Diffusion and osmosis

1. Diffusion and osmosis

2. Weeee!!! high low This is gonna be hard work!! high low Types of Cellular Transport • Passive Transport cell doesn’t use energy • Diffusion • Facilitated Diffusion • Osmosis • Active Transport cell does use energy • Protein Pumps • Endocytosis • Exocytosis

3. Bacon Frying… What do you smell? Why do you smell this?

4. Bacon Frying… • Fat droplets are released into the air • steam coming off of the bacon • Causes the fat droplets (particles) to collide and disperse. • In science terms… • DIFFUSION IS OCCURING!  • The bacon fat droplets (particles) diffuse from the area of high concentration (directly above the frying pan), to areas of low concentration (the room) • Continues until equilibrium is reached • Particles equally distributed throughout the space (room)

5. Diffusion • Diffusion - Defined as the movement of particles from areas of high concentration to areas of low concentration (down the concentration gradient) • Particles spread out • Ex: Solute= perfume Solvent = the air Low Solute Concentration High Solute Concentration

6. Diffusion

7. Diffusion rate (how fast it occurs) depends on: • 1.Size-smaller molecules move more easily • 2.Concentration-high concentration = faster spread • Ex: The more bacon you have (=more fat droplets released), the faster the smell will spread throughout the room • 3. Temperature- high temps speed up the process • Which will cause the smell to disperse faster? • Cold bacon in a frying pan and the stove is OFF OR • Bacon in a frying pan and the stove in ON

8. What is a semi-permeable membrane? • A membrane that allows certain molecules to pass through it by diffusion or osmosis • Think about a Ping-Pong net.. • Which would pass through?

9. Osmosis • Diffusion that involves water. • Movement of water across a semi-permeable membrane

10. Cell membranes are semi-permeable • Water and some gases move through the membrane easily, while larger molecules like proteins and sugars do not. • Cells must regulate- molecules move from internal environment to external environment (and vice versa) so that both environments have equal concentrations. • Animation: How Osmosis Works

11. Osmosis • Diffusion that involves water. • Movement of water across a semi-permeable membrane • Water moves from areas of low solute to areas of high solute Why do your fingers “shrivel–up” when you are in the water?

13. Effects of Osmosis on Life • Osmosis- diffusion of water through a selectively permeable membrane. • There are 3 types of solutions (=Tonicity) 1.) Isotonic 2.) Hypertonic 3.) Hypotonic

14. WATCH VIDEO OF BLOOD IN AN ISOTONIC SOLUTION Isotonic Solution • Solutions that contain the same concentration of solutes as the cytoplasm are called isotonic (or normal saline) solutions. • There is no net movement of water either into or out of the cell. • Cells maintain their normal shape.

15. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution Isotonic The concentration of solutes in the external solution is equal to the concentration of solutes inside the cell. Result Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

16. WATCH VIDEO OF NORMAL RBCs SUBJECTED TO A HYPERTONIC SOLUTION Hypertonic Solution • A hypertonic solution is a solution that contains more solutes than the cytoplasm of the cell. (hyper) • Has less water than the cell and water moves out of the cell. • The cells shrink.

17. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis/crenation)!

18. WATCH VIDEO OF CRENATED RBCs SUBJECTED TO A HYPOTONIC SOLUTION Hypotonic Solution • A hypotonic solution contains less solute (thus, more water) than the cytoplasm of the cells. • The water will move into the cells resulting in the swelling and lysis of the cells. 

19. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

20. Let’s take a closer look! http://www.coolschool.ca/lor/BI12/unit4/U04L06/rbc.html

21. What type of solution are these cells in? B C A Hypertonic Isotonic Hypotonic

22. Tonicity • Used to compare different solutions • Hypertonic-higher solute concentration relative to another *think hyperactive • Hypotonic- lower solute concentration relative to another *think hypothermia • Isotonic- equal solute concentrations between two solutions

23. Cell in Isotonic Solution ENVIRONMENT 10% NaCL90% H2O CELL NO NET MOVEMENT 10% NaCL 90% H2O equilibrium The cell is at _______________. What is the direction of water movement?

24. Cell in Hypotonic Solution 10% NaCL90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement??

25. Cell in Hypertonic Solution 15% NaCL85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement?

26. Cells in Solutions

27. Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS

28. Cytolysis & Plasmolysis Plasmolysis Cytolysis

29. Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic

30. What Happens to Blood Cells?