2. AP Biology 2007-2008 Movement across the Cell Membrane

3. AP Biology Diffusion  ______________________________ governs biological systems  universe tends towards disorder (entropy)  Diffusion  movement from ___________concentration  Diffusion  movement from ___________concentration

4. AP Biology Diffusion  Move from ______to _____concentration  “passive transport”  no energy needed diffusionosmosis movement of water

5. AP Biology Diffusion across cell membrane  Cell membrane is the boundary between inside & outside…  separates cell from its environment IN _________ carbohydrates sugars, proteins amino acids lipids salts, O 2, H 2 O OUT ________ ammonia salts CO 2 H2OH2O products ______________________________________________ IN OUT Can it be an impenetrable boundary? NO!

6. AP Biology Diffusion through phospholipid bilayer  What molecules can get through directly?  fats & other lipids  Small polar molecules (H 2 0) inside cell outside cell lipid salt aa H2OH2O sugar NH 3  What molecules can ________get through directly?  ions  salts, ammonia  large molecules  starches, proteins

7. AP Biology Channels through cell membrane  Membrane becomes ________________ with protein channels  specific channels allow specific material across cell membrane inside cell outside cell sugaraa H2OH2O salt NH 3

8. AP Biology Facilitated Diffusion  Diffusion through protein channels  channels move specific molecules across cell membrane  no energy needed open channel = fast transport facilitated = with help _____ ______

9. AP Biology Active Transport  Cells may need to move molecules ___________ concentration gradient  shape change transports solute from one side of membrane to other  _________________  “costs” energy = _____ low high

10. AP Biology Getting through cell membrane  ____________________  _______________________  diffusion of nonpolar, hydrophobic molecules  lipids  high  low concentration gradient  _____________________  diffusion of polar, hydrophilic molecules  through a ____________________  high  low concentration gradient  _______________________  diffusion __________________________  low  high  uses a _________________  requires _____ ATP

11. AP Biology Transport summary simple diffusion facilitated diffusion active transport ATP

12. AP Biology How about large molecules?  Moving large molecules into & out of cell  through vesicles & vacuoles  ______________  _____________________ = “cellular eating”  _____________________ = “cellular drinking”  ________________ exocytosis

13. AP Biology Endocytosis _________________ ________________ fuse with lysosome for digestion non-specific process triggered by molecular signal

14. AP Biology Phagocytosis

15. AP Biology Osmosis is diffusion of water  Water is very important to life, so we talk about water separately  Diffusion of water from __________________of water to __________________of water  across a semi-permeable membrane

16. AP Biology Concentration of water  Direction of osmosis is determined by comparing total solute concentrations  ___________ - more solute, less water  ___________ - less solute, more water  ___________ - equal solute, equal water hypotonichypertonic water _____ movement of water

17. AP Biology ___________ __________ Managing water balance  Cell survival depends on balancing water uptake & loss

18. AP Biology Managing water balance  Isotonic  animal cell immersed in ___________solution  example: ________________________  problem: none  _________________of water flows across membrane equally, in both directions  volume of cell is stable balanced

19. AP Biology Managing water balance  Hypotonic  a cell in ____________  example: __________________  problem: __________________ swells & can burst  water continually enters Paramecium cell  solution: __________________  pumps water out of cell  ATP  plant cells  turgid freshwater ATP

20. AP Biology Water regulation  Contractile vacuole in Paramecium ATP

21. AP Biology Managing water balance  Hypertonic  a cell in ________________  example: ________________  problem: _________________  solution: take up water or pump out salt  plant cells  ________________ = wilt saltwater

22. AP Biology Cell (compared to beaker)  hypertonic or hypotonic Beaker (compared to cell)  hypertonic or hypotonic Which way does the water flow?  in or out of cell.05 M.03 M Osmosis…

23. AP Biology Any Questions??