Homeostasis requires exchanging materials with the environment. How do you do it?

1. Homeostasis requires exchanging materials with the environment. How do you do it? Surfaces of contact with the environment let in oxygen and nutrients and excrete wastes.

2. The surface of contact between a cell and its environment is its plasma membrane.

3. Fluid Mosaic Model(description of membrane) Outside cell Inside cell

4. Cell/Plasma MembraneFluid Mosaic Model • The cell, or plasma membrane is made of hydrophobic molecules called phospholipids. • Proteins located in the membrane can flow/move and perform many functions, including receiving stimuli from the environment and transportingsubstances in and out of cell. ↓ The plasma membrane is semi-permeable / selectively permeable: it controls what goes in/out of cell

5. Cell Membrane Diagram(add details as you go) Phospholipidbilayer Outside cell Inside cell

6. PhospholipidBilayer Outside of Cell Hydrophilic Phosphate Heads HydrophobicTails Saturated or Unsaturated? Inside of Cell

7. Water moves freely through aquaporins. O2 and CO2 move freely through membrane. Polar particles need specialized carrier proteins:ions, glucose Media Links For Lecture\08-02-MembraneStructure.mov CellTransport  movement of substances in and out of cell, needed to maintain homeostasis What substances does a cell need to move in and out?

8. Passive Transport Does not require the use of energy from ATP. (uses the kinetic energy in matter/stuff moving in/out) Diffusion – Spreading of matter from one area to another. Matter always diffuses from areas of higher concentration to areas of lower concentration EQUILIBRIUM (same concentration everywhere) Diffusion is “free” because stuff moves down/with a concentration gradient. Ex.: food coloring spreading/mixing in water; H2O, O2, CO2, monomer nutrients (some) moving in/out of cell

9. Movie TimeCell Membrane & Passive Transport Mrs. Nordstrom: *press esc key (leave presentation mode), then double click below*

10. Osmosis – Diffusion of water through a semi-permeable membrane. Water flows from areas of lower solute concentration (+ water) to areas of higher solute concentration (- water). Osmosis - Solution Concentration & Effect on Cells (show cells in a solution & net movement of water) HypertonicIsotonic Hypotonic Very Hypotonic

11. Hypertonic Solution(Hypotonic Cell)Is there a concentration gradient? H2O Plasmolysis Cell shrinks (loses water)

12. Isotonic Solution(Isotonic Cell) Is there a concentration gradient? Equilibrium Happy cell 

13. Hypotonic Solution(Hypertonic Cell) Is there a concentration gradient? H2O Cell swells (gains water)

14. Very Hypotonic Solution H2O H2O H2O Cell swells (gains water) Cytolysis Cell lysis

15. Movie Time * • Osmosis OR The Movement of Water Through a Semi-Permeable Membrane Mrs. Nordstrom: *press esc key (leave presentation mode), then double click below*

16. Facilitated Diffusion – requires the use of a carrier protein on the cell membrane (still no ATP energy needed).Ex.: glucose molecules, ions – why? Polarity… Protein channels are specific for the particles they move. Carrier Protein / Ion Channel Glucose always use F.D. Ions use F.D.

17. Movie Time  Facilitated Diffusion Illustration At Colorado State Univ. Web Page

18. Hypotonic Hypertonic (Macroscopic Term) Turgid or Flaccid?? Salt Water

19. Hypotonic Hypertonic (Macroscopic Term) Turgid or Flaccid?? Tap Water

20. A B C

21. Prefix refers to the amount of Dissolved Solute (stuff) Hypertonic - Hypotonic - Isotonic – Excess ‘stuff’........ Less ‘stuff’………. Equal ‘stuff’…………

22. Osmosis Practice Can you predict what will happen? Think of water and solute concentrations. Water Pushes Out Cell’s Environment is 90% water Cell is 95% Water

23. Water Pushes into Cell Osmosis Cell’s Environment is 100% water Cell is 95% Water

24. EQUILIBRIUM Osmosis Cell’s Environment is 95% water Cell is 95% Water

25. Osmosis Cell’s Environment is 90% water Cell is 95% Water Hypotonic The Cell is ___________ Hypertonic The Cell’s environment is____________ The Future Fate of the Cell might be to PLASMOLYZE

26. Osmosis Cell’s Environment is 100% water Cell is 95% Water Hypertonic The Cell is ___________ Hypotonic The Cell’s environment is____________ The Fate of the Cell is Cytolysis

27. Osmosis Cell is 95% Water Cell’s Environment is 95% water The Cell’s environment is____________ ISOTONIC The Cell is ________________________ The Cell is at Equilibrium

28. Cyclosis

29. Plasmolysis

30. Which is more Plasmolyzed? Which might be further in the process of re-hydrating?

31. Hypotonic Env. Hypertonic Env. Hypotonic Cell Hypertonic Cell Normal Plant Cell Isotonic Cell Isotonic Environment Cytolysis Plasmolysis

32. RBC in Isotonic Environment The cell is also Isotonic Cytolysis Plasmolysis Cell is Hypotonic, Env. is Hypertonic Cell is Hypertonic, Env. Is Hypotonic

33. A B C

34. Simple Diffusion • Movement of ‘stuff’ down the Concentration Gradient through a semi-permeable cell membrane by Kinetic Energy Media Links For Lecture\08-10-Diffusion.mov

35. Osmosis • 2. Diffusion • 3. Facilitated Diffusion - Glucose • 4. Ion Channels Passive Transport Movement of water in / out of cell Movement of H2O, O2, CO2, Urea, monomer nutrients: either in / out of cell Movement of Glucose (C6H12O6) into the cell. Helped by a specific Integrated Protein Movement of ions in / out of cell, must go through specific integrated proteins