMOSIS PROBLEMS Cell: 5% salt (solute) Environment: 0% salt (solute)

33. OSMOSIS PROBLEMS Cell: 25% salt (solute) Environment: 30% salt (solute)

34. OSMOSIS PROBLEMS Cell: 45% salt (solute) Environment: 45% salt(solute)

35. VI. Active Transport • Movement of molecules from an area of LOW to an area of HIGH concentration. (opposite of passive transport!) • REQUIRES cellular energy! • Moves large, complex molecules such as proteins across the cell membranes.

36. How active transport works • http://www.youtube.com/watch?v=yz7EHJFDEJs

37. VI. Active Transport • Large molecules, food, or fluid droplets are packaged in membrane-bound sacs called vesicles.

38. 2 types of active transport • Endocytosis = process in which a cell surrounds and takes in material from its environment • Used by amoebato feed and white blood cells to kill bacteria

39. 2 types of active transport 2. Exocytosis= expels materials out of the cell, reverse of endocytosis • Used to remove wastes, mucus, and cell products • Proteins made by ribosomes in a cell are packaged into transport vesicles by the golgi apparatus • Transport vesicles fuse with the cell membrane and then the proteins are secreted out of the cell (ex: insulin)

40. Exocytosis

41. How endocytosis and exocytosis works • http://www.youtube.com/watch?v=DuDmvlbpjHQ

42. Identify the following….