1. Osmosis, Diffusion, Active Transport
Brigance 2017

2. Diffusion, Osmosis and Concentration Gradient
Diffusion – the movement of a substance from a high concentration to a low concentration
Osmosis – the movement of WATER from a high concentration to a low concentration.
Concentration Gradient – the difference in concentration between a region of high concentration and a region of lower concentration

3. Passive or Active Transport:
Passive Transport - does not require cell energy
Examples: Diffusion, Facilitated diffusion and Osmosis  
Active Transport Requires cell energy (ATP)
Examples: Carrier mediated active transport, Endocytosis and Exocytosis

4. Passive-Diffusion
Diffusion: the random movement of particles of a solute from an area of higher concentration to an area of lower concentration.
Particles always move with (down) a concentration gradient (the difference in concentrations across a membrane).
Accepts small or uncharged molecules (oxygen, carbon dioxide, nitrogen, water, urea, and glycerol).
animations

5. Passive-Facilitated Diffusion
Particles always move with (down) a concentration gradient.
Uses transport/channel proteins.
Usually for specific molecules such as glucose.
Facilitated diffusion stops at equilibrium.

6. Equilibrium
Diffusion stops at equilibrium (when the concentrations across a membrane are equal).
The movement of molecules continues at equilibrium but the # of molecules moving across the membrane remains the same.
The rate of transport is dependent on:
1) if the material is solid, liquid or gas.
2) the size of the molecules.
3) temperature
Examples of molecules that can diffuse through the bilayer: carbon dioxide, oxygen, water but very, very slowly.

7. Active transport Active Transport: requires energy in the form of ATP.
Capable of moving solute particles (UP) against the conc. gradient (from low conc. to high conc.)
carrier proteins (protein pumps) embedded in the plasma membrane.
Carrier proteins are specific for the molecules that they allow through. The carrier protein changes shape which requires energy (ATP).
Accepts Sodium and Potassium. Na+ and K+ through Sodium-Potassium Pumps.

8. Active Transport against the concentration gradient

12. This image represents:
Active Transport
Diffusion
Facilitated Diffusion

13. The three types of passive transport are diffusion, facilitated diffusion, and _____________.

14. Facilitated Diffusion uses __________ ______________ to carry molecules across membrane.

15. T/F: Passive Transport requires energy.

16. Name that term: When the concentrations across the membrane are equal.

17. Equilibrium is the goal of which method of transport?

18. In which direction will the sugar molecules diffuse, left or right?

19. Active transports moves _______ the concentration gradient.

20. Why does active transport require ATP?

21. Osmosis
Osmosis: the diffusion of water through a selectively permeable membrane.
Passive transport
Water molecules move from a higher concentration OF WATER to a lower concentration OF WATER.
Water will move to where there is a greater amount of solute because there is less water there

23. How does a healthy cell look?

24. Isotonic Solution
Isotonic solutions: the concentration of solute and water inside and outside of the cell is the same.
Isotonic:
Water in = Water out
No net movement of water.
Molecules in equilibrium.
Normal state for animal cells.
Cell in homeostasis.

26. Hypotonic Solution
Hypotonic solutions: the concentration of solute is lower outside the cell than inside the cell.
Have more water outside the cell so water moves into the cell
Causes an increase in pressure inside the cell: called turgor pressure (plants) or osmotic pressure (animals).
Increase in pressure in animal cells causes them to swell or even burst; gives plant cells shape and support.

27. Example Hypotonic Hypotonic: Water enters cell.
Cell swells and bursts (cytolysis).
Give plant cells shape and support.

29. Hypertonic Solution
Hypertonic solutions: the concentration of solute is higher outside the cell than inside the cell.
Have more water inside the cell so water moves out of the cell
Causes a drop in turgor or osmotic pressure: called plasmolysis.
Plasmolysis causes animal cells to shrivel up and plants to wilt.

30. Hypertonic Example Hypertonic: Water exits cell.
Cell shrinks (plasmolysis) due to    water loss.

32. The effects of osmotic pressure

33. Now, draw three beakers. Show a cell in hypertonic, isotonic, and hypotonic solutions.
Beaker A
Beaker B
Beaker C
Cell
Cell
Cell

34. Osmosis is the movement of water from ________ concentration to __________ concentration.

35. The water will move to the (left, right)

36. A shriveled cell is said to have a(n) __________ solution. A
A shriveled cell is said to have a(n) __________ solution. A. hypotonic B. isotonic C. hypertonic

37. A swollen cell has a hypotonic solution because the amount of water on the outside of the cell is (low, high)

38. The effects of osmotic pressure in a plant cell