2. Regents Biology 2006-2007 Cell Membranes & Movement Across Them

3. Regents Biology Cell (plasma) membrane  Cells need an inside & an outside…  separate cell from its environment  ________________________________ IN __________ OUT __________ __________ __________ __________ __________ __________ __________ cell needs materials in & products or waste out

4. Regents Biology Building a membrane  How do you build a barrier that keeps the watery contents of the cell separate from the watery environment? What substance do you know that doesn’t mix with water?  _______  Remember: oil & water don’t mix!!

5. Regents Biology Lipids of cell membrane  Membrane is made of special kind of lipid  ______________________________  “split personality”  Membrane is a double layer  ______________________________ inside cell outside cell lipid “attracted to water” phosphate “attracted to water”

6. Regents Biology Semi-permeable membrane  Cell membrane controls what gets in or out  Need to allow some materials — but not all — to pass through the membrane  _____________________________________  _________________________________________ aa H2OH2O sugar lipidssalt waste So what needs to get across the membrane? O2O2

7. Regents Biology Crossing the cell membrane  What molecules can get through the cell membrane directly?  ____________________________________ inside cell outside cell lipid salt aa H2OH2O sugar waste but… what about other stuff?

8. Regents Biology Cell membrane channels  Need to make “doors” through membrane  ______________________________________________  _____________________________________________________  H 2 O channel, salt channel, sugar channel, etc. inside cell outside cell sugaraa H2OH2O salt waste

9. Regents Biology How do you build a semi-permeable cell membrane?  ___________________________________  proteins both “like” water & “like” lipids bi-lipid membrane protein channels in bi-lipid membrane

10. Regents Biology Protein channels  Proteins act as doors in the membrane  channels to move specific molecules through cell membrane HIGH LOW

11. Regents Biology Movement through the channel  Why do molecules move through membrane if you give them a channel? high low

12. Regents Biology Molecules move from high to low  ______________________________  move from ______ to _______ concentration

13. Regents Biology Diffusion  Move from ______ to ______ concentration  ______________________________ diffusion diffusion of water

14. Regents Biology Simple Diffusion  Move from _______ to _______ inside cell outside cell Which way will fat move? fat

15. Regents Biology Diffusion through a channel  Move from _______ to ________ inside cell outside cell sugar Which way will sugar move? sugar

16. Regents Biology Diffusion  Move from ______ to ______ concentration  directly through membrane  _____________________________  help through a protein channel  _____________________________ high low

17. Regents Biology Simple vs. facilitated diffusion inside cell outside cell lipid inside cell outside cell H2OH2O simple diffusionfacilitated diffusion H2OH2O protein channel

18. Regents Biology Active transport  Cells may need molecules to move _________ concentration “hill”  need to pump “uphill”  from ________ to ________ using ATP  _____________________________  __________ ATP

19. Regents Biology Transport summary facilitated diffusion active transport ATP facilitated diffusion

20. Regents Biology 2006-2007 Osmosis Movement of Water Across Cell Membrane

21. Regents Biology Osmosis  Water is very important, so we talk about water separately  _____________________  _____________________________________ _____________________________________  across a semi-permeable membrane

22. Regents Biology Keeping water balance  Cell survival depends on balancing water uptake & water loss ____________

23. Regents Biology Keeping right amount of water in cell  ______________________  a cell in _____________________  high concentration of water around cell  __________________________  example: ___________________  problem: ___________________ ___________________________  water continually enters Paramecium cell  solution: _____________________  pumps water out of cell freshwater

24. Regents Biology Controlling water  Contractile vacuole in Paramecium

25. Regents Biology Keeping right amount of water in cell  ___________________  a cell in ________________  low concentration of water around cell  _________________________  example: _______________  problem: _______________  _________________________  shrinking cell  solution: take up water saltwater

26. Regents Biology Keeping right amount of water in cell  ______________________  no difference in concentration of water between cell & environment  _____________________  example: _____________  problem: none  water flows across membrane equally, in both directions  volume of cell doesn’t change balanced