1. 1. Cell Membrane phospholipid and protein “skin” around cytoplasm found in all cells SELECTIVELY PERMEABLE – some molecules easily cross the cell membrane (CM) others not at all protection communication fluid mosaic model – phospholipids and proteins move side to side 1

2. 1. Membrane Lipids phospholipid bilayer polar (hydrophilic) phosphate “head” two, nonpolar (hydrophobic) fatty acid tails heads point outward tails on interior of CM steroids animal cells – cholesterol plant cells – different steroid molecules 2

3. 1. Membrane Proteins peripheral (sides) proteins on interior and exterior of CM Integral (within) proteins some extend across CM form channels bind and carry molecules others do not hold adjoining cells together viruses, hormones attach to these proteins 3

4. 4 Phospholipids Integral protein Peripheral protein Fatty acid “tails” (lipids) Phosphate Group

5. 2. Passive Transport movement of molecules from HIGH concentration to LOW concentration NO ENERGY (ATP) input needed molecules MOVE DOWN the concentration gradient TYPES of passive transport simple diffusion facilitated diffusion osmosis 5 high low ANIMATION – passive transportpassive transport

6. 3. Examples of Simple Diffusion perfume sprayed in an enclosed space sugar cube (solute) dissolving in water (solvent) food coloring in water molecules in constant motion MOVE DOWN the concentration gradient when equilibrium reached – molecules still move, stay spread out 6 ANIMATION – simple diffusionsimple diffusion

7. 4. Diffusion Across Membranes molecules that CAN diffuse across the cell membrane high to low molecules that can dissolve in lipids can diffuse across the membrane carbon dioxide (CO 2 ), oxygen (O 2 ) – simple diffusion 7 ANIMATION – transport across the cell membranetransport across the cell membrane

8. 4. Diffusion Across Membranes molecules that CANNOT diffuse across the cell membrane ions (need ion channels) glucose (small, hydrophilic, need carrier proteins) macromolecules – proteins (exocytosis used), RNA water (VERY small, polar, needs aquaporin protein) 8 ANIMATION – transport across the cell membranetransport across the cell membrane

9. 5. Factors that Affect Diffusion steepness of concentration gradient (the difference in the concentration of molecules across a space) temperature charge diameter of the diffusing molecules 9

10. 6. Equilibrium the concentration of the molecules is the same across a space GOAL of diffusion is to reach equilibrium molecules still move, but there is no concentration gradient 10

11. 7. Osmosis the process by which water molecules diffuse across a cell membrane from high to low concentration NO ENERGY (ATP) input needed molecules MOVE DOWN the concentration gradient 11

12. 8. HypOtonic the concentration of solute molecules outside the cell is lower than the concentration inside the cell water diffuses INTO the cell until equilibrium is reached water molecules MOVE DOWN the concentration gradient 12 Draw and label your arrow to show the flow of water: hypO  hyper

13. 9. Hyp e rtonic the concentration of solute molecules outside the cell is higher than the concentration inside the cell water diffuses OUT OF the cell until equilibrium is reached water molecules MOVE DOWN the concentration gradient 13 Draw and label your arrow to show the flow of water: hypO  hyper

14. 10. Isotonic the concentration of solutes outside and inside the cell are equal water diffuses INTO and OUT OF the cell at the same rate no net movement of water 14

15. 11. How Cells Deal With Osmosis osmoregulation in freshwater fish keep body fluids from being too dilute or too concentrated having to pee after swimming in a pool contractile vacuoles organelles that remove water found in unicellular, freshwater organisms 15 Contractile vacuole video clip

16. 12. Turgor Pressure the pressure that water molecules exert against the cell wall in plant cells plants in a hypOtonic environment water diffuses INTO the plant cells and stored in the central vacuole 16

17. 13. Plasmolysis loss pressure between the CW and CM in a plant cell plants in a hypertonic environment water diffuses OUT of central vacuole CM pulls away from CW 17

18. 14. Cytolysis cell bursting animal cells in a hypOtonic environment water diffuses INTO the cell 18

19. 15. Crenation cell shrinking animal cells in a hypertonic environment water diffuses OUT OF the cell 19

20. 16. Facilitated Diffusion type of passive transport (no ATP, high to low) molecules move DOWN the concentration gradient some molecules can’t easily diffuse across the CM need a specific integral membrane protein (IMP) 20 high low

21. 16. Carrier Proteins – using glucose as an example carrier protein = specific IMP binds to glucose carrier protein changes shape glucose moves across the CM(high to low) carrier protein returns to original shape 21 ANIMATION – passive transportpassive transport

22. 16. Ion Channels ion channels = specific IMP ions are NOT soluble in lipids ion channel = passageway ions transported across the CM (high to low) some always open and some are gated 22

23. 16. Water aquaporin = specific IMP water is polar (hydrophilic) aquaporin = passageway water transported across the cell membrane (high to low) lots of aquaporin 23

24. 17. Active Transport movement of molecules from LOW concentration to HIGH concentration ENERGY (ATP) input needed molecules MOVE UP the concentration gradient TYPES of active transport membrane pumps endocytosis exocytosis 24 high low

25. 18. Sodium-Potassium Pump active transport (nerve cells) 3 sodium (Na+) ions bind to IMP pump(cytosol side) IMP changes shape (ATP used), 3 Na+ ions LEAVE the cell 2 potassium (K+) ions bind to same IMP pump (extracellular side) IMP shape change (ATP), 2 K+ ions ENTER the cell ions PUMPED from low to high, requires energy (ATP) 25 ANIMATION #1 – sodium-potassium pumpsodium-potassium pump ANIMATION #2 – sodium-potassium pumpsodium-potassium pump

26. 19. Endocytosis active transport cells ingest fluid, macromolecules, large particles part of the cell membrane used pouch formed around particle  vesicle lysosomes digest (break down) vesicle contents 26 ANIMATION – active transportactive transport

27. 19. Pinocytosis (type of endocytosis) type of endocytosis active transport transport of solutes or fluids 27

28. 19. Phagocytosis type of endocytosis active transport transport of large particles / whole cells phagocytes (white blood cells) ingest bacteria or viruses fuse w/ lysosomes  destroy bacteria or viruses 28 ANIMATION – phagocytephagocyte

29. 20. Exocytosis reverse of endocytosis vesicles in cytoplasm fuse w/ cell membrane contents of vesicles released from cell ex. release of proteins from the cell 29

30. Review Question #1 Draw the cell membrane. Which part of the cell membrane do/does… oxygen pass through? water pass through? carbon dioxide pass through? ions pass through? Explain what… selectively permeable means. fluid mosaic model means. 30

31. Review Question #2 Draw a picture of passive transport using a person, a bike, and a hill. Do molecules moves from high to low or low to high? Does the movement of molecules require energy? Please explain using the term concentration gradient in your explanation. Give two real examples of passive transport. Name two factors that can affect the rate of diffusion. 31

32. Review Question #3 Draw a cell membrane that shows that water is in equilibrium. Does water travel through the lipid bilayer or through a membrane protein when it crosses the cell membrane? If water is in equilibrium, do the molecules still move? Please explain. 32

33. Review Question #4 Draw a before and after picture of a plant cell that’s placed in a hypertonic environment. Does this plant cell experience a gain or loss of turgor pressure (plasmolysis)? Draw a before and after picture of a plant cell that’s placed in a hypotonic environment. Does this plant cell experience a gain or loss of turgor pressure (plasmolysis)? 33

34. Review Question #5 Draw a before and after picture of an animal cell that’s placed in a hypertonic environment. Does this animal cell experience cytolysis or crenation? Draw a before and after picture of an animal cell that’s placed in a hypotonic environment. Does this animal cell experience cytolysis or crenation? 34

35. Review Question #6 Draw a paramecium in a hypotonic (freshwater) environment. Draw an arrow to show how water moves. How does a paramecium deal with living in a hypotonic environment? 35

36. Review Question #7 Explain how facilitated diffusion is a type of passive transport. Use a diagram to help support your response. Draw and explain how carrier proteins work. Draw and explain how ion channels work. 36

37. Review Question #8 Define active transport. Draw and explain how the sodium-potassium pump works. Draw and explain how endocytosis works. Draw and explain how exocytosis works. 37