1. CH. 3 ~ CELLS

2. Cell Membrane 1.Surrounds ALL cells 2.Has a “Phospholipid bilayer” which makes it “flexible and “fluid”

3. Cell Membrane “Phospholipid bilayer” - Phosphate ‘head’ (polar- hydrophillic) -2 Lipid ‘tails’ (nonpolar- hydrophobic) -What is “Polar” vs “Nonpolar”?

4. Water Molecule 2 Hydrogen Atoms + 1 Oxygen Atom A water molecule is a ‘polar’ molecule because it has a partial negative charge on one side and a partial positive charge on the other side. When the Hydrogen atom of one water molecule is attracted to the oxygen atoms of another water molecule a hydrogen bond is formed. Lipids are Nonpolar molecules

5. Cell Membrane 3.Semi-permeable – only allows certain substances to pass through 4.Contains proteins- some used for identification and some for transport (that help to pass materials through).

6. Transport of materials into and out of the cell Passive Transport – movement of molecules that does not require energy. –Usually from high concentration to lower concentration ex. Diffusion, Osmosis, Facilitated diffusion Active Transport – movement of molecules that requires energy. –Usually from low concentration to high concentration (against the concentration gradient) ex. Pumps, endocytosis, exocytosis

7. Passive Active Diffusion Osmosis Facilitated Diffusion Pumps Endocytosis Exocytosis

8. Terms: Equilibrium – when 2 given areas have the same concentration of molecules. Concentration Gradient – the difference in concentration of molecules in 2 given areas. (Ocean- swimming with the tide or against it- which requires energy?) Defines HOW molecules will move, if going WITH the concentration gradient (from high to low = passive transport) or AGAINST it (from low to high = requires energy = active transport

9. Passive Transport: 1. Diffusion – movement of molecules from an area of high concentration to an area of lower concentration.

10. Passive Transport: 2. Osmosis – diffusion of water 3. Facilitated diffusion – passive transport of materials across a cell membrane using protein channels.

11. Facilitated Diffusion (complete on back of the notes) Protein Channels Carrier Proteins

12. Facilitated Diffusion Increases the rate of diffusion Similar to simple diffusion in the sense that it is diffusion (across a membrane) from a high concentration to a lower concentration. However, this time the rate of diffusion is greatly accelerated by the action of membrane proteins that act as carrier molecules and aid in diffusion. http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

13. Passive vs. Active Transport Passive Transport - Transport processes that happen "passively" without the cell needing to expend any energy to make them happen. Active Transport - transport processes that require energy from the cell's reserves to "power" them.

14. Pictures of Passive and Active Transport (complete on back of the notes) Using a Protein Pump Using a Protein Channel Energy Added

15. Pumps Type of active transport Move molecules from an area of LOW concentration to an area of HIGH concentration

16. ACTIVE Na-K (sodium-potassium) Pump

17. ACTIVE Endocytosis Intake of material (food) using the cell membrane Cell membrane surrounds material and encloses it – forming a vesicle/vacuole.

18. Amoeba Eating

19. ACTIVE Exocytosis Removal of material (waste) from a cell. Golgi Apparatus “packages” the material into a vesicle and sends it to the cell membrane The vesicle fuses with the membrane The material is deposited outside the cell

20. Exocytosis

21. Endocytosis and Exocytosis (complete on back of the notes) http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

22. PASSIVE ACTIVE NO ENERGY Diffusion of perfume, food coloring Osmosis Facilitated diffusion –Protein channels –Carrier proteins ENERGY Exocytosis –GA packages and secretes wastes Endocytosis –Membrane surrounds and engulfs food, etc. (Amoeba) Pumps –Sodium-Potassium

23. Electron Micrograph of Exocytosis This figure was taken from Alberts et al, Molecular Biology of the Cell, Garland Publishing Third Edition, 1994

24. DIALYSIS DEMO The small molecules of water and iodine moved from an area of high concentration, outside the cell, to an area of low concentration inside the cell in order to try to reach equilibrium. The large molecules of starch were not able to diffuse and reach equilibrium because they were too large to pass through the semi-permeable membrane.

25. Solute vs. Solvent Osmosis and Tonicity Solution – a homogenous (same throughout) mixture Solvent – the substance in a solution that dissolves other substances (solutes) Solute – the substance in a solution that is dissolved.

26. Another way to think about it: a solute is dissolved in another substance, known as a solvent. Usually, the substance present in a greater amount is considered as the solvent.solutesolvent Which is the solute? Solvent? Explain your rationale water and kool-aid. WATER IS THE UNIVERSAL SOLVENT

27. Osmosis A type of diffusion The movement of WATER from an area of ______ concentration to an area of ____ concentration

28. There are 3 types of osmotic solutions Hypotonic – there is a greater concentration of solute (ie, salt, the ‘stuff’) in the cell then in the fluid around the cell Hypertonic – there is a greater concentration of solute (ie, salt, the ‘stuff’) in the solution than in the cell Isotonic - equilibrium

29. Another way to think about it Hypotonic – more water outside the cell, therefore water rushes into the cell Hypertonic – more water inside the cell, therefore water rushes out of the cell Isotonic – same amount of water inside and outside the cell so nothing changes

31. Whenever solutes (dissolves substances) are added to water, they decrease the number of free water molecules; more solute molecules, fewer free water molecules

32. Osmosis in Red Blood Cells

33. Hypo Iso Hyper

34. Osmosis in a Plant Cell Hypo Iso Hyper

35. Osmosis in a Plant Cell

36. Comparison of Plant and Animal Cells in Osmotic Solutions What is the major differences between what happens in plant and animal cells when placed in a hypotonic solution?

40. PASSIVE ACTIVE Material only moves DOWN the concentration gradient (from HIGH to LOW concentration). Material can move up OR down the concentration gradient since energy is used to move the material.

41. http://www.nclark.net/BioChapter8

42. Animation www.biologycorner.com/bio1/diffusion.html http://www.nclark.net/BioChapter8